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Anticipation of Pain: Psychophysiological Reactions and the Role of Dental Fear

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Title:
Anticipation of Pain: Psychophysiological Reactions and the Role of Dental Fear
Creator:
SILAKOWSKI, TAMMY D. ( Author, Primary )
Copyright Date:
2008

Subjects

Subjects / Keywords:
Anticipation ( jstor )
Anxiety ( jstor )
Fear ( jstor )
Galvanic skin response ( jstor )
Heart rate ( jstor )
Pain ( jstor )
Physiological stimulation ( jstor )
Questionnaires ( jstor )
Reactivity ( jstor )
Startle reflex ( jstor )

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University of Florida
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University of Florida
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Copyright Tammy D. Silakowski. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Embargo Date:
5/31/2010
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670352240 ( OCLC )

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ANTICIPATION OF PAIN: PSYCHOPHYSIOLOGICAL REACTIONS AND THE ROLE OF DENTAL FEAR By TAMMY D. SILAKOWSKI A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2005

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Copyright 2005 by Tammy D. Silakowski

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iii ACKNOWLEDGEMENTS This research was supported in part by National Institutes of Health grant DE13956 awarded to Margaret M. Bradley. The author wishes to thank Dr. Margaret Bradley for her support and guidance throughout the research process, and Dr. Peter Lang and Dr. Keith Berg for their helpful comments. The author is also grateful for Laura Miccoli’s assistance with data collection.

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iv TABLE OF CONTENTS page ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii CHAPTER 1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Threat of Shock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Emotion and Psychophysiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Dental fear and Psychophysiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2 METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Participants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Materials and Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Questionnaires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Physiological Response Measurement and Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Startle Reflex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Skin Conductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Corrugator EMG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Heart Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Questionnaires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Physiological Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Startle Reflex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Skin Conductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Corrugator EMG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Heart Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Shock Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

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v 4 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 APPENDIX A DEFAULT.VPM FILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 B PHYSIO1.VPM FILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 C PIC1.VPM FILE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 D DENTAL FEAR SURVEY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 E FEAR OF DENTAL PAIN QUESTIONNAIRE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 F STATE-TRAIT ANXIETY INVENTORY (STAI-T) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 G MUTILATION QUESTIONNAIRE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 H POSTEXPERIMENTAL QUESTIONNAIRE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 LIST OF REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 BIOGRAPHICAL SKETCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

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vi TABLE Table page 3-1. Mean values of physiological activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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vii LIST OF FIGURES Figure page 1-1. Brain structures involved in mediating defense system responses . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2-1. Distribution of dental fear pre-screening scores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2-2. Schematic of trial design and timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3-1. Startle magnitude during threat of shock and safe periods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3-2. Startle magnitude across the experiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3-3. Startle magnitude by threat of shock condition and picture viewing context . . . . . . . . . 26 3-4. Skin conductance during threat of shock and safe periods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3-5. Skin conductance by threat of shock condition and dental fear group . . . . . . . . . . . . . . . . . . . 28 3-6. Skin conductance responses across the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3-7. Skin conductance by threat of shock condition, dental fear group, and pre-/ postshock period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3-8. Corrugator EMG by threat of shock condition and picture viewing context . . . . . . . . . . 31 3-9. Corrugator EMG by threat of shock condition and picture valence. . . . . . . . . . . . . . . . . . . . . . . 31 3-10. Heart rate by threat of shock condition and picture viewing context . . . . . . . . . . . . . . . . . . . . . 32 3-11. Mean heart rate change (bpm) by dental fear group (top panel), and by dental fear group as a function of picture viewing context (bottom panel). . . . . . . . . . . . . . . . . . . . . . . 33

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viii Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Master of Science ANTICIPATION OF PAIN: PSYCHOPHYSIOLOGICAL REACTIONS AND THE ROLE OF DENTAL FEAR By Tammy D. Silakowski May 2005 Chair: Margaret M. Bradley Major Department: Psychology Dental fear affects a large portion of the population (16-20%), and survey research suggests that fear of pain is a key component of dental fear. Using the threat of shock paradigm, we examined physiological reactivity while high and low dental fear individuals anticipated a painful stimulus (electric shock) and also during periods of safety from shock. We reasoned that if high dental fear individuals are indeed more fearful of pain, they should exhibit enhanced physiological reactivity during pain anticipation compared to the low dental fear individuals. In order to examine emotional modulation during threat of shock and safe periods, participants also viewed affective pictures. Overall, startle magnitude was larger under the threat of shock compared to safe periods, which replicates prior research. This was accompanied by increased skin conductance and corrugator muscle activity (EMG), which suggests that shock threat was aversive and arousing. The startle reflex and corrugator EMG were modulated by picture

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ix valence both during shock threat and safe periods in a manner consistent with prior research, with potentiated startle and increased corrugator EMG during unpleasant compared to pleasant pictures. Compared to low dental fear individuals, the high dental fear group exhibited a greater skin conductance increase during shock threat, suggesting they were more physiologically aroused. High, but not low, dental fear individuals also continued to exhibit increased skin conductance during shock anticipation throughout the experiment. These results elucidate physiological changes that occur when participants are anticipating a painful stimulus, and are consistent with the hypothesis that dental fear is related to fear of painful stimuli.

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1 CHAPTER 1 INTRODUCTION Imagine yourself reclined in a dentist’s chair, blinded by the overhead light and overwhelmed by the smell of latex and other medical odors. You see the dentist lean over you, hear the whizzing of the drill, and finally feel it vibrate and pound against your jaw as the dentist drills into your tooth. Although this scenario is unpleasant for everyone, a portion of the population reports significant fear of dental treatment that interferes with dental health. In a recent population-based study, 16% of those sampled reported being anxious about dental visits (Locker et al., 1999). In a similar study, Milgrom and colleagues (1988) reported that 50% of participants reported some amount of dental anxiety, and classified 20.4% of those surveyed as high in dental fear (individuals “somewhat afraid,” “very afraid,” or “terrified” of dental treatment). This fear translates into considerable anxiety during dental treatment: in one survey of dentists, 75% agreed that dental anxiety was the largest obstacle to providing adequate patient care (Corah et al., 1985). Dental fear is also associated with avoidance of dental appointments, which may lead eventually to an increased risk for conditions requiring treatment and treatment complications. For example, Milgrom and colleagues (1988) noted that 31% of high dental fear individuals reported that they had cancelled or missed dental appointments more than once or twice (compared to 9% in the low dental fear group). Moreover, 24% of the high dental fear group had not been to a dentist in over two years, while this was true for only 10% of their low dental fear counterparts.

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2 A large body of literature suggests that fear of pain is a key component of dental fear. Using a factor analytic approach, McNeil and Berryman (1989) concluded that fear of pain was a better predictor of dental fear than fears of claustrophobia, social contact, and mutilation (e.g., the sight of blood or injury). Fear of pain is also a better predictor of dental fear than a number of factors related to pain experience and control, including the number of painful dental experiences, ability to accept pain, perceived control, and the desire for control (Liddell & Locker, 1997). A more recent study found that fear of pain predicted dental fear, while symptoms of depression and anxiety did not, both in orofacial pain patients and ageand gender-matched controls (McNeil et al., 2001). Research has also examined the relationship between dental fear and actual experienced pain. Lautch (1971) assessed pain threshold levels in dental phobics and controls (matched for age and gender) seeking emergency treatment at a dental hospital. In this severely distressed group of dental phobics (all insisted on needing general anesthesia in order to endure dental treatment), pain threshold levels to tooth shock were significantly lower than low dental fear controls. Similarly, avoidant dental phobics who responded to advertisements for behavioral treatment for their dental avoidance had lower pain tolerance for tooth shock (but not arm shock) than participants who were recruited for being “fearless” with respect to dental treatment (Klepac et al., 1982). However, a different pattern emerges when individuals high in dental fear (but not clinically phobic) are studied. Using a paradigm similar to their earlier study, Klepac and colleagues (1980) selected college students with high and low levels of dental fear, and participants received a series of electric shocks on the arm and on a tooth. The high and low dental fear groups did not differ in threshold level, tolerance level, or pain ratings for

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3 arm shock. Similarly, the two groups did not differ in actual threshold or tolerance for tooth shock. However, high dental fear participants rated tooth shock to be more painful than the low dental fear participants. That is, both groups had the same pain tolerance for tooth shock, yet the high dental fear group rated this shock as more painful. Arntz and colleagues (1990) examined the roles of predicted, experienced, and remembered pain in an actual dental setting. Dental patients in the study completed dental treatments that were known to possibly involve pain (e.g., root canals, dental fillings, etc.) at two appointments on separate days. Individuals who reported higher levels of dental fear overpredicted the pain they would experience just prior to treatment at both sessions. Immediately following treatment, these individuals also predicted a higher level of pain in future dental treatments than low dental fear individuals. However, the high and low dental fear individuals did not differ in their ratings of actual pain experienced during treatment. Importantly, at a five-month follow-up, low dental fear individuals accurately recalled their experienced pain, while high dental fear individuals recalled more pain than was actually experienced during treatment. Thus experienced pain does not appear to differ by dental fear level in a non-clinical sample, but fear of pain and the expectation of pain appear to play an important role in the perception of dental treatment. In addition, anxiety associated with the anticipation of pain has been shown to decrease pain thresholds (Rhudy & Meagher, 2000). Individuals anticipating painful electric shock (but never receiving shock) had decreased pain thresholds after shock anticipation as assessed with finger withdrawal latency on a radiant heat pain test. However, pain thresholds increased for individuals exposed to a series of shocks, and

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4 remained stable for individuals in a no-shock control condition. It is possible that anxiety-induced hyperalgesia may also contribute to the etiology of dental fear. These studies highlight the critical role of emotional experience in dental fear. A better understanding of this affective component may lead to a better understanding of individual differences in dental fear and improved treatment options. The current study assessed the hypothesis that if individuals who report high levels of dental fear are indeed more fearful of pain, they should exhibit greater physiological reactivity during anticipation of a painful stimulus as compared to individuals low in dental fear. Threat of Shock In order to assess physiological reactivity during anticipation of pain, the current study employed the threat of shock paradigm, in which participants are signaled that electric shock is or is not possible at various times (Grillon et al., 1991). This paradigm has its roots in animal conditioning studies. In the classic study in this area, Brown, Kalish, and Farber (1951) used a fear conditioning paradigm to examine startle responses in rats. Shocks were paired with presentation of a light for the experimental group, while the shocks and light were not paired in the control group. Compared to control rats, the experimental group had a significantly larger startle reflex (elicited by a loud noise) in the presence of the conditioned stimulus (light) that had previously been paired with shock. This “fear-potentiated startle” phenomenon has been replicated in a number of human and animal conditioning studies (e.g., Davis, 1989; Hamm et al., 1993; Spence & Runquist, 1958). A modified version of shock conditioning procedures, the threat of shock paradigm, relies on verbal instruction rather than conditioning to induce fear. Participants are

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5 instructed that they can receive an electric shock whenever a particular stimulus such as a light is present (“threat” condition) but never when a second stimulus is present (no shock or “safe” condition). Grillon and colleagues (1991) instructed participants that the shocks would be painful sensations. Startle responses during the shock anticipation periods were larger than during safe periods. Startle magnitude did not decrease or habituate across the experiment, which is likely due to the fact that participants were instructed that shock intensities would increase over time. The persistence of fear-potentiated startle throughout the hour-long experiment is noteworthy, since only one shock was delivered midway through the experiment. The startle reflex was also elicited more rapidly during threat of shock compared to safe periods. Using state anxiety as a measure of shock fear, Grillon and colleagues (1993a) also found that high fear subjects exhibited a larger startle magnitude during threat of shock than low fear participants, although the two groups did not differ in startle magnitude during the safe condition. Kopacz and Smith (1971) found that skin conductance responses to a brief 90 dB tone were greater during shock anticipation compared to a rest period prior to shock electrode placement. In addition, basal levels of skin conductance and skin conductance responses to tones were greatest for participants expecting a high probability of shock, intermediate for moderate threat probability, and lowest for participants instructed that they would not receive shocks. Heart rate is also modulated by shock threat. During the first shock threat trial, Deane (1961) found that heart rate accelerated just prior to and during the time that shock was expected. However, on subsequent trials participants actually showed marked deceleration during this same time period.

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6 Emotion and Psychophysiology Emotion can be conceptualized in terms of two motivational states, appetitive and defensive, which have implications for the survival of an organism (Lang et al., 1990). The appetitive system mediates approach and consummatory behavior, while the defensive system is related to defense behavior, escape, and avoidance. For example, the defensive system is engaged when a person runs away from a snake, with sweaty palms and a pounding heart. Lang’s motivational priming hypothesis (Lang et al., 1990) suggests that emotional engagement activates subcortical brain structures that in turn prime physiological responses associated with the appetitive or defensive systems. Responses associated with the defensive system (such as the startle reflex in response to a sudden loud noise) should be primed and hence potentiated during an ongoing negative emotion or aversive context. Indeed, when people are shown pictures rated as unpleasant (such as pointed guns or attacking dogs), startle probes elicit a larger startle reflex as compared to pictures rated neutral or pleasant (Lang et al., 1990). The brain circuits underlying defense system activation and mediating output have been well characterized based on fear conditioning studies with rats (see Figure 1-1). In the presence of a threatening stimulus, sensory information proceeds from sensory cortex through the thalamus to the lateral nucleus of the amygdala (Le Doux, 1990). From the lateral amygdala, signals proceed to the central nucleus of the amygdala, which projects to several subcortical structures that modulate output systems. The lateral hypothalamus modulates autonomic nervous system activity (Le Doux, 1990). The periaqueductal gray (PAG) is important in mediating motor output. The ventral PAG is involved in freezing behavior-lesions to this region cause a pronounced decrease in freezing (Fanselow et al.,

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7 1995). The dorsolateral PAG appears to mediate circa-strike or active defense behaviors via an inhibitory influence on the ventral PAG. When the dorsolateral PAG is lesioned, freezing behavior is enhanced. The amygdala also projects directly to the nucleus reticularis pontis caudalis in the startle pathway, which provides the basis of fear conditioning modulation of the startle reflex (Boulis & Davis, 1989; Davis et al., 1993). Figure 1-1. Brain structures involved in mediating defense system responses. Figure adapted from Lang, Bradley, and Cuthbert (1997). Electrical stimulation of the amygdala potentiates startle, while amygdalar lesions block both acquisition and expression of fear-potentiated startle (see Davis et al., 1993, for a review). Additionally, administration of drugs such as diazepam that humans report as anxioloytic reduce fear-potentiated startle in rats (Berg & Davis, 1984).

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8 A great deal of research exists concerning the relationship between emotion and physiological reactivity in humans (e.g., Bradley, 2000; Bradley et al., 2001a; Lang et al., 1990; Lang et al., 1993). A common method for eliciting emotion in the laboratory is presenting emotional pictures. For example, the International Affective Picture System (IAPS; CSEA NIMH, 2001) contains nearly a thousand images that have been rated for emotional valence (how pleasant, neutral, or unpleasant the image is) and arousal (how intense the image is). In addition to the startle reflex, facial muscle activity varies by emotional valence: corrugator (frown) muscle activity is greatest during presentation of unpleasant pictures, while zygomatic (smile) muscle activity is greatest during pleasant pictures (Bradley et al., 2001a). Motivational differences are also evident in the heart: heart rate slows during picture presentation (indicative of orienting; Graham & Clifton, 1966), but deceleration is greatest during unpleasant pictures (know as “fear bradycardia”). Skin conductance, however, varies with rated emotional arousal: sweat gland activity increases with more intense stimuli, regardless of whether they are pleasant or unpleasant. Picture perception paradigms have also been employed in studying phobics’ reactions to their specific feared object. Exposure to such stimuli is expected to prompt fear and potentiate the startle reflex and other physiological responses. For example, one study compared startle and autonomic reactivity in animal phobics (snakes or spiders) and non-phobic participants (Hamm et al., 1997). For non-phobic slides, the two groups showed similar levels of startle reactivity, with greater startle magnitude during unpleasant compared to pleasant pictures. Both groups also showed greater skin conductance during affective compared to neutral pictures, and heart rate deceleration

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9 during picture viewing. When shown pictures of snakes and spiders, the non-phobic group showed a pattern of physiological reactivity similar to that seen with other unpleasant picture contents. However, compared to unpleasant pictures, the phobic group showed a significant enhancement of the startle reflex and skin conductance while viewing pictures of their feared object (i.e., snakes or spiders). The phobic group also exhibited significant heart rate acceleration when shown their feared object, which is in contrast to the deceleration seen when viewing other unpleasant contents. This heart rate acceleration is interpreted as a defense response to the phobic object and an activation of the sympathetic system, which prepares the body for fight-or-flight action (Graham & Clifton, 1966; Lang, Bradley, & Cuthbert, 1997). Dental fear and Psychophysiology Research has also examined dental phobics’ physiological reactivity during anticipation of or exposure to dental stimuli. Caprara and colleagues (2003) measured dental patients’ skin conductance level in order to determine if skin conductance might serve as an objective measure of dental fear. While resting in a dental chair several minutes prior to treatment, high dental fear individuals had a greater mean skin conductance level than low dental fear individuals. Skin conductance level was also correlated with patients’ rated fear of injection in the mouth. In another study, dental phobics were exposed to videos of dental procedures while seated in a dental examination chair (Johnsen et al., 2003). Compared to baseline measures acquired in an interview room, participants exhibited a significant increase in skin conductance and heart rate during exposure, as well as a decrease in heart rate variability. However, this study failed to include a non-phobic control group, so one

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10 cannot conclude that this pattern of physiological reactivity in this situation is unique to dental phobics. Lundgren and colleagues (2004) exposed dental phobics seeking treatment for their phobia to a series of short film clips depicting neutral scenes and dental scenes (drilling, injection, and a masked dentist explaining that extensive treatment is necessary). Compared to the neutral films, dental phobics showed increased skin conductance, heart rate, and forehead muscle tension during the dental films. Using the same paradigm, a low dental fear control group was included in another study (Lundgren et al., 2001). Dental phobics exhibited greater heart rate acceleration than controls only during the drilling film, and greater muscle tension during both the injection and drilling films. However, dental phobics and controls did not differ in skin conductance response. One study measured heart rate and blood pressure during a moderately painful automated procedure to measure gum attachment (Sullivan et al., 1996). Patients responded similarly during these procedures regardless of their level of dental fear, and differed only during a recovery period: blood pressure decreased for the low dental fear individuals, while it continued to rise or remain stable for individuals with a medium to high level of dental fear. Thus, dental phobics’ enhanced skin conductance prior to treatment and heart rate acceleration during dental films is consistent with the Hamm et al. (1997) study with animal phobics and notion of a “defense response.” As indicated earlier, prior research suggests that, in addition to dental stimuli, dental phobics are also more fearful of pain than individuals with low levels of dental fear. The current study employs the threat of shock paradigm to examine pain anticipation in both high and low dental fear individuals.

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11 The hypothesis is that if high dental fear individuals are indeed more fearful of pain in general, they should exhibit greater physiological reactivity during anticipation of electric shock compared to low dental fear individuals. Physiological measures included startle, skin conductance, corrugator muscle activity, and heart rate. Affective pictures were also presented during some threat and safe periods in order to assess emotional modulation during these periods.

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12 CHAPTER 2 METHOD Participants Females were recruited for initial testing since past research indicates females tend to show greater pain sensitivity (Riley et al., 1998) and are more physiologically reactive to unpleasant stimuli (Bradley et al., 2001b). Individuals were identified as potentially high in dental fear based on three items assessing dental anxiety and avoidance, which were administered as part of a larger pre-screening questionnaire to all Introductory Psychology students. Figure 2-1 shows the distribution of dental fear pre-screening scores for the entire sample of females who completed the survey (n=560). Figure 2-1. Distribution of dental fear pre-screening scores for female respondents (n=560). Individuals who were identified as potentially high in dental fear (n=31) are shown to the right of the dashed line. 0 1 2 3 4 5 6 7 8 9 10 11 12 0 20 40 60 80 100 Score Number of Respondents Individuals selected for high dental fear

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13 Females with a total score of 9 or greater on the sum of these three pre-screening items (possible range 0-12) were identified as potentially high in dental fear (n=31). The experimenter attempted to contact these individuals regarding study participation. Other females (assumed to be low in dental fear given their prevalence in the sample) were not selected in advance, but were allowed to sign-up for study participation through the Psychology Department’s experiment website. In all, 41 females were recruited from Introductory Psychology courses at the University of Florida, and they received class credit or were paid $25 for participation. Three individuals (two identified as potentially high in dental fear) declined to participate after reading the informed consent form, resulting in a sample of 38 participants (mean age 18.8, range 18-22). Preliminary identification of these 19 high and 19 low dental fear individuals based on pre-screening items matched well with scores on the more complete Dental Fear Survey (Kleinknecht et al., 1973; see Appendix D), which was administered at the end of the experiment. For analysis purposes, individuals were classified as “high dental fear” based on a score of 60 or greater (range: 20-100) on the 20-item Dental Fear Survey (Milgrom et al., 1992). Three of the 19 individuals identified as potentially high in dental fear at pre-screening were reclassified into the low dental fear group based on the more complete Dental Fear Survey. This classification resulted in 16 high and 22 low dental fear participants. Due to equipment failure or experimenter error, data were excluded for one participant for skin conductance (final n=37, 16 high dental fear) and heart rate (final n=37, 15 high dental fear).

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14 Materials and Design Participants were instructed that a red light (or blue light-the color was counterbalanced across participants) cued that shock was possible whenever it was illuminated (“threat” condition), while no shock was possible when the blue (or red) light was present (“safe” condition). Red and blue color slides were projected onto the wall across from the participant (an area approximately 32 inches wide by 18 inches high) using a Kodak Ektapro 9010 slide projector. Cue lights were illuminated for 20 seconds (s), with a 2 s inter-trial interval (ITI) in which no cue light was present. Figure 2-2 (left panel) illustrates the features and timing of safe and threat trials. Figure 2-2. Schematic of trial design and timing for cue light only trials (left panel) and picture viewing trials (right panel). During half of the trials participants viewed affective pictures in addition to the cue light. Pictures were selected from the International Affective Picture System (IAPS; Pictures + Cue light Cue light only Safe 2s ITI 20s Threat 2s ITI Safe 4s 2s 2s 4s 4s 2s ITI 2s 2s Threat 2s ITI startle probe 4.5s 10.5s 16.5s

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15 CSEA NIMH, 2001) based on normative valence and arousal ratings. Participants viewed 102 pictures, one-third from each valence category: pleasant, neutral, and unpleasant 1 . Pleasant and unpleasant pictures were matched for rated arousal. Pleasant pictures depicted erotica, adventure scenes, food, and other objects. Neutral pictures showed human faces and objects such as books and household items. Unpleasant pictures depicted scenes of threat (e.g., pointed guns), mutilated bodies, disaster scenes (e.g., crashed airplane), and contaminated items (e.g., roach crawling on pizza). For each picture viewing trial, one picture from each of the three valence categories was presented for 4 s, separated by a 2 s inter-picture interval (see Figure 2-2, right panel). The cue light was on continuously throughout the picture viewing trials. Picture valence was counterbalanced across picture position both within and between subjects such that pictures of each valence were presented approximately equally in each of the three picture positions for each participant. Picture presentation was controlled by VPM software (Cook, 2001) on a PC computer, and pictures were presented on a 19-inch View Sonic 21PS color monitor that was placed at eye-level approximately 50 inches from the participant. Participants were instructed to focus on a fixation point at the center of the monitor throughout the study; the cue lights were projected onto a wall area just above and beyond the monitor, and were easily discerned in participants’ peripheral vision. 1 IAPS numbers for pictures used: Pleasant: 4659, 4659, 4660, 4664, 4670, 4681, 4690, 4800, 4810, 5260, 5621, 5849, 5910, 7230, 7260, 7270, 7289, 7330, 7350, 7450, 7460, 8030, 8162, 8170, 8178, 8179, 8185, 8186, 8370, 8490, 8500, 8501, 8502, 8531; Neutral: 2190, 2191, 2200, 2210, 2214, 2383, 2393, 2441, 2487, 2493, 2516, 2570, 2840, 2850, 2890, 5395, 5531, 5534, 5535, 6150, 7002, 7009, 7030, 7034, 7038, 7080, 7090, 7100, 7130, 7170, 7211, 7500, 7550, 9070; Unpleasant: 3030, 3060, 3080, 3110, 3130, 3500,3530, 3550, 5971, 5972, 6250, 6260, 6350, 6370, 6510, 6540, 6560, 6610, 7359, 7380, 8230, 9265, 9301, 9340, 9373, 9470, 9480, 9600, 9611, 9620, 9622, 9630, 9830, 9911.

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16 Startle probes were 98 dB, 50 ms bursts of white noise generated by a Coulbourn S81-02 noise generator and gated by a Coulbourn S82-24 audio-mixer amplifier. Startles were delivered through E-A-RTONE 3A air conduction insert earphones (Aearo Company, Indianapolis, IN). One startle probe was presented per trial, resulting in 69 probes. Startle probes were presented 4.5, 10.5, or 16.5 s into the trial, which corresponds to 2.5 s into picture viewing for each picture position. Startle probes presented during pictures were equally distributed across each valence category. Shock was delivered through a concentric Tursky electrode placed on the participant’s inner right wrist. Shock was generated using a Grass S8800 Stimulator with an attached SIU7 Stimulus Isolation Unit (Grass Instruments, Quincy, MA). Participants received one shock (5 volts, 500 ms duration), which was delivered midway through the study during a threat trial. Based on preliminary work in our laboratory, this level of shock was rated by most participants as “highly annoying, but not painful.” Experimental stimuli were controlled by VPM software (Cook, 2001) on a Northgate IBM compatible CPU. VPM software was also used to collect and score all physiological measures. Appendix A contains the participant data file that specifies the parameters used in VPM for data reduction. The program file used for stimulus control and data collection is presented in Appendix B, and Appendix C contains the VPM program used for picture presentation. Procedure After obtaining informed consent for study participation, participants were seated in the testing room and completed questionnaires. Participants’ skin was then prepped for the physiological sensors by cleaning the areas with water and tissues (or rubbing

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17 alcohol in the case of the heart rate electrodes), and a small amount of electrolyte gel was rubbed into the skin over the orbicularis oculi and corrugator muscles. A small amount of electrolyte gel was also rubbed on the participants’ inner right wrist prior to shock electrode placement. Participants were then given study instructions, including which cue light signaled the possibility of shock and which cue light signaled no possibility of shock. Participants were also informed that shock would be delivered through the electrode on their right wrist, but were not specifically informed about the intensity of the shock. However, if participants asked about shock intensity, the experimenter repeated the information stated in the consent form that described the shock as “mildly painful, similar to a bee sting or needle prick.” Finally, the experimenter inserted earphones in the participant’s ears and dimmed the lights. The experiment began with four safe trials so that participants could become familiar with the procedure. These trials also served as startle habituation trials and thus were excluded from analysis. Without transition, 32 safe and 32 threat cues were presented (affective pictures were presented during half of these safe and threat trials). Trials were presented in a pseudorandom order with the requirement that no more than two trials of the same type (with respect to threat condition or picture presentation) could occur in a row. Shock was presented during a threat trial following trial 32 (this trial was excluded from analysis). After the experiment (approximately 25 minutes), physiological sensors were removed, and participants completed several questionnaires. Participants were then debriefed and thanked for their participation. The entire procedure lasted approximately two hours.

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18 Questionnaires The Dental Fear Survey (Kleinknecht et al., 1973; see Appendix D) consists of 20 items that assess dental fear on several dimensions: behavior (putting off or canceling appointments), physiology (e.g., tense muscles, increased respiration, etc), and feelings of anxiety (e.g., while sitting in the waiting room, feeling an injection into the gums, etc.). This measure is commonly used in research, and has a test-retest reliability of .73. A subset of 24 participants (12 high dental fear) also completed the Fear of Dental Pain questionnaire (van Wijk & Hoogstraten, 2003; see Appendix E), which instructs individuals to rate their fear of experiencing pain associated with several dental events, ranging from having a toothache or having a tooth pulled to being drilled in the jawbone or having some of their gum burned away. The scale consists of 18 items (scored 1-5; total range 18-90), and has high internal consistency (.93). The trait portion of State-Trait Anxiety Inventory (STAI-T; Spielberger, 1983; see Appendix F) was used to assess any possible differences in general anxiety between the two dental fear groups. Participants rate how often they generally agree with positively (e.g., “I am calm, cool, and collected”) and negatively phrased statements (e.g., “I feel nervous and restless”). The scale consists of 20 items rated 0-3, and higher scores indicate higher levels of general anxiety. The Mutilation Questionnaire (Klorman et al., 1974; see Appendix G) is a 30 item true-false scale (total range: 0-30) that assesses anxiety associated with injury, blood, and medical procedures. Items concern both self-injury (e.g., “I shudder when I think of accidentally cutting myself”), as well as injury of others (e.g., “If a badly injured person appears on TV, I turn my head away”).

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19 Participants also completed a post-experimental questionnaire designed to collect demographic information and assess several aspects of their experience in the experiment (see Appendix H). This included a 7-point Likert-type scale to rate the pleasantness–unpleasantness (anchored at 7 and 1, respectively) of their anticipation prior to and after receiving a shock, as well as experience of receiving the shock. Physiological Response Measurement and Reduction Startle Reflex The startle reflex was recorded using two Sensormedics 4 mm silver/silver chloride electrodes placed along the orbicularis oculi muscle under the left eye. Raw orbicularis oculi activity was sampled at 1000 Hz from 50 ms prior to probe onset to 250 ms after probe onset. Activity was filtered with a 90-250 Hz bandpass filter using a Coulbourn S75-01 bioamplifier, and the signal was integrated with a 200 ms time constant through a Coulbourn S76-01 contour-following integrator. Onset latency, peak latency, and peak magnitude were scored off-line using a scoring algorithm developed by Globisch, Hamm, Schneider, and Vaitl (1993). Trials with an onset latency of less than 20 ms were omitted from analysis. For each participant, startle magnitudes were z-score transformed, and then T-scores were calculated so that the mean of T-score distribution was set at 50. Each startle response is therefore expressed as a deviation from an individual’s own mean startle response. Skin Conductance Skin conductance was measured using two Sensormedics 10 mm silver/silver chloride electrodes filled with Unibase cream mixed with sodium chloride ( Fowles et al., 1981) that were placed over the hypothenar eminance of the left palm. A constant current (.5 v) was generated between the electrodes using a Coulbourn S71-22 coupler. Activity

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20 was acquired at 20 Hz, and half-second bins of mean skin conductance were calculated off-line. Skin conductance data were deviated from a 1 s baseline prior to cue onset. For the purpose of analyzing the skin conductance response to affective pictures, only the first picture in each trial was analyzed due to rapid picture presentation (i.e., 4 s viewing time and only 2 s inter-picture interval). Activity during the 4 s of picture viewing and the 2 s following picture presentation were deviated from a 1 s baseline prior to picture onset. Corrugator EMG Two Sensormedics 4 mm silver/silver chloride electrodes recorded corrugator muscle activity above the left eyebrow. Corrugator EMG was sampled at 20 Hz, and was filtered with a Coulbourn S75-01 bioamplifier using a 90-1000 Hz bandpass filter. The signal was integrated with a 500 ms time constant (Coulbourn S76-01 contour-following integrator), and half-second bins of median corrugator EMG were calculated off-line. Corrugator EMG was deviated from a 1s baseline prior to cue or picture onset. Heart Rate Heart rate was collected using Sensormedics 10 mm silver/silver chloride electrodes placed on participants’ forearms (Lead I configuration). Raw electrocardiogram activity was filtered with a Coulbourn S75-01 bioamplifier with a bandpass filter of 8-40 Hz. Interbeat intervals (R-wave spikes) were recorded with a Coulbourn S52-12 retriggerable one-shot. Interbeat intervals were converted off-line to heart rate in beats per minute (bpm), and were deviated from a 1 s baseline prior to cue or picture onset. All trials were individually examined to exclude trials contaminated with movement artifact (3.5%).

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21 Data Analysis For each physiological measure, mixed ANOVAs with dental fear group as a between-subject factor and one within-subject factor (threat of shock/safe condition) were conducted. A 2 x 2 x 2 (dental fear group x threat of shock/safe condition x picture/cue light only trials) mixed ANOVA was computed to determine if responses systematically varied by trial type. To examine picture valence effects, a 2 x 2 x 3 (dental fear group x threat of shock/safe condition x valence) mixed ANOVA was calculated. In addition, 2 x 2 x 2 (dental fear group x threat of shock/safe condition x pre/post shock period) were also calculated to determine if physiological responses changed over time. For analysis of continuously measured physiological responses (skin conductance, corrugator EMG, and heart rate), activity was averaged across the entire 20 s trial or 4 s of picture presentation. Student t-tests were employed to examine dental fear group differences in questionnaire data. All analyses were completed using Systat.

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22 CHAPTER 3 RESULTS Questionnaires Based on responses to the Dental Fear Survey, participants were divided into high dental fear (score > 60) and low dental fear groups. Based on this classification, the two groups did indeed differ on reported level of dental fear as expected (high: M=80.0, SD=11.54; low: M=40.18, SD=10.53), F (1, 36) = 122.18, p < .0001. The high dental fear group also reported significantly higher fear of dental pain (M=75.27, SD=10.94) than the low dental fear group (M=60.0, SD=10.89) as assessed with the Fear of Dental Pain questionnaire, F (1, 22) = 11.68, p = .003. High and low dental fear individuals reported similar levels of trait anxiety on the STAI-T (F < 1). High dental fear individuals endorsed greater distress associated with mutilation and injury on the Mutilation Questionnaire (M=14.87, SD=7.63) than low dental fear individuals (M=10.86, SD=5.17), although this difference was only marginally significant (F (1, 36) = 3.63, p =.06). Physiological Measures Mean activity for each for the four physiological measures by threat condition and dental fear group is presented in Table 3-1. In addition, data are further divided into responses to cue light only presentation and picture presentation for each valence. Startle Reflex Figure 3-1 illustrates mean startle magnitude for threat of shock and safe periods expressed as T-scores. Startle magnitude was larger under the threat of shock compared

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23 Table 3-1. Mean values of physiological activity by threat condition, dental fear group, and foreground context (mean activity across all trials, during cue light only trials, and during pleasant, neutral, and unpleasant pictures). Physiological Measure Condition Dental fear group All trials Cue light only Pleasant Neutral Unpleasant Startle t-score Safe Low 48.17 47.78 46.89 48.14 50.55 High 47.68 47.28 46.67 48.30 49.43 Threat of shock Low 51.84 51.71 50.18 53.54 52.82 High 52.31 52.74 50.59 51.85 53.24 Skin conductance Safe Low -0.09 -0.10 -0.07 -0.05 -0.02 microsiemens High -0.14 -0.16 -0.07 -0.05 -0.05 Threat of shock Low 0.02 0.02 0.14 -0.02 0.14 High 0.18 0.24 0.15 0.23 0.19 Corrugator EMG Safe Low -0.10 -0.56 0.18 0.28 0.50 microvolts High -0.19 -0.46 0.12 0.32 0.83 Threat of shock Low 0.26 -0.26 0.41 0.43 0.59 High 0.24 -0.10 0.23 0.36 1.02 Heart rate bpm Safe Low 0.31 0.46 -0.44 -0.44 -1.46 High -0.37 0.41 -0.45 -0.43 -0.91 Threat of shock Low 0.11 0.42 -0.67 -0.84 -0.86 High -0.59 -0.03 -1.08 -0.74 -1.09

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24 to safe periods, F (1, 36) = 94.08, p < .0001, and this effect was the same whether or not affective pictures were shown during the trial (F < 1). Mean startle onset latency was significantly shorter during threat of shock (M=38.76 ms) compared to safe periods (M=40.94 ms), F (1, 36) = 29.74, p < .0001. High and low dental fear individuals showed similar startle magnitudes and onset latencies (Fs < 1). When startle was analyzed using the untransformed data (raw A/D units), startle was also found to be larger under threat of shock (M=489.69 A/D units) compared to safe periods (M=394.72 A/D units), F (1, 36) = 50.30, p<.0001. Analysis using the untransformed startle data also confirmed that startle reactivity did not differ by level of dental fear (p=.3). Figure 3-1. Startle magnitude during threat of shock and safe periods. Startle magnitude decreased from preto post-shock exposure, F (1, 36) = 92.18, p < .0001, and this decrease after shock exposure interacted significantly with threat condition (F (1, 36) = 15.33, p < .0001). Although startle potentiation under threat of shock was smaller following shock exposure, the difference was still significant (F (1, 45 46 47 48 49 50 51 52 53 Safe Threat Magnitude (t-score)

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25 36) = 13.1, p < .001). This decrease in startle magnitude from preto post-shock periods reflects startle habituation that occurred across the experiment, rather than a decrease related to shock exposure itself. As Figure 3-2 illustrates, startle magnitude declined steadily throughout the experiment for both threat of shock and safe periods. Figure 3-2. Startle magnitude across the experiment. Each data point represents the mean startle magnitude during four successive threat of shock or safe trials. Startle magnitude was significantly modulated by picture valence, F (2, 72) = 12.72, p < .0001 (see Figure 3-3). Picture valence modulated the startle reflex similarly in high and low dental fear individuals (F < 1). During safe periods (no shock threat), picture valence modulated startle magnitude in a linear fashion (F (1, 36) = 29.74, p < .0001). Planned pairwise comparisons revealed that startle magnitude was significantly attenuated during pleasant compared to neutral pictures (F (1, 36) = 4.35, p = .04), and significantly potentiated during unpleasant compared to both neutral (F (1, 36) = 5.03, p = .03) and pleasant pictures (F (1, 36) = 29.74, p < .0001). Follow-up analyses showed 40 45 50 55 60 65 Magnitude (t-score) Safe Threat Pre-Shock Post-Shock

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26 that startle magnitude was larger during unpleasant picture viewing compared to the nopicture viewing context (i.e., when only the “safe” cue light was present, F (1, 36) = 9.56, p = .004), but not for neutral or pleasant pictures (p’s > .3). Figure 3-3. Startle magnitude by threat of shock condition and picture viewing context: pleasant, neutral, and unpleasant pictures, as well as the no-picture viewing context (cue light only trials). During threat of shock, startle magnitude was also modulated by picture valence in a linear manner (F (1, 36) = 7.86, p = .008). Pairwise comparisons indicated that startle magnitude was attenuated during pleasant picture viewing compared to both neutral (F (1, 36) = 5.29, p = .03) and unpleasant pictures (F (1, 36) = 7.86, p = .008), but that startle responses were similar during neutral and unpleasant pictures (F < 1). Compared to the no-picture viewing context (i.e., only the “threat” cue light), startle magnitude differed significantly only for pleasant pictures (F (1, 36) = 5.39, p = .03). Pleasant Neutral Unpleasant No pic 45 47 49 51 53 55 Safe Threat Picture Valence Magntiude (t-score)

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27 Skin Conductance Skin conductance was significantly modulated by threat condition (F (1, 35) = 35.99, p < .0001), and this effect was the same whether or not affective pictures were shown concurrently (F < 1). As Figure 3-4 illustrates, skin conductance increased during threat of shock compared to baseline, but decreased below baseline during safe periods. Skin conductance was not significantly modulated by picture valence (F < 1). Figure 3-4. Skin conductance during threat of shock and safe periods (expressed as a change from baseline in half second bins). Skin conductance responses differed significantly between the two dental fear groups (F (1, 35) = 4.65, p = .04), and this effect varied with threat condition (F (1, 35) = 8.46, p = .006). Figure 3-5 shows that the dental fear groups did not differ significantly in skin conductance reactivity during safe periods (p > .2), but the high dental fear group had larger skin conductance increases under the threat of shock compared to the low dental fear group (F (1, 35) = 11.58, p = .002). 20 15 10 5 0 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 Change (microsiemens) Time (s) Safe Threat

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28 Figure 3-5. Skin conductance by threat of shock condition and dental fear group (expressed as a change from baseline in half second bins). Threat of shock condition also interacted with pre-/post-shock phase, F (1, 35) = 27.78, p < .0001. Skin conductance increased during threat of shock compared to safe periods prior to shock exposure (F(1, 35) = 43.97, p < .0001) but not following shock exposure (p=.3). Much like startle magnitude, skin conductance responses habituated over time. As Figure 3-6 illustrates, skin conductance increased above baseline under threat of shock at the beginning of the experiment (first four threat trials), but then rapidly habituated. Dental fear group differences were also apparent in skin conductance responses over time (see Figure 3-7). Prior to shock exposure, both high and low dental fear individuals had larger skin conductance responses during threat of shock compared to safe periods (F (1, 15) = 36.12, p < .0001 and F (1, 20) = 10.14, p = .005, respectively). The high dental fear group continued to show significantly greater skin conductance Change (microsiemens) 20 15 10 5 0 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 Threat Safe High dental fear Low dental fear High dental fear Low dental fear Time (s)

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29 Figure 3-6. Skin conductance responses across the experiment. Each data point represents the mean skin conductance during four successive threat of shock or safe trials. Figure 3-7. Skin conductance by threat of shock condition, dental fear group, and pre-/ post-shock period. Mean responses during the pre-shock period are shown in the left panel, and those for post-shock period are shown in the right panel. -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 Change (micrsoiemens) Safe Threat Pre-Shock Post-Shock -0.25 -0.15 -0.05 0.05 0.15 0.25 0.35 Pre-Shock Post-Shock Change (microsiemens) High dental fear High dental fear Low dental fear Low dental fear * * * Safe Threat

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30 under the threat of shock compared to safe periods following shock exposure (F (1, 35) = 9.07, p = .009), whereas the low dental fear group stopped showing such differentiation (F < 1). Corrugator EMG Corrugator muscle activity was greater under the threat of shock compared to safe periods (F (1, 36) = 9.12, p = .005), and was also greater during picture viewing compared to trials when only the cue light was present (F (1, 36) = 30.97, p < .0001). As Figure 3-8 illustrates, muscle activity increased above baseline during picture viewing trials, and the greatest increase occurred during threat of shock (F (1, 36) = 9.4, p = .004). A different pattern emerged during trials in which only the cue light was present: corrugator muscle activity decreased below baseline, and muscle relaxation was more pronounced here for safe periods than during threat of shock (F (1, 36) = 6.62, p = .01). The high and low dental fear groups exhibited similar patterns of corrugator muscle activity (F < 1), and activity did not differ across the experiment (p = .2). As seen in Figure 3-9, corrugator EMG was significantly modulated by picture valence (F (1, 36) = 10.15, p < .0001). Pairwise comparisons revealed that corrugator EMG was significantly greater during unpleasant pictures compared to both pleasant and neutral pictures, both during threat of shock (F (1, 36) = 11.64, p = .002 and F (1, 36) = 6.35, p = .02, respectively) and safe periods (F (1, 36) = 9.33, p = .004 and F (1, 36) = 10.77, p = .002, respectively). Heart Rate Heart rate was not significantly modulated by shock threat (F < 1), nor did it change significantly across the experiment (p > .12). However, heart rate responses were modulated differently during cue light only and picture viewing trials (F (1, 35) = 10.75,

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31 Figure 3-8. Corrugator EMG by threat of shock condition and picture viewing context. Activity is expressed as a change from baseline in half second bins for picture viewing trials (top) and cue light only trials (bottom). Figure 3-9. Corrugator EMG by threat of shock condition and picture valence. 20 15 10 5 0 -1.00 -0.50 0.00 0.50 1.00 1.50 Time (s) Change (microvolts) picture + cue light cue light only Safe Threat Safe Threat 0.0 0.2 0.4 0.6 0.8 Change (microvolts) Picture Valence Pleasant Neutral Unpleasant Safe Threat

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32 p = .002): overall, heart rate decreased below baseline during picture viewing trials while it increased in cue light only trials (refer to Figure 3-10). Figure 3-10. Heart rate by threat of shock condition and picture viewing context. The left panel depicts heart rate change (bpm) during cue light only trials, while the right panel depicts picture viewing trials. The two dental fear groups showed different heart rate response patterns, F (1, 35) = 7.2, p = .01. Compared to baseline activity, high dental fear group showed an overall heart rate decrease (average response over the entire trial) while the low dental fear group showed heart rate increase (see Figure 3-11, top panel). Further analysis revealed that the dental fear groups differed in heart rate response during picture viewing trials (F (1, 35) = 8.0, p = .008), but not during cue light only trials (F < 1). As seen in Figure 3-11 (bottom panel), heart rate decreased during picture viewing trials for high dental fear individuals, but remained near baseline for the low dental fear individuals. Picture valence had a marginal effect on heart rate (F (1, 35) = 2.93, p = .06). Pairwise comparisons revealed that, during safe periods, unpleasant pictures prompted more deceleration compared to pleasant (F (1, 35) = 5.97, p = .02) and neutral (F (1, 35) = 5.89, p = .02) pictures. 20 15 10 5 0 -2 -1 0 1 2 Time (s) Change (bpm) Cue light only Safe Threat 20 15 10 5 0 -2 -1 0 1 2 Time (s) Change (bpm) Safe Threat Picture + cue light

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33 Figure 3-11. Mean heart rate change (bpm) by dental fear group (top panel), and by dental fear group as a function of picture viewing context (bottom panel). -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 High dental fear Low dental fear Safe Threat Change (bpm) -2 -1 0 1 2 Change (bpm) Safe Threat Pictures + cue light Cue light only High dental fear High dental fear Low dental fear Low dental fear

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34 Shock Ratings Prior to receiving a shock, participants rated shock anticipation as unpleasant (M=2.39, SD=1.03). However, after receiving a shock, participants rated their anticipation as significantly less unpleasant (M=3.47, SD=1.56), F (1, 37) = 14.04, p=.0006. This reduction in rated unpleasantness of shock anticipation differed by dental fear group (F (1, 36) = 4.4, p = .04): the low dental fear group reported a greater reduction in unpleasant anticipation than the high dental fear group. Of the participants who reported feeling the shock (n=31, 11 high dental fear), the experience of actually receiving the shock was rated as nearly neutral (M=3.61, SD=1.31), and there was no difference in shock ratings between the high and low dental fear groups (p=.2).

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35 CHAPTER 4 DISCUSSION Consistent with past research (Grillon et al., 1991; Grillon et al., 1993a; Grillon et al., 1993b), the startle reflex was potentiated and was elicited more quickly during shock anticipation compared to safe periods when shock was not possible. In addition, the finding that skin conductance responses were larger under the threat of shock replicates prior findings (Kopacz & Smith, 1971). The overall increase in skin conductance and corrugator muscle activity during threat of shock parallels physiological reactivity during the presentation of unpleasant pictures (e.g., Bradley et al., 2001a). This pattern of responding is consistent with the idea that anticipation of shock involves defense system activation and that shock anticipation is both arousing and aversive. More importantly, the current study examined the hypothesis that fear of pain is a key component of dental fear. Self-report data from the current study were consistent with this hypothesis: high dental fear individuals endorsed more fear of dental pain than low dental fear individuals. This hypothesis was also confirmed using physiological measures. During anticipation of a painful stimulus, high dental fear individuals exhibited more skin conductance than low dental fear participants. High dental fear individuals also continued to exhibit increased skin conductance following exposure to shock, whereas low dental fear individuals ceased showing this differentiation following exposure to the relatively mild shock. Following shock exposure, the low dental fear group also reported a greater reduction in unpleasant anticipation than the high dental fear group.

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36 These findings complement prior research examining physiological reactivity during anticipation of dental stimuli. High dental fear patients have larger skin conductance levels when seated in a dental operatory awaiting treatment compared to low dental fear patients (Caprara et al., 2003). Rather than examining anticipation of dental stimuli or dental pain, the current study used electric shock to tease apart whether high dental fear individuals are more physiologically reactive to anticipated pain in general. The enhanced skin conductance response in the high dental fear group suggests that high dental fear individuals may indeed be more fearful of pain. However, heart rate was not modulated by threat of shock in the current study, a result that has been reported previously in both threat of shock (Deane, 1961) and shock conditioning paradigms (Hamm et al., 1993). When the exact timing of a shock was indicated in advance to the participant (e.g., 10 seconds into the trial), Deane (1961) found that heart rate accelerated at the indicated time on the first trial, but decelerated at this time on subsequent trials. When participants did not know the exact timing of the shock and were not shocked on the first trial, heart rate change across the trial overlapped to a great extent with heart rate changes during a baseline, no-threat condition. These results suggest that heart rate modulation relies on both experience and temporal information during stimulus anticipation. In the current study, participants were not cued as to the timing of the shock and only received a mild shock several minutes into the experiment, which may account for the similarity of heart rate responses during threat of shock and safe periods. Hamm et al. (1993) found that heart rate accelerated in a shock conditioning paradigm during the acquisition phase, in which the to-be-conditioned cue (CS+) was followed by a shock (repeated eight times). The repeated shock exposure in

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37 this study differed from the current study in which shock threat was verbally induced and was not reinforced with shock until 12 minutes into the experiment. Indeed, Hamm and colleagues found no heart rate differences between the CS+ and a cue not paired with shock (CS-) in the extinction phase, in which shock did not follow the CS+. High and low dental fear participants showed different patterns of heart rate reactivity. During picture viewing trials, high dental fear individuals exhibited heart rate deceleration, while heart rate remained near baseline in the low dental fear group. Heart rate deceleration is indicative of attention to a stimulus (Graham & Clifton, 1966), suggesting that the high dental fear group showed a larger orienting response to picture stimuli. However, it must be pointed out that this is a relatively small change (a difference of only 1 beat per minute), which cautions against over-interpretation of this finding. High dental fear individuals did not exhibit heart rate acceleration during pain anticipation, which might have been predicted based on studies of phobics’ responses to their feared object (Hamm et al., 1997; Lundgren et al., 2001). However, these studies employed a perception paradigm (pictures or films), while the current study involved anticipation. It is also possible that there was no acceleratory “defense response” to the cue light since it predicted only the possibility of shock (which occurred only once), which is a step removed from actual painful stimulation. Unlike skin conductance and heart rate, startle magnitude and corrugator muscle activity did not differ between the dental fear groups, despite the fact that both of these measures were modulated by threat of shock. The startle results are not surprising in light of research suggesting that startle magnitude during anticipation varies by level of state anxiety, but not measures of trait anxiety or depression (Grillon et al., 1993a; Nitschke et

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38 al., 2002). In the current study, startle magnitude did not vary by dental fear, and the two dental fear groups had similar levels of trait anxiety. A self-report measure of state anxiety was not used in the current study, but should be included in future research as a manipulation check. Past research has shown that corrugator muscle activity does not condition as easily as the startle reflex and autonomic measures, perhaps because it can be more easily brought under voluntary control (Hamm et al., 1993). Similarly, facial muscles tend to be less active during anticipation as compared to perception (Bradley, 2000). In the current study, corrugator muscle activity increases were driven by affective picture presentation, and the two dental fear groups exhibited similar, appropriate corrugator EMG responses to unpleasant pictures. During trials in which no pictures were shown, corrugator muscle activity actually decreased below baseline (even though this relaxation was more pronounced during safe periods than threat of shock). These results suggest that the corrugator muscle is not activated in the absence of a specific aversive event. Rather, only in the context of an unpleasant picture stimulus was corrugator muscle activity greater during shock anticipation compared to safe periods. It is possible that the enhanced physiological reactivity of high dental fear individuals in anticipation of a painful stimulus is specific to the autonomic system. Or perhaps the autonomic system is a more sensitive index of fear that is recruited at lower levels of fear. Perhaps if a range of shock intensities (and thus presumably a range of fear levels) were employed, dental fear differences might emerge in other physiological systems. With respect to this point, it is of note that high and low dental fear participants did not differ in their retrospective ratings of initial shock anticipation aversiveness (rated

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39 mildly unpleasant by both groups). It is also noteworthy that our high dental fear sample was comprised of college students, who more than likely exhibit less distress and interference than dental phobics seeking treatment for their phobia. Further research is needed to investigate these possibilities. Affective picture perception in the current study prompted physiological modulation consistent with past research (see Bradley et al., 2001a, for a review). Unpleasant pictures occasioned increased corrugator muscle activity, and greater heart rate deceleration was evident during unpleasant compared to pleasant and neutral pictures during periods of safety from shock. Startle was potentiated during unpleasant picture viewing compared to pleasant pictures, although different patterns of responding emerged during threat of shock and safe periods. During safe trials, only startle magnitude during unpleasant pictures differed significantly from a no-picture context–in this case startle was potentiated. In contrast, only startle magnitude during pleasant pictures differed from the no-picture context while under the threat of shock–here the startle reflex was inhibited. Thus it appears that the context–shock anticipation or safety from shock–overrode transient affective modulation. When the context was aversive (shock anticipation), responding was modulated only by a pleasant event, while in a comparatively pleasant or relieving context (safety from shock) responding was modulated only by an unpleasant event. One issue that arises is that our sample was comprised entirely of female volunteers, and it is possible that males may show a different pattern of physiological reactivity during shock anticipation. To begin, females tend to report more dental fear than males (Kleinknecht et al., 1973; ter Horst & de Wit, 1993), although fear of pain

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40 appears to be a strong predictor of dental fear in both males and females (Liddell & Locker, 1997; McNeil & Berryman, 1989). Kopacz and Smith (1971) found that females had larger skin conductance levels during shock threat and a greater number of skin conductance responses across shock threat periods than males. In affective picture processing studies, females tend to rate unpleasant contents more negative and arousing than males, and also tend to show more heightened physiological reactivity to unpleasant contents than males (Bradley et al., 2001b). A number of recent reviews also suggest that there are gender differences in pain perception and sensitivity: females tend to show greater pain sensitivity, both in clinical pain conditions (Unruh, 1996) and experimentally induced pain (Dao & LeResche, 2000; Riley et al., 1998). The experimental paradigm presented in this paper is currently being employed to examine male participants, which will provide needed information about possible gender differences in physiological reactivity during shock anticipation as well as possible interactions with dental fear. An alternative interpretation of the current results is that the physiological patterns found may reflect increased general anticipation during threat of shock, not fearful or aversive anticipation per se. Participants were instructed that a stimulus (shock) was possible whenever the threat cue light was present, but no stimulus was anticipated when the safe light was present. Past research has demonstrated startle potentiation during anticipation of non-aversive stimuli, indicating that startle may be potentiated during attention or anticipation in addition to during perception of unpleasant stimuli. For example, Lipp (2002) found that startle was potentiated during anticipation of a reaction time task compared to trials that cued no upcoming reaction time task.

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41 Startle potentiation has also been found during anticipation of pleasant stimuli. In a paradigm in which snake phobics were cued to upcoming slides of snakes or erotica, startle was similarly potentiated during anticipation of snakes and erotica compared to neutral pictures (Sabatinelli et al., 2001). Using a lottery-type task, Skolnick and Davidson (2002) found that startle was potentiated during anticipation of feedback regarding a possible monetary win compared to trials in which participants were cued that winning money was not possible. Importantly, this effect was similar to startle potentiation during anticipation of an aversive loud noise compared to trials in which no noise was possible. Grillon and his colleagues (1993b) did include a control study to examine this alternative interpretation. Instead of electric shock, these participants anticipated a barely perceptible non-painful tactile stimulus. Grillon found that startle magnitude did not differ between attend (akin to “threat”) and no-attend (“safe”) periods. While controlling for the tactile stimulation and anticipation aspects of threat of shock, this task was not as engaging as the lottery-type task described above. A follow-up study is currently underway in our laboratory that assesses physiological reactivity in a paradigm that blends Grillon’s methodology with a more engaging task: participants are instructed that one cue indicates that vibrotactile stimulation is possible, and that they will win money for each vibration they feel. This “threat of reward” study will provide a closer look at startle modulation and physiological reactivity during anticipation of an arousing, nonaversive event. If we do find that startle is potentiated during the “threat of reward,” this may explain why dental fear differences were not found in startle reactivity during threat

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42 of shock. This would indicate that attention or general anticipation was the critical factor modulating startle. On the other hand, this generalized arousal interpretation is unlikely in the current study, which included additional physiological measures indexing fear and aversivesness. For instance, corrugator muscle activity was overall greater during threat of shock compared to safe periods, suggesting that shock anticipation was indeed unpleasant. Moreover, this hypothesis would also fail to account for the greater skin conductance seen in the high dental fear group, which is presumably mediated by differences in fearfulness. It seems unlikely that high dental fear individuals would be more aroused than low dental fear individuals during anticipation of neutral, pleasant, or fear-irrelevant unpleasant stimuli, although this hypothesis has not been tested. The threat of shock paradigm in the current study prompted physiological reactivity consistent with prior research and the notion of defense system activation. During anticipation of a painful stimulus, high and low dental fear individuals differed in physiological reactivity, with the high dental fear group exhibiting a larger increase in skin conductance. These data are consistent with literature suggesting high dental fear individuals report more fear of pain, and also show greater skin conductance preceding dental treatment than low dental fear individuals (Caprara et al., 2003). This finding is striking given that the painful stimulus employed in the current study was not related to dental or orofacial pain, nor did the study employ any stimuli related to dental treatment. In addition, the shock was mild and was only delivered once during the experiment. The physiological responses elucidated during anticipation of pain complement the current

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43 literature regarding experience, expectations, and memories of pain in individuals with dental fear.

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44 APPENDIX A DEFAULT.VPM FILE /SESSION= T,999,9999,'C:','ABC'. /VPMANLOG=1. segment. append=2. repeat=69. copy(1,2). kmult(2)=0.01. ksum(2)=20. dstat(2,3)= 201, 0.0, 0.0, 0.5,mean,'(8f8.3)'. /VPMANLOG=2. segment. append=2. repeat=69. copy(1,2). kmult(2)=0.01626. dstat(2,3,4)= 202, 0.0, 0.0, 0.5,median,'(8f8.3)'. /VPMANLOG=3. segment. append=2. repeat=69. copy(1,2). kmult(2)=0.01626. dstat(2,3,4)= 203, 0.0, 0.0, 0.5,median,'(8f8.3)'. /VPMEVENT=0. segment. append=2. repeat=69. edit(1,2)=25,450,1500,0.6,1.7. dstat(1,2)= 208,0.0,0.0,0.5,mean,'((10f10.3))'. /VPMANLOG=16. segment. repeat=207. kcopy(3)=800,1. copy(1,2)=51,351,1,1. copy(3,2)=1,1,1,301. OKMISSING. eyeblink(2)= 222,21,250,300,95,50,10,25,0,2047. /VPMANLOG=5. segment.

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45 repeat=207. kcopy(3)=800,1. copy(1,2)=51,351,1,1. copy(3,2)=1,1,1,301. rectify(2)=1. iirfilter(2)=.0487569,1,.9046863,50. eyeblink(2)=223,21,250,300,95,50,10,25,0,2047. /vpmsort input= a01,a02,a03. output= ana. format='(20(7f8.3/))'.

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46 APPENDIX B PHYSIO1.VPM FILE Title threat EEG; fall 2003; Order 1 Include c:\vpm\library.vpm Include c:\vpm\cookmacs.vpm ; ; one millisec time base, and take integ+raw startle ; kticks equ 1000 BEGINDCA kticks,50,start include c:\vpm\labmast.drv ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; constants + lists of timing durations and startle trials ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; k4: dw 4 k5: dw 5 k28: dw 28 k32: dw 32 serport equ 3f8h zero: dw 0 tenth: dw 100 twohun: dw 200 five: dw 5 tensec: dw 10000 one: dw 1 two: dw 2 three: dw 3 four: dw 4 six: dw 6 onesec: dw 1000 twosec: dw 2000 foursec: dw 4000 fivesec: dw 5000 sixsec: dw 6000 sevensec: dw 7000 eightsec: dw 8000 twenty: dw 20 threesec: dw 3000 halfsec: dw 500 shifts: dw 3 temp: dw ?

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47 signal: dw ? threat: dw ? ocond: dw ? onehun: dw 100 strdel: dw 300 numtrls: dw ? ;36 in phase 1, 68 in phase 2 prestrtl: dw 50 postrtl: dw 200 noisdur: dw 50 picstr: dw 2450 strrest: dw 1200 ; 2450+350str+200=4000 ms fullv: dw 4000 ; no startle trials btime: dw 18000 brest: dw ? tcond: dw ? pcond: dw ? tbit: dw ? tstr: dw ? resttr: dw ? piccnt: dw ? ten: dw 10 twofifty: dw 250 lastr: dw 68 ; 4 practice + 32 trials ; safe or threat condition: 1 or 2 cond: dw 1,1,1,1 ;str Hab, 4 safe trials, 2 pic 2 ITI dw 2,1,2,1 ;Ord1 dw 2,1,2,1 ;Ord1 dw 1,2,2,1 ;Ord1 dw 1,2,1,2 ;Ord1 dw 2,1,1,2 ;Ord1 dw 1,2,1,2 ;Ord1 dw 1,2,2,1 ;Ord1 dw 2,1,1,2 ;Ord1 dw 2,1,2,1 ;Ord1 dw 2,1,2,1 ;Ord1 dw 1,2,2,1 ;Ord1 dw 1,2,1,2 ;Ord1 dw 2,1,1,2 ;Ord1 dw 1,2,1,2 ;Ord1 dw 1,2,2,1 ;Ord1 dw 2,1,1,2 ;Ord1 ; pic or iti condition: 1 or 2 cond2: dw 1,2,2,1 ;str Hab: 2 pic, 2 ITI dw 1,2,2,1 ;Ord1 dw 2,1,1,2 ;Ord1 dw 2,1,2,1 ;Ord1

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48 dw 1,2,2,1 ;Ord1 dw 2,1,2,1 ;Ord1 dw 2,1,1,2 ;Ord1 dw 1,2,1,2 ;Ord1 dw 1,2,1,2 ;Ord1 dw 1,2,2,1 ;Ord1 dw 2,1,1,2 ;Ord1 dw 2,1,2,1 ;Ord1 dw 1,2,2,1 ;Ord1 dw 2,1,2,1 ;Ord1 dw 2,1,1,2 ;Ord1 dw 1,2,1,2 ;Ord1 dw 1,2,1,2 ;Ord1 ; strlist = number of pic on trial on which to startle strlist: dw 2,1 ;str hab dw 2,2 ;order 1 dw 2,1 ;order 1 dw 1,3 ;order 1 dw 1,2 ;order 1 dw 3,1 ;order 1 dw 3,1 ;order 1 dw 1,2 ;order 1 dw 3,2 ;order 1 dw 2,3 ;order 1 dw 3,3 ;order 1 dw 2,2 ;order 1 dw 3,3 ;order 1 dw 1,3 ;order 1 dw 2,2 ;order 1 dw 3,1 ;order 1 dw 1,1 ;order 1 ; ititimes c1 equ 2450 ; str during pic1 c2 equ 8450 ; pic2 c3 equ 14450 ; pic3 itistr: dw ? itilist: dw c2,c3 ;str Hab dw c1,c3 ;Ord1 dw c2,c2 ;Ord1 dw c3,c1 ;Ord1 dw c1,c3 ;Ord1 dw c2,c2 ;Ord1 dw c1,c3 ;Ord1 dw c3,c1 ;Ord1 dw c2,c2 ;Ord1 dw c1,c3 ;Ord1

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49 dw c2,c2 ;Ord1 dw c3,c1 ;Ord1 dw c1,c3 ;Ord1 dw c2,c2 ;Ord1 dw c1,c3 ;Ord1 dw c3,c1 ;Ord1 dw c2,c2 ;Ord1 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Digital outputs ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; noise: dw 4 ;noise on bit 2 of DO macinfo: dw 49 egipic: dw 144 EGIbit: dw 128 picbit: dw 16 eegstr: dw 36 tonestr: dw 5 egicond: dw 8 shockbit: dw 1 ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; sampling table ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; sampslo: antable 6 ;sample 5 channels anrow 0,,@adbuf0,,1,8,,,brYellow anrow 1,,@adbuf1,50,2,8,,,brGreen anrow 2,,@adbuf2,50,3,8,,,brRed anrow 3,,@adbuf3,50,4,8,,,brBlue anrow 4,,@adbuf4,,5,8,,,brWhite anrow 5,,@adbuf5,,6,8,,,brwhite sampfast: antable 7 ;sample 7 channels anrow 0,,@adbuf0,,1,8,,,brYellow anrow 1,,@adbuf1,50,2,8,,,brGreen anrow 2,,@adbuf2,50,3,8,,,brRed anrow 3,,@adbuf3,50,4,8,0,2048,brBlue anrow 4,,@adbuf4,1,5,8,,,brWhite anrow 5,,@adbuf5,1,6,8,,,brWhite anrow 16,,@adbuf3,1,7,8,0,2048,brRed texttbl: texttable 17,5 textrow 'UserCount:', 1, 1,2,@usrcnt,,,15,pos16bit textrow 'ASE Clock:', 1,21,2,@aseacc,,,15,pos16bit textrow 'Threat:', 1,36,2,tcond,,,15,pos16bit textrow 'PicCond:', 1,50,2,pcond,,,15,pos16bit textrow 'Pic#:' 1,65,2,piccnt,,,15,pos16bit textrow 'UserClock:', 2, 1,2,@usrclk,,,15,pos16bit

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50 textrow 'Last Time:', 2,21,2,@asetime,,,15,pos16bit textrow 'StrNum: ', 2,65,2,tstr,,,15,pos16bit textrow 'Delay: ', 3, 1,2,@delay,,,15,pos16bit textrow 'LastEvent:', 3,21,2,@lastase,,,15,bin16bit textrow 'NumTrls:', 3,52,2,numtrls,,,15,pos16bit textrow 'EKG/0', 4, 1,brYellow,@adbuf0,5,1,,sign12bit textrow 'SCL/1', 4,16,brGreen,@adbuf1,5,16,,sign12bit textrow 'Corr/2' 4,30,brRed,@adbuf2,5,30,,sign12bit textrow 'Blk/3', 4,46,brBlue,@adbuf3,5,46,,sign12bit textrow 'Raw1/4', 4,61,brWhite,@adbuf4,5,61,,sign12bit textrow 'Raw2/5', 4,68,brWhite,@adbuf5,6,61,,sign12bit ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; macro to turn on the shutter Shutron macro portout k5,serport delay one portout k28,serport delay one portout zero,serport delay one endm ; macro to turn off the shutter Shutroff macro portout k5,serport delay one portout k32,serport delay one portout zero,serport delay one endm ; macro to do advance SADVANC MACRO PORTOUT K5,serport DELAY ONE PORTOUT ZERO,serport DELAY ONE PORTOUT ZERO,serport DELAY ONE ENDM ; macro to do reverse Sreverse macro PORTOUT K5,serport DELAY ONE PORTOUT K4 ,serport DELAY ONE PORTOUT ZERO,serport

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51 DELAY ONE ENDM ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;define a macro which presents a startle using a variable bit combo startle macro ; message strmsg setantable sampfast delay prestrtl portout eegstr,71dh ; EEG + Str trigger delay noisdur portout zero,71DH delay twofifty ;50+50+250=350 ms total setantable sampslo ; message stroff endm ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; messages to the experimenter ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; strmsg: deftext "startle on" stroff: deftext "startle off" shiftmsg: deftext "press shift to begin a block" endmsg: deftext "experiment completed" pretrial: deftext "pre trial baseline" picblk: deftext " PICTURE block" nopicblk: deftext " NO PICTURE block" endblk: deftext "Block Over" startblk: deftext "Block Starting" shocktr: deftext "Shock trial" ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; start: setantable sampslo delay onesec settexttable texttbl delay onesec asemask 1 ;read HR on digital input setcount zero delay halfsec shutroff portout zero,71dh mshift: message shiftmsg ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; display physiological channels until shift is pressed ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; waitloop: delay tenth

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52 peek kbdstat,0,temp BITmask shifts,temp jumpeq zero,temp,waitloop ; here is the main loop copy one,ocond ; start on safe ; to make sure projector gets to right spot sadvanc ;slide projector on safe slide... icopy 36,numtrls ; 4 practice + 32 normal mainloop:upcount clockreset message startblk copy zero,piccnt get cond,2,tcond,0 ;get threat condition (1 of 2) jumpeq tcond,one,safe ;1=safe 2=threat copy two,threat ; code trial jumpeq tcond,ocond,doblock ; same cond as last, no need to ch tray sadvanc ; otherwise, change jump doblock ;now, cue it safe: copy one,threat ;cod trial jumpeq tcond,ocond,doblock ; old cond was same; no need to ch tray sreverse ; change tray doblock: dcstart ;start dc 2 s prior to each block delay twosec cue: copy tcond,ocond ; save threat cond for next trial portout egicond,71dh ; trigger to EGI shutron ; indicate threat condition delay ten ; delay 10 ms portout zero,71dh ; trigger off; light on/off remains delay twosec ; two seconds with just cue get cond2,2,pcond,0 jumpeq two,pcond,doITI ; no pics condition get strlist,2,tstr,0 ;find out when to startle message picblk dopic: sum one,piccnt copy fullv,resttr ;default is 4 s viewing portout egipic,71dh ;trigger to EGI and to pic machine delay ten portout zero,71dh ;trigger off jumpne tstr,piccnt,finish ; no startle on this pic delay picstr ;delay for str startle copy strrest,resttr finish: delay resttr delay twosec ;delay ITI jumpne piccnt,three,dopic ;3 pics per block, do next pic jump stopit ; else start new block

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53 doITI: message nopicblk copy btime,brest get itilist,2,itistr,0 ; find where to startle on this ITI block delay itistr ; delay startle ; startle subtract itistr,brest delay brest stopit: shutroff message endblk dcstop write next: jumplt @usrcnt,numtrls,mainloop ; if usrcnt=36 then will do do shock jumpeq numtrls,lastr,endit ; if numtrls=68, it's over... shock: message shocktr copy two,tcond jumpeq tcond,ocond,stim chth2: sadvanc stim: dcstart delay twosec portout egicond,71dh shutron delay sixsec portout shockbit,71dh delay twenty portout zero,71dh delay fivesec startle delay sevensec dcstop copy two,ocond b2: icopy 68,numtrls jump mainloop ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; endit: message endmsg delay twosec exit enddca vpm ends end program

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54 APPENDIX C PIC1.VPM FILE Title MAIN PICTURE PROGRAM (show pics for 4 sec); Order 1 Include c:\vpm\library.vpm Include c:\vpm\cookmacs.vpm ; kticks equ 1000 BEGINDCA kticks,50,start Include c:\vpm\nointer.drv ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; constants + lists of timing durations ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; k0: dw 0 k1: dw 1 pport: dw 379h k24: dw 24 k2: dw 2 macbit: dw 49 temp: dw ? twofifty: dw 250 zero: dw 0 tenth: dw 100 twohun: dw 200 one: dw 1 two: dw 2 five: dw 5 six: dw 6 shifts: dw 3 piccnt: dw ? numpics: dw 102 ; 96 pics + 6 trials... 102 sechalf: dw 1500 onesec: dw 1000 twosec: dw 2000 fivesec: dw 5000 vidmode: dw 115h halfsec: dw 500 tensec: dw 10000 pictime: dw 4000 ;pics presentation (4 sec on) bit32: dw 32 ;digital input bit 5 from Tower (to show pics) bit128: dw 128 iti: dw ?

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55 onemin: dw 60000 order: dw 111 ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; picture order presentation, VERSION 2 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; bmplst: deftext '7090.bmp' deftext '9340.bmp' deftext '7260.bmp' deftext '4659.bmp' deftext '6540.bmp' deftext '2210.bmp' deftext '8230.bmp' ;order1 deftext '4800.bmp' ;order1 deftext '2191.bmp' ;order1 deftext '8531.bmp' ;order1 deftext '7130.bmp' ;order1 deftext '5971.bmp' ;order1 deftext '5621.bmp' ;order1 deftext '6260.bmp' ;order1 deftext '2840.bmp' ;order1 deftext '7380.bmp' ;order1 deftext '7270.bmp' ;order1 deftext '7038.bmp' ;order1 deftext '2393.bmp' ;order1 deftext '4681.bmp' ;order1 deftext '3060.bmp' ;order1 deftext '3030.bmp' ;order1 deftext '2570.bmp' ;order1 deftext '4680.bmp' ;order1 deftext '7350.bmp' ;order1 deftext '9630.bmp' ;order1 deftext '7211.bmp' ;order1 deftext '9830.bmp' ;order1 deftext '6150.bmp' ;order1 deftext '8501.bmp' ;order1 deftext '2890.bmp' ;order1 deftext '8186.bmp' ;order1 deftext '6370.bmp' ;order1 deftext '7230.bmp' ;order1 deftext '5395.bmp' ;order1 deftext '9911.bmp' ;order1 deftext '8179.bmp' ;order1 deftext '2487.bmp' ;order1 deftext '6510.bmp' ;order1

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56 deftext '9480.bmp' ;order1 deftext '5531.bmp' ;order1 deftext '8170.bmp' ;order1 deftext '2383.bmp' ;order1 deftext '3500.bmp' ;order1 deftext '8490.bmp' ;order1 deftext '7030.bmp' ;order1 deftext '9620.bmp' ;order1 deftext '5260.bmp' ;order1 deftext '2214.bmp' ;order1 deftext '3110.bmp' ;order1 deftext '4650.bmp' ;order1 deftext '5534.bmp' ;order1 deftext '8162.bmp' ;order1 deftext '9611.bmp' ;order1 deftext '2850.bmp' ;order1 deftext '4690.bmp' ;order1 deftext '3550.bmp' ;order1 deftext '6610.bmp' ;order1 deftext '7460.bmp' ;order1 deftext '7100.bmp' ;order1 deftext '8185.bmp' ;order1 deftext '7550.bmp' ;order1 deftext '6350.bmp' ;order1 deftext '7002.bmp' ;order1 deftext '5849.bmp' ;order1 deftext '9600.bmp' ;order1 deftext '9265.bmp' ;order1 deftext '2190.bmp' ;order1 deftext '4810.bmp' ;order1 deftext '3130.bmp' ;order1 deftext '4660.bmp' ;order1 deftext '2516.bmp' ;order1 deftext '5535.bmp' ;order1 deftext '7359.bmp' ;order1 deftext '5910.bmp' ;order1 deftext '7289.bmp' ;order1 deftext '9373.bmp' ;order1 deftext '7500.bmp' ;order1 deftext '3530.bmp' ;order1 deftext '8030.bmp' ;order1 deftext '2493.bmp' ;order1 deftext '7034.bmp' ;order1 deftext '5972.bmp' ;order1 deftext '8502.bmp' ;order1 deftext '8178.bmp' ;order1

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57 deftext '6250.bmp' ;order1 deftext '2441.bmp' ;order1 deftext '7080.bmp' ;order1 deftext '9301.bmp' ;order1 deftext '8500.bmp' ;order1 deftext '8370.bmp' ;order1 deftext '6560.bmp' ;order1 deftext '2200.bmp' ;order1 deftext '9622.bmp' ;order1 deftext '7170.bmp' ;order1 deftext '7450.bmp' ;order1 deftext '4670.bmp' ;order1 deftext '3080.bmp' ;order1 deftext '9070.bmp' ;order1 deftext '7330.bmp' ;order1 deftext '7009.bmp' ;order1 deftext '9470.bmp' ;order1 ; texttbl: texttable 11,3 textrow 'UserCount:', 1, 1,2,@usrcnt,,,15,pos16bit textrow 'spawnret1', 1,21,2,@spawnret1,,,15,pos16bit textrow 'Nscreens', 1,52,2,@nscreens,,,15,pos16bit textrow 'bmpfile: ', 1,69,2,bmplst,,,15,pos16bit textrow 'pport', 2, 1,2,temp,,,15,bin16bit textrow 'Order', 2,21,2,order,,,15,pos16bit textrow 'joycentr:', 2,52,2,@joycenter,,,15,sign12bit textrow 'Oflow:', 2,69,2,@oflow,,,15,pos16bit textrow 'Delay: ', 3, 1,2,@delay,,,15,pos16bit textrow 'LastEvent:', 3,21,2,@lastase,,,15,bin16bit textrow 'Store:', 3,52,2,@storecount,,,15,pos32bit ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; messages to the experimenter ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; endmsg: deftext "experiment completed" gotbit: deftext "got bit" ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; start: delay tenth settexttable texttbl ;set texttable delay tenth setcount zero ;sets the VPM counter to 0 delay tenth delay onesec ;

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58 collect: clockreset ;resets the clock to 0 icopy 2,@edispblank ;turn off physio display reset ispawn wait11 ;spawned commands coming, next label= waitl setvesamode vidmode ;set video mode endblock ;log '@spawnret1=', @spawnret1 wait11: delay one ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; copy zero,piccnt ;set piccnt to 0; picloop: upcount clockreset ;resets the clock to 0 jumpeq @usrcnt,one,doit setsvga: sum one,piccnt ; delay one ispawn waits ;spawned commands coming, next label= waitbit openbmp_l bmplst ;open pic file loadbmp k0 ;load pic file log '@spawnret1=',@spawnret1 endblock waits: waitspawn waitbit: delay one portin 379h,temp ;get bit 5 from Tower to show pic bitmask bit32,temp ;look at a bit pattern (bit 5) jumpeq zero,temp,waitbit ;if temp=0 then remain into waitbit loop doit: vesascreen k0 ;show pic (12 sec) delay pictime ;pic remains for 12 sec vesascreen k1 ;turn off pic ; delay halfsec ;delay 500 ms ; message gotbit next: jumplt piccnt,numpics,picloop ;if piccnt < numpics then remain into picloop (56 pics) ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; delay fivesec ;delay endmsg until physio ends delay onemin over: message endmsg delay twosec exit enddca vpm ends end program

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59 APPENDIX D DENTAL FEAR SURVEY Please use the following scale for questions 1 & 2. 1 2 3 4 5 Never Once or twice A few times Often Nearly every time 1. Has fear of dental work ever caused you to put off making an appointment? 2. Has fear of dental work ever caused you to cancel or not appear for an appointment? Please use the following scale for questions 3-20. 1 2 3 4 5 Not at all A little Somewhat Much Very Much When having dental work done 3. My muscles become tense. 4. My breathing rate increases. 5. I perspire. 6. I feel nauseated and sick to my stomach. 7. My heart beats faster. Please rate how much fear, anxiety, or unpleasantness each situation below causes you. 8. Making an appointment for dentistry. 9. Approaching the dentist’s office. 10. Sitting in the waiting room. 11. Being seated in the dental chair. 12. The smell of the dentist’s office. 13. Seeing the dentist walk in. 14. Seeing the anesthetic needle. 15. Feeling the needle injected. 16. Seeing the drill. 17. Hearing the drill. 18. Feeling the vibrations of the drill. 19. Having your teeth cleaned. 20. All things considered, how fearful are you of having dental work done?

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60 APPENDIX E FEAR OF DENTAL PAIN QUESTIONNAIRE Instructions: The items below describe painful experiences. Please look at each item and think about how FEARFUL you are of experiencing the PAIN associated with each item. If you have never experienced the PAIN of a particular item, please answer on the basis of how FEARFUL you expect you would be if you had such an experience. Use the following scale to rate your FEAR OF PAIN . 1 2 3 4 5 not at all a little a fair amount very much extreme I FEAR the PAIN associated with: 1. Receiving an anesthetic in the mouth. 2. Having some gum burned away. 3. The dentist's hook that gets stuck behind a filling. 4. Having a lump cut open in the mouth. 5. The filling of a molar. 6. Receiving a root canal treatment. 7. Having a tooth pulled. 8. A cold sensation in the mouth close to a cavity. 9. An incision in the gums. 10. An old filling that's been removed. 11. Being drilled in the jawbone. 12. Being drilled in a tooth. 13. A cavity that's been explored with the dentist's hook. 14. Receiving an injection in the roof of the mouth. 15. Braces that are being tightened. 16. Having a wisdom tooth extracted. 17. A severe toothache. 18. A cavity that's being excavated with a rude drill.

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61 APPENDIX F STATE-TRAIT ANXIETY INVENTORY (STAI-T) A number of statements which people have used to describe themselves are given below. Read each statement and then blacken in the appropriate circle to indicate how you generally feel. There are no right or wrong answers. Do not spend too much time on any one statement but give the answer which seems to describe how you generally feel. 0=Almost never 1=Sometimes 2=Often 3=Almost always 1. I feel pleasant. 2. I feel nervous and restless. 3. I feel satisfied with myself. 4. I wish I could be as happy as others seem to be. 5. I feel like a failure. 6. I feel rested. 7. I am "calm, cool, and collected". 8. I feel that difficulties are piling up so that I cannot overcome them. 9. I worry too much over something that really doesn't matter. 10. I am happy. 11. I have disturbing thoughts. 12. I lack self-confidence. 13. I feel secure. 14. I make decisions easily. 15. I feel inadequate. 16. I am content. 17. Some unimportant thought runs through my mind and bothers me. 18. I take disappointments so keenly that I can't put them out of my mind. 19. I am a steady person. 20. I get in a state of tension or turmoil as I think over my recent concerns and interests.

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62 APPENDIX G MUTILATION QUESTIONNAIRE Try to decide whether “true” or “false” most represents your feelings as associated with your most recent thoughts or experiences, then fully darken the appropriate circle on your answer sheet. Remember that this information is completely confidential and will not be made known to your instructor. Work quickly and don’t spend much time on any question. We want your first impression on this questionnaire. Now go ahead, work quickly, and remember to answer every question. 1=true, 2=false 1. I could not remove the hook from a fish that was caught. 2. I would feel some revulsion looking at a preserved brain in a bottle. 3. If a badly injured person appears on TV, I turn my head away. 4. I dislike looking at pictures of accidents or injuries in magazines. 5. I do not mind visiting a hospital and seeing ill or injured persons. 6. Medical odors make me tense and uncomfortable. 7. I would not go hunting because I could not stand the sight of a dead animal. 8. Watching a butcher at work would make me nervous. 9. A career as a doctor or nurse is very attractive to me. 10. I would feel faint if I saw someone with a wound in the eye. 11. Watching people use sharp power tools makes me nervous. 12. The prospect of getting an injection or seeing someone else get one bothers me quite a bit. 13. I feel sick or faint at the sight of blood. 14. I enjoy reading articles about modern medical techniques. 15. Injuries, accidents, blood, etc., bother me more than anything else. 16. Under no circumstances would I accept an invitation to watch a surgical operation. 17. When I see an accident I feel tense. 18. It would not bother me to see a bad cut as long as it had been cleaned and stitched. 19. Using very sharp knives makes me nervous. 20. Not only do cuts and wounds upset me, but the sight of people with amputated limbs, large scars, or plastic surgery also bothers me. 21. If instruments were available, it would be interesting to see the action of the internal organs in a living body. 22. I am frightened at the idea of someone drawing a blood sample from me. 23. I don’t believe anyone could help a person with a bloody wound without feeling at least a little upset. 24. I am terrified by the idea of having surgery.

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63 25. I am frightened by the thought that I might someday have to help a person badly hurt in a car wreck. 26. I shudder when I think of accidentally cutting myself. 27. The sight of dried blood is repulsive. 28. Blood and gore upset me more than the average person. 29. The sight of an open wound nauseates me. 30. I could never swab out a wound.

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64 APPENDIX H POSTEXPERIMENTAL QUESTIONNAIRE Subject #_____________ Semester/Year__________ IRB#_______________ Experimenters:___________________________________________________ 1. Age _______ 2. Year in school _________________ 3. Gender (circle one): Male Female 4. Ethnicity (circle one): White African-American Hispanic Asian Other:_________ 5. Handedness: Lefthanded Righthanded Ambidextrous 6. Do you wear glasses or contact lenses? Yes No Were you wearing them during the experiment? Yes No 7. Do you have any hearing loss or problems hearing? Yes No If so, please describe which ear and the extent of damage: ____________________________________ 8. Please rate the pleasantness or unplesantness of the following events using the following scale: 1 2 3 4 5 6 7 unpleasant pleasant Your anticipation of receiving a shock before you were shocked _____ Your anticipation of receiving a shock after initally being shocked _____ Actually receiving the shock _____ The noises heard over the headphones _____ Wearing the sensors under your eye _____ Viewing picures of violence _____ Viewing mutilation pictures _____

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65 1 2 3 4 5 6 7 unpleasant pleasant Viewing erotic pictures _____ Viewing adventure and sport scenes _____ Viewing household objects _____ Viewing food _____ Viewing pictures of people's faces _____ Viewing pictures of accidents, disasters, and waste _____ 9. Which color predicted the possibility of receiving a shock? ________________ 10. Which color predicted that you could not receive a shock? _________________ 11. Please estimate the number of sounds you heard over the headphones during the experiment: ________ 12. Rate how difficult it was for you to keep your eyes focused at the center of the screen while a picture was on the screen: 1 2 3 4 5 6 7 extremely difficult not difficult at all 13. Rate how difficult it was for you to keep your eyes focused at the center of the screen in between viewing pictures: 1 2 3 4 5 6 7 extremely difficult not difficult at all 14. Please estimate the number of pictures you saw during the experiment: ___________ 15. Please rate how sleepy you were at the end of the study: 1 2 3 4 5 6 7 very sleepy not sleepy at all

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66 16. Please rate the percentage of time (%) you found yourself doing the following things: When there were pictures on the screen: (a) Thinking about receiving a shock (when the shock light was on): 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% (b) Thinking about not receiving a shock (when the no-shock light was on): 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% When there were no pictures on the screen: (a) Thinking about receiving a shock (when the shock light was on): 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% (b) Thinking about not receiving a shock (when the no-shock light was on): 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 17. Before you actually received the shock, did you think you would receive a shock during any of the safety periods (when you were instructed that you could not possibly receive a shock)? Yes No If yes, please circle how probable you thought it was: 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 18. Please feel free to add any additional comments or suggestions you might have about the laboratory, the experiment, or your experimenter: _________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

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67 LIST OF REFERENCES Arntz, A., van Eck, M., & Heijmans, M. (1990). Predictions of dental pain: The fear of any expected evil is worse than the evil itself. Behaviour Research and Therapy, 28 , 29-41. Berg, W.K. & Davis, M. (1984). Diazepam blocks fear-enhanced startle elicited electrically from the brainstem. Physiology & Behavior, 32 , 333-336. Boulis, N.M. & Davis, M. (1989). Footshock-induced sensitization of electrically elicited startle reflexes. Behavioral Neuroscience, 103 , 504-508. Bradley, M. (2000). Emotion and motivation. In J.T. Cacioppo , L.G. Tassinary , & G.G. Bernston (Eds.), Handbook of psychophysiology , 2 nd ed., pp. 602-642. Cambridge University Press. Bradley, M.M., Codispoti , M., Cuthbert, B.N., & Lang, P.J. (2001a). Emotion and motivation I: Defensive and appetitive reactions in picture processing. Emotion, 1 , 276-298. Bradley, M.M., Codispoti , M., Sabatinelli, D., & Lang, P.J. (2001b). Emotion and motivation II: Sex differences in picture processing. Emotion, 1 , 300-319. Brown, J.S., Kalish, H.I., & Farber, I.E. (1951). Conditioned fear as revealed by the magnitude of startle response to an auditory stimulus. Journal of Experimental Psychology, 41 , 317-327. Caprara, H.J., Eleaer, P.D., Barfield, R.D., & Chavers, S. (2003). Objective measurement of patient’s dental anxiety by galvanic skin reaction. Journal of Endodontics, 29 , 493-496. Center for the Study of Emotion and Attention (CSEA NIMH). (2001). The international affective picture system: Digitized photographs . Gainesville, FL: University of Florida, The Center for Research in Psychophysiology. Cook, E.W., III. (2001). VPM reference manual . Birmingham, Alabama: Author. Corah, N.L., O’Shea, R.M., & Ayer, W.A. (1985). Dentists’ management of patients’ fear and anxiety. Journal of the American Dental Association, 110 , 734-736.

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68 Dao, T.T. & LeResche, L. (2000). Gender differences in pain. Journal of Orofacial Pain, 14 , 169-184. Davis, M. (1989). Sensitization of the acoustic startle reflex by footshock. Behavioral Neuroscience, 103 , 495-503. Davis, M., Falls, W.A., Campeau, S., & Kim, M. (1993). Fear-potentiated startle: A neural and pharmacological analysis. Behavioural Brain Research, 58 , 175-198. Deane, G.E. (1961). Human heart rate responses during experimentally induced anxiety. Journal of Experimental Psychology, 61 , 489-493. Fanselow, M.S., DeCola, J.P., De Oca, B.M., & Laneira-Fernandez, J. (1995). Ventral and dorsolateral regions of the midbrain periaqueductal gray (PAG) control different stages of defensive behavior: Dorsolateral PAG lesions enhance the defensive freezing produced by massed and intermediate shock. Aggressive Behavior, 21 , 63-77. Fowles, D.C., Christie, M.J., Edelberg, R., Grings, W.W., Lykken, D.T., & Venables, P.H. (1981). Committee report: Publication recommendations for electrodermal measurements. Psychophysiology, 18 , 232-239. Globisch, J., Hamm, A., Schneider, R., & Vaitl, D. (1993). A computer program for scoring reflex eyeblink and electrodermal responses written in Pascal. Psychophysiology, 39 , S30. Graham, F. K. & Clifton, R. K. (1966). Heart-rate change as a component of the orienting response. Psychological Bulletin, 65 , 305-320. Grillon, C., Ameli, R., Foot, M., & Davis, M. (1993a). Fearpotentiated startle: Relationship to the level of state/trait anxiety in healthy subjects. Biological Psychiatry, 33 , 566-574. Grillon, C., Ameli, R., Merikangas, K., Woods, S.W., & Davis, M. (1993b). Measuring the time course of anticipatory anxiety using the fear-potentiated startle reflex. Psychophysiology, 30 , 340-346. Grillon, C., Ameli, R., Woods, S.W., Merikangas, K., & Davis, M. (1991). Fear potentiated startle in humans: Effects of anticipatory anxiety on the acoustic blink reflex. Psychophysiology, 28 , 588-595. Hamm, A., Cuthbert, B., Globisch, J., & Vaitl, D. (1997). Fear and the startle reflex: Blink modulation and autonomic response patterns in animal and mutilation fearful subjects. Psychophysiology, 34 , 97-107.

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69 Hamm, A., Greenwald, M.K., Bradley, M.M., & Lang, P.J. (1993). Emotional learning, hedonic change, and the startle probe. Journal of Abnormal Psychology, 102 , 453-465. Johnsen, B.H., Thayer, J.F., Laberg, J.C., Wormnes, B., Raadal, M., Skaret, E., Kvale, G., & Berg, E. (2003). Attentional and physiological characteristics of patients with dental anxiety. Anxiety Disorders, 17 , 75-87. Kleinknecht, R.A, Klepac, R.K., & Alexander, L.D. (1973). Origins and characteristics of fear of dentistry. Journal of the American Dental Association, 86 , 842-848. Klepac, R.K., Dowling, J., & Hauge, G. (1982). Characteristics of clients seeking therapy for the reduction of dental avoidance: Reactions to pain. Journal of Behavior Therapy and Experimental Psychiatry, 13 , 293-300. Klepac, R.K., McDonald, M., Hauge, G., & Dowling, J. (1980). Reactions to pain among subjects high and low in dental fear. Journal of Behavioral Medicine, 4 , 373-384. Klorman, R., Weerts, T.C., Hastings, J.E., Melamed, B.G., & Lang, P.J. (1974). Psychometric description of some specific-fear questionnaires. Behavioral Therapy, 5 , 401-409. Kopacz, K.M. & Smith, B.D. (1971). Sex differences in skin conductance measures as a function of shock threat. Psychophysiology, 8 , 293-303. Lang, P. J., Bradley, M. M., & Cuthbert, B. N. (1990). Emotion, attention, and the startle reflex. Psychological Review, 97 , 377-395. Lang, P. J., Bradley, M. M., & Cuthbert, B. N. (1997). Motivated attention: Affect, activation, and action. In P.J. Lang, R.F. Simons, & M.T. Balaban (Eds.), Attention and orienting: Sensory and motivational processes (pp. 97-135). Mahawah, NJ: Erlbaum. Lang, P. J., Greenwald, M. K., Bradley, M. M., & Hamm, A. O. (1993). Looking at pictures: Affective, facial, visceral, and behavioral reactions. Psychophysiology, 30 , 261-273. Lautch, H. (1971). Dental phobia. British Journal of Psychiatry, 119 , 151-158. Le Doux, J. E. (1990). Information flow from sensation to emotion: Plasticity in the neural computation of stimulus value. In M. Gabriel & J. Moore (Eds.), Learning and computational neuroscience: Foundations of adaptive networks (pp. 3-52). Cambridge, MA: Bradford Books/MIT Press. Liddell, A. & Locker, D. (1997). Gender and age differences in attitudes to dental pain and dental control. Community Dentistry and Oral Epidemiology, 25 , 314-318.

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70 Lipp, O.V. (2002). Anticipation of a non-aversive reaction-time task facilitates the blink startle reflex. Biological Psychology, 59 , 147-162. Locker, D., Liddell, A., & Shapiro, D. (1999). Diagnostic categories of dental anxiety: A population-based study. Behaviour Research and Therapy, 37 , 25-37. Lundgren, J., Berggren, U., & Carlsson, S.G. (2001). Psychophysiological reactions in dental phobic patients during video stimulation. European Journal of Oral Sciences, 109 , 172-177. Lundgren, J., Berggren, U., & Carlsson, S.G. (2004). Psychophysiological reactions in dental phobic patients with direct vs. indirect fear acquisition. Journal of Behavior Therapy and Experimental Psychiatry, 35 , 3-12. McNeil, D.W., Au, A.R., Zvolensky, M.J., McKee, D.R., Klineberg, I.J., & Ho, C.C.K. (2001). Fear of pain in orofacial pain patients. Pain, 89 , 245-252. McNeil, D.W. & Berryman, M.L. (1989). Components of dental fear in adults? Behaviour Research & Therapy, 27 , 233-236. Milgrom, P., Fiset, L., Melnick, S., & Weinstein, P. (1988). The prevalence and practice management of dental fear in a major U.S. city. Journal of the American Dental Association, 116 , 641-647. Milgrom, P., Vignehsa, H., & Weinstein, P. (1992). Adolescent dental fear and control: Prevalence and theoretical implications. Behaviour Research & Therapy, 30 , 367-373. Nitschke, J.B., Larson, C.L., Smoller, M.J., Navin, S.D., Pederson, A.J.C., Ruffalo, D., Mackiewicz, K.L., Gray, S.M., Victor, E., & Davidson, R.J. (2002). Startle potentiation in aversive anticipation: Evidence for state but not trait effects. Psychophysiology, 39 , 254-258. Rhudy, J.L. & Meagher, M.W. (2000). Fear and anxiety: Divergent effects on human pain thresholds. Pain, 84 , 65-75. Riley, J.L., III, Robinson, M.E., Wise, E.A., Myers, C.D., & Fillingim, R.B. (1998). Sex differences in the perception of noxious experimental stimuli: A meta-analysis. Pain, 74 , 181-187. Sabatinelli, D., Bradley, M.M., & Lang, P.J. (2001). Affective startle modulation in anticipation and perception. Psychophysiology, 38 , 719-722. Skolnick, A.J., & Davidson, R.J. (2002). Affective modulation of eyeblink startle with reward and threat. Psychophysiology, 39 , 835-850.

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71 Spence, K.W. & Runquist, W.N. (1958). Temporal effects of conditioned fear on the eyelid reflex. Journal of Experimental Psychology, 55 , 613-616. Spielberger, C.D. (1983). Manual for the state-trait anxiety inventory . Palo Alto, CA: Consulting Psychologist Press. Sullivan, E.R., Cuthbert, B.N., Karpinia, K., Hefti, A., & Lang, P.J. (1996). Ouch, that hurts! Blood pressure and heart rate responses to a dental exam. Psychophysiology, 33 , S81. ter Horst, G. & de Wit, C.A. (1993). Review of behavioural research in dentistry 19871992: Dental anxiety, dentist-patient relationship, compliance, and dental attendance. International Dental Journal, 43 , 2265-278. Unruh, A.M. (1996). Gender variations in clinical pain experience. Pain, 65 , 123-167. van Wijk, A. J. & Hoogstraten, J. (2003). The Fear of Dental Pain questionnaire: Construction and validity. European Journal of Oral Sciences, 111 , 12-18.

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72 BIOGRAPHICAL SKETCH Tammy Silakowski grew up in Austin, Texas, and received her BS in psychology with a minor in biology in 2001 from Southwest Texas State University. After working as a post-baccalaureate fellow at the National Institutes of Health and a research coordinator for psychiatric clinical trials, she entered the behavioral neuroscience doctoral program at the University of Florida in 2003. Ms. Silakowski has worked as a research assistant at the Center for the Study of Emotion and Attention during her graduate career at the University of Florida. Her research has examined physiological reactivity during pain anticipation. Ms. Silakowski was recently awarded a Student Poster Award by the Society for Psychophysiological Research for the presentation of portions of this research.