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3 1.18 1.2l 1.2e
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G 1.48 1.34 1.45
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10 .93 1.00 .82
11 1.10 .23 .15
12 1.85 1.57 1.15
13 .94 1.23 1.23
14 .73 .57 .88
15 1.22 1.09 1.09



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Reinforced Trials and %ean of First Fhree UCS-alone Trials
Following Reinforcement for Croup Cucs

S Difference Score

1 .33
2 -.09
3 .21
4 .20
5 .03
6 .24
7 -.15
8 .14
9 .26
10 -.0O
11 .27
12 -.04
13 .57
14 .23
15 .21

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U^ Li c ('. '3 (N IN O 0 tI DO


Ilitcnel Crawford aorrnw wns torni Octoner 21, 1932, .it

Louisville, Alah.amn. lie artoe.doi public schools at Jacksinville,

lrorida, nnd w:as Rraduzted from Hobert E. Lee Conior Iligh Ccl.ool

in January, 1952.

Mr. uorrow entered the University of rloridn in eptetmber,

1954, after serving three years with tho II. S. Ar:n. lie received

the degree Rachelor of Arts in psychology in January, 19Ot, and

in frbrluary, 196n, enrolled in the graduate school of the Univer-

sitv of rlorida. After ljeinp jiwarde,]c the depree l:ister orf rts

in psychology in .January, 1962, "r. 'orrod continued his training

at the Ilniversity towards the decree Doctor of Philosphyv.

Mitchel Crawford 'borron is currently an Assistant Proftssor

of Psychology at the University or .'nuth FIr.rida. 'le is married

to the former Marifrances Tucker, and is a meabor of Psi Chi nt

the University o I'loriia

This dissertzition was prepared under the direction of the chairman

of the candidate's supervisory comnittct and hao !,een apnrovoue by all

members of that comittcn. It was submitted to the noan of t!e Colle, e

of Arts and Sciences and to the Craduamte Council, and was approved ss

partial fulfillment of the rcqu)irements Cor the de-yreo o.f Doctor of


December 19, 1964

I.' I, L. i v .: rtA r .in.

'c rn, r',r' ,ln te ,ch, ln

Supervisory Cornittee:


4/2.(j i.


Title: Extinction of conditioned inhibition
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00097938/00001
 Material Information
Title: Extinction of conditioned inhibition
Physical Description: vi, 69 leaves : ill. ; 28 cm.
Language: English
Creator: Morrow, Mitchel Crawford, 1932-
Publication Date: 1964
Copyright Date: 1964
Subject: Extinction (Psychology)   ( lcsh )
Inhibition   ( lcsh )
Conditioned response   ( lcsh )
Psychology thesis Ph. D   ( lcsh )
Dissertations, Academic -- Psychology -- UF   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Thesis: Thesis - University of Florida.
Bibliography: Bibliography: leaves 42-44.
Additional Physical Form: Also available on World Wide Web
General Note: Manuscript copy.
General Note: Vita.
 Record Information
Bibliographic ID: UF00097938
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000568360
oclc - 13647536
notis - ACZ5091


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December, 1964


The author wishes to express his appreciation to the

supervisory committee, Drs. Kime], Pennypacker, "lhaw, Bunnell

and fiartlett. Dr. Runnell Irracioiisly agreed to join the committee

when the study was in its final stapes, yet it profited by his

interest and helpful suggestions.

Dr. Kimcel, Chairman of the Com:;ittee, has provided help

and encouragement, copent criticism, and considerable tine and

interest to the stidy, just as he hns done throulihut the author's

graduate training.


AC.LiO'i L rI 'iNrS . . . . . . . .. .. .

LIST C IG . . . . . . . . . . iv

LIST OF TAfL.S . . . . . . . . . . . v


I:TP UCTIO . . . . . . . . I

II. HITilOD . . . . . . . . .. . . . 11

III. I'CSIJLTS . . . . . . . . ... . . 1.

IV. I I;CUSSI . . . . . . . . .. 32

V. SUIM'AY . . . . . . . . . . . I.

IDI.I0.';,1'Y . . . . . . . . . . . 4.

PFrnICES. . . . . . . . . . . . . 45

RIO';PAPIIIAL KETI .. . . . . . . . ... 69


Figurn Pape

1 Averave magnitude of the unconditioned GE;O Juring
reinforcement and on test trial one 17

2 Mean magnitude of the GSR on the first two CS
Adaptation trials 19

3 Mean magnitude of the CSR on UC! Adaptation trials 20

4 'ean nagnitude of GCNf on the second four C?
Adaptation trials 21

5 Mean magnitude of SR on the last two reinforced
trials and on the first three UCS-alone trials
for Croup Cucs 24

6 tean magnitude of fSR on tho two post extinction
test trials 26

7 The relationship between the UCR Difference Score
and the number of extinction trials 28

8 c:n magnitude of the conditioned G';R on first
three extinction trials 30


Tabl I P, -e

1 Pean and Standard Deviation for C.iR Differenco Scores
for rroup ;, [',r. L12 and C3; C6, (12 31

2 Analysis of Variance of UCR 'ifferenco 'cnrIes 47

3 Acquisitinn liCk 'mapnitrrds (lon Ac) for Croupi I3 A4

4 Acquir.itinn LUCR Hagnitudes (loi ac) for Group F.C 49

5 Acquisition UCR Magnitudes (log bc) for group p rl2 5sn

6 Acquisition UCR 'lanitudes (log Ac) for Croup C3 51

7 Acquisitlon IUCR Hagniitudes (loI Ac) for rromip C6 52

A Acqiiisition 11CR IHanlttudes (lo Ace) for Group CI2 53

9 Ac.suiisition UCRn 4anitudes (Inr Ac) for Croup Cu 54

10 UCR HManitudes (log Ac) for all 5s on Test Trinl 1 55

11 Response Hapgnitudes (log Ac) for all Ss on First
Two CS Adaptation Trials 56

12 'osponse "agpnltudes (lor Ac) for Crnup [3, 1r, and
1.2 onl UCS Adaptation Trinls 57

13 Iesponse 'lar'nitiues (log Ac) for Croup C3, C(, CI2,
and Cues on IJCS Adaptation Trials 53

14 Response Magnitudes (log &c) for Grou: rF3 and C3 on
Second Four CS Adaptation Trials 59

15 Response Magnitdles (log Ac) for Croupl F, an.l on
Second Four CS Adaptation Trials 60

16 Srsp;onse 'lagnitudos (log Ac) for Group .11 and C,, nn
Second Fnur C' Adaptation Trials 61

17 l:osponse MagnEitudes (lo] Ac) for i"rou;, Cucs nn
Second Fnor Cr Adaptation Trials 62

LIST OF TABLES (Continued)

Table Pag<

18 Response Magnitudes (log Ac) for Group CuC on First
Three UCS-alone Trials Pollowing R~einforced Trials 63

19 UCIZ Magnitude (log Ac) Difference Scores Between Iean
of Final Two Reinforced Trials and Mean of First Three
UCS-alone Trials Following Roinforcement for Group Cues 64

20 UCR Magnitude (log Ac) Difference Scores Between Mean
of Final Two Reinforced Trials and First Test Trial
for E and C Crouns 65

21 CR Magnitudes (log Ac) for Group FP, E6, Rnd E12 on
First Three CS Extinction Trials 66

22 CR Magnitudes (log Ac) for Croup C3, C6, and C12 on
First Three CS Fxtinction Trials 67

23 CR .Magnitude (log Ac) Difference Scores Between Yean
of Last Three CS Adaptation Trials and Mean of First
Three CS Extinction Trials for E and C Groups 68

Chapter I


During the course of classical conditioning the unconditioned

response (IICP) Crnws gradually smaller. It has beor recognized th.i

rart of this diminution nay ihe duo tn muscular fatirue of tlo respoiid-

ing orcan (Cason, 1937), may involve a cliange in sensory t' -sholdls

(Judd, 195.), ror may hu a relatively permanent reduction (h.ibitu;ationn)

which is distinguished frun tlhe ormer two (Thorpe, 19S(). In addition

to those an associative factor has also ieen assumed to attenuate tihe 'un.

The associative or learned factor was first reported 1,v I'avlov (1927).

die observed that the U1CP suffered nn inhibitory effect in the: presence

of a conditioned stimulus (CO), and a neutral sritulu', after the two

stimuli had been presented together a Punter or times without thc tin-

conditioned stimulus (UCS). Others (lillard, 1'.33; Lufnrt ard Kimhle,

19SS; Spence and Ilunnuist, 19I5), have also reported the nccurrence of

UnR attenuation in the presence of the C9.

It was not until 1961, however, that rimble anJ Cst (1:61) reported

a study specifically Josigned to investigate conditioned diminution of

trh U(CR. Tlhey assumed that part of tle I.Cq
of a conditioned Inhibitory process under the control of the C',. B)

presentir.c the I.CS sometimes with and so-'etimes without the CS, they

found that tlea ntnlitndo of the unconditioned e-ebhlink as, indeed,

attenuated in the presence of the r" during reinforced conditioning

trials, and nlan that the strength of thli conditior.ed inhibitory


process was related to the interstinulus interval in the same way

as is the conditioned excitatory process. Kitmel and Pennypacker

(1962) extended the findings of Kimble and Ost to the classically

conditioned galvanic skin response (G!RS), and, in addition, found

that the strength of the conditioned inhibitory process was a func-

tion of the number of reinforcements, i.e., there was a greater

reduction in the size of the UCRi during acquisition, and a greater

increment in its size on UCS-alone test trials following reinforce-

ment for groups that received a p.roatur number of reinforced trials.

The present study was an attempt to determine whether the con-

ditioned inhibitory process extinguishes (as does the conditioned

excitatory process) as a result of the presentation of CS-only extinc-

tion trials following reinforced trials, and, if so, whether the amount

of extinction is a function of the number of such extinction trials.

Typical extinction of excitatory CRs has been shown to he a function

of the number of extinction trials. The assumption that the conditioned

inhibitory process extinguishes involves, more basically, the assumption

that such a process is present in the first place, so that the exrorieont

was, on the one hand, an attempt to verify the presence of an inhibitory

process under the control of the CS, and, on the other hand, an attempt

to show that the conditioned inhibitory process behaves in extinction

like the conditioned excitatory process. Two groups of subjects ('s)

were given either paired or unpaired CS(liigt)-UCS(shock) acquisition

trials. At the end of acquisition training each of the two groups was

divided into three sub-groups, differentiated by whether they received

either three, six, or 12 CS-only extinction trials. The test deternining

whether extinction of the inhibitory process had occurred required the

presence ct' the IC? (GCC':!), and thus the U(7. "inc. the inhibitory

process is presa mr to be controlled bV the C', its presence too wau

re;ulred on the critical tests. Ience, to provide the a:,iroriate

testing situation, two aired f'-'IC-. trials woro prerse;arc' waiter the

extinction trials.

The uruose of the inpairud c ntrol grouJi was to provide a

situation in which tihe sae- number of C.Ss nnJ I'C's were present Lut,

at the same time, one in which an essential con,!ition for leurnirn

(i.e., te;mporal conti-uity of the stimuli) was not present. In

addition, another control Rroup was run. This lIttcr Broatp; received

the same tr3atmrnt Juring the ac-qulition ,hase of thi exeriment as

the paired acluiition -roun, but Instead of receiving CT-only extinc-

tion trials, it received 12 UC'-alone trials follovirn reinrforceent,

thus providing a test for tl: presence of cornJitioned dliir.ution of

tie UCR in t'i3 ciustoaary tnnner, i.e., as an Incrcment in 11CP nonlitude

on the UiC-nalone trials following reinforcement over that of the final

reinforced trials.

Historical Poview and Related Studies

Returning to "avlov's report of UTC reduction, he attributed the

Jiminntion to the action of Internal inhibition hroupht on by the pair-

ing of a neutral stimulus with a conditioned stimulus, the r.pared

stiiall never being reinforced. Tihe effective CS, when piescn:ed with

the previously neutral stimulus results in a reduction (i.e., in

magnitude) of the conditioned response (CR), "nnd tl-c inhibitory effect

may extend even to the uncnn liticncd refleies themselves" (r. 75).

Pavlnv called the action of the ralred stiEiuli conditionedd inhibition,"

and the previously y neutral stimulus a "conditioned inhibitor."


During the time between Pavlov's reference to the phenomenon and

1961, only anecdotal mention was nade of an nssociative factor produc-

ing UCR diminution. lilpard (1933), in an nyelid conditioning study,

reported that in one ; the UCR to sound was greater when the C! (light)

was absent than when it was present.

Dufort and Kimblo (1958) noted a lar.e increase in UCR magnitude

when the IKCS was presented alone following 20 paired (S-UCS trials.

The unconditioned eyeblink was larger in the former case, i.e., in

the absence of the CS. Aain in 1958, Spence and Runqiuist (1958)

observed that the UCR to an airpuff was smaller (tliou-h not sipnifi-

cntly so) in the presence of a light that had previously been paired

with an electric shock in a forward condition than it was when the

light had been paired with electric shock in a backward paradigrm,

i.e., when the puff was delivered at the time the shock had been

(i.e., 0.5 sec.) but not at 4.5 sec. It appeared that inhibition

may have been conditioned to the CS (lifht) tand tht the inhibition

generalized to other responses.

The last studies to be mentioned in which an associative inhibi-

tion operating on the UCR was apparently demonstrated but in which

it was not being investigated directly were by Calarbos, Sheatz, mnd

Vernier (1956), and ilrnandez-Peon (1955). These workers, after

implantinr electrodes in either the acoustic pathway (Galanibos,

et al.) or the visual cortex (iernandoz-Peon) of cats, noted a reduc-

tion in the electrical response to a tone, and to a lipht, respectively,

in these areas after repeated presentations of these stimuli. Both

researchers presented the stimuli at fairly constant temporal intervals.

They noted that when novel stimuli were presented the response returned to

near its original strength, and thus in their uords "becomes

delialituated." Cavaiglnni, Clanelli, .and ail ntib'no: (1959),

confirredl the results or lHernand :-Pnon. Galna bs anil 'ernanlez-

Peon ioth ascribed the results to an inhihitory nechanism acting

by way of the hrai ,-stem reticilar fnrnation.

As previously noted, the first study specifically Cesirned and

executed to investi2are conditioned diminution ir the urR has done

ly Kimble and Ust (1961.). This Inquiry attempted, first, to Jomoin-

strate the phenomenon rmpirically and, second, to slinh that tle

amount of recovery of the UCR .lhen the C9 was laittod was a func-

tion of the training interstimlluis interval, i.e., tie interval

between the onsets of the CS und UC., Four groups of Ss were given

50 paired presentations of the CS (light) and UCS (air puff) at

intervals of either 25n, 503, 1000, or 2000 msec. After the con-

ditionin, trials each group was given ton 11C;-alone trials. A

comparison of the average UCR nmanitude on the last five condition-

ing trials on which no CR occurred with the averaco UCl imgnituuio

on the first five IJC'-alone trials showed that therr was a signifi-

cant overall increase in average m.anitude of the I1CR on the UC2;-nlone

tri.ils. However, the increase did not favor cne CS-llIC. intervul over

another, tlout.h the trend or the differences was in the expected

direction. In a sub-experi.ent usinr only .s who showed the greatest

UC;R dimiiintion at any interval, cs were Inter presented 40 paired

acquisition trials, ten at cach of the fiour CS-I('W intervals used

in the main experiment. The order of the trials wns random with

the restriction that each interstinuluc interval had to appear twice

i:n each llock of eight trials. The test trials, UCS-alone, were

presented in the sat(e wny as in the main experieent. C'tatlstically

reliable differences within Ss were obtained in this part of the

experiment with the 500 msec. interval producing the greatest

recov ry and the other conditioning intervals falling off in onount

of UCR recovery on each side of this value.

The authors concluded that they had demonstrated an inhibitory

process in addition to the one comonly called adaptation or habitua-

tion, this loarneo inhibition bein' under the control of the CS. Their

basis for this reasonin- was that when the FC was omitted there was a

significant increase in UCR amplitude. Since there was, in addition,

evidence that the amount of inhibition was a function of the inter-

stimulus interval, and that the function was similar to t!.e function

obtained with other excitatory responses (k'fible, 1947; '!cAlllster,

1Q53), they concluded that the inhibition has learned, and thus were

"inclined to call this a conditioned, or associative, irhibition"

(r. 155).

Other possible explanations of the inhibition were considered by

Kimble and Ost: (1) The likelihood that the inhibition was due to

the automatic interaction of reflex rechanisms was rejected because

only a!out one-half of the Ss showed the inhibitory phb'tnomenon, and

one would expect reflex level phenomien to be more tubiquilous, i.e.,

occur in the vast majority of the Ss; (2) The fact that there was a

graJual diminution of the UCR over trials militated a-ainst the con-

tention that the 's were voluntarily rosistin; heirn itade to blink,

for if this were so, one would expect a zore abrupt reduction of the

response; (3) That the inhibition was due to personality variables

was a possibility, but this could rnot be assessed; (4) Finally, the


possibility was entertained that the inhibition resembled Pavlov's

(1927) inhibition of dolay, a forn of internal inhiitinli, whirh

operates to delay the occurrence of the Ck until just before the

occurrence of the IJC. If the last possibility were the case one

would have to assume that the inhibition of delay was operative at

least until t1e p'resi.ntation of the UCS and that it inhibited the

response to it. IL should be noted that this last altornattivo is

itself a learned source of Inhibition and, beinp so, is not in con-

flict with their basic contention.

Kimiel aud rPonyp.icker (1962) Iperformed ;;n experi-.ent desirnicd

to extend the finlinngs of Kinble and Ost to the classically cundltioned

CSHI and to investigate the relationship between the niaher of rein-

forcements anJ the amount of diminution and recovery of the IMLH.

In tl.eir study tree prouns of F-s received either four, eirht, or

16 paired acquisition trials. A 1,000-cps tone was the CS and a 2.(0

ma. electric sl oc was thio iUC3. A delayed conditioning paradig~n as

era;loyed, with the C. Inlsting 1.0 sec. and the UI's 0.1 ser. The two

stimuli terminated together. Fnllowiin the conditionl!ip trials two

UC'-slone trials were presente.

Comparison of the UCR values on the last tun reinforced trials

anld the two IUC-alone trials shro'ed that there was a significant

overall increment of UCR apilitude on the two Ihfr-alrne trials, and

that the number of reinforcements interacted with this increment

significantly, i.e., there was a preater difference with a greater

number of reinforced trials.

Baxter (1964) classically conditioned the GC', usinp both the

trace and delayed conditioning paradi ms with different grou;.s. In


addition, an unpaired control group was employed as in the present

experiment. !o found that the conditioning procedure led to

significantly greater diminution of the UCR than did the pseudo-

conditioning procedure. Comparisons of the UCRs o' the trace and

delayed groups showed that the delayed paradigm led to greater

reduction than the trace conditioning.

In research similar to that beinp presently reported, Grinjs

(1960) and his associates (e.g., Kiamel, 1960) have investigated

what they call a "perceptual disparity" variable operating on the

amplitude of autonomic CHs and UCRs. Cringes suggests that besides

the excitatory CR, which is learned in conditioning experiments,

there may he another CR, a preparatory set for recent of the UCS.

This preparatory set may result in a depression of the amplitude

of the anticipatory excitatory CR and of the UCR. The perceptual

set which develops during conditioning aay be analogous to the

development of an expectancy, an expectancy s-ecifically of the

presentation of the UCS. When the UCS is not presented or when a

new, i.e., novel, stimulus is presented instead of the customary

UCS, it results in a disconfirmation of the expectancy and a

perceptual disparity response, an increase in CR or UCR amplitude

over that which occurs when the UC: is presented.


Assuming that a CS-controlled associative or conditioned inhibi-

tory process, which operates to reduce the strength of the UCR during

reinforced trials, has been demonstrated in previous studies, it was

of interest to further explore the process to determine if it behaves

under similar conditions like the conditioned excitatory process.


In particular, since it has heen demonstrated that the inhibitory

process is influenced liy the interstimulus interval variable and by

the number of reinforcements variable in the same way that the conJi-

tioned excitatory process is affected, it was of interest to determine

whether the conditioned inhibitory process would extinguish upon the

presentation of CS-alone trials. The following s;'eciflc hypotthescs

were IormulateJ:

1. Paired CS-'ICS reinforced trials will lead to a conditioned

inhibitory process which results, when the CS is present, in a

reduction in size of the !ICR.

2. C: extinction trials following reinforcement will produce

extinction of the conditioned inhibitory process.

3. A greater number of C' extinction trials will result in

greater extinction of the conditioned inhibitory process.

4. lCR recovery follcwinp C" extinction trials will occur at a

more rapid rate for groups that received paired acquisition trials

than for groups that received unpaired acquisition trials.

Hypothesis No. I simply asserts that an inhibitory process will

be conditionrJ to the CS, and lIIpotheses los. 2 and 3 state that the

inhibitory process will extinguish, and that the amount of extinction

will be a function of the number of extinction trials, rec:,ectively.

IhTpothesis :o. 4 Ipredicts that there will hl an interaction Iectween

type of training, (paired or unpaired) and numhrr of extir.ction trials

(three, six, or 12). This prediction was based on the assumption that the

paired reinforcement groups will have, early in extinction, two factors

serving to reduce the amplitidle of the UCR on the test trials. The

first factor is the in!iliitinn resulting fro hbnhituntion or adaptation,


and the second factor is the inhibition resulting' front the conditioned

inhibitory process SBt the unpaired reinforcement groups will be

influenced by only the first of thcse factors. Later in extinction,

it is expected that each of those factors, habituation or adaptation,

on the one hand, and conditioned inhibition, on the other, will both

have been dissipated.

Chi-pter II



One hundred and five University of I'lorlrn uLdergradulates serveJ

as volunteer Is. The tcital sample consisted of 63 men and 42 woven.

There were nine men and six wowen in each grouzi, and each 5 recoivred

one dollar for participating.1 The Ss were assigned randnlsly to the

various experimental conditions with the exception of sex lalancing as

noteJ alovo.

l.xnerimentr1l losirn

A two X three factorial design was euprloned in the main part of

the study. The factor with two treatment catreorics was typc of

training; the treatment consisted it whether t:e CS ani. 'JC'; ere

presented paired or unpaired, during reinforce.*riit. The other factor

was the numt.or of extinction trials; the inalivildual treatments were

either three, six, or 1' of such trials. Thus six Jifferent treatrent-

coahinations were generated From such a design; three Croulps (E3, L(,

r.12) lich received paired acquisition trials ~ero differentiateI hvb

receiving either tree, six or 12 extinction trials before tne two

aired test trials, and three rrnuns (C3, r., C]2) which received

unpaired ncauisitinn trials were also diffrer.tiatre in extinction

l s were pnid out of Nil' rrant ('4-00.t0-2) to Dr. it. I. Kimel,
University of Florida.


by whether they received three, six or 12 extinction trials before the

paired test trials.

In addition to the groups discussed above, another group (Cucs)

was run. This group was treated identically to the paired CS-UCS

groups during acquisition. However, instead of receiving 12 extinction

trials with the CS only, it received 12 UCS-alone trials, and then the

two paired test trials. The purpose of running this group was to

provide for the demonstration of the conditioned inhibitory process

in the same way as it has previously been demonstrated, i.e., as an

increment in UCR amplitude occasioned by the omission of the CS.


After ho arrived at the laboratory, the S's left hand was cleaned

with acetone and then he was seated in the ventilated, dirmly lighted

experimental chamber. Next, the shock electrodes were attached to

the fingertips of his right hand and the GS1 electrodes were attached

to the palm and back of his left hand. He was asked if he was com-

fortable, and he was told that the door was to be closed but that he

could speak to the exnerirenter (F.) at any time through the intercom

system. Indicating that the instructions would be read over the

intercom system, E. pointed out the projector which presented the CS,

left the chamber and closed the door. Approximately two minutes later

the instructions were read. They indicated that the experiment dealt

with the effects of certain stimuli on the galvanic skin response,

and that the S should pay attention to these stimuli.2

2The complete instructions appear in Appendix A.


The ; was fir5t given thn presontatlins of the CS alone, followed

by three presentationss of the 0ICS .elono, in intensity increment i;' to

the intensity used during conditlnnin-. This was followed by four

additional presertations of the C' alone. duringg the conditioning

period, which occurred next, three grcups of '; (r3, r., i-12) received

16 paired CT-UCf presentations, and three Froups of Ss (Ci, C6, C12)

receiveJ 16 urnpaireJ C'-lC' l resentatlnns. After the conditioning

trials, ?roup;s r3 and C3 received three CS-only trials, .Lrou:s 1:6 and

C, receiveJ six CS-only trials, an.d groups C., and C12 received 12 Cf.-

only trials. Group rucs received, after 16 paired CS-iC'S presentations,

12 '.CS-alona trials. Followiin tiese trials all rroups received two

paired CS-UC'; test trials.


The 's were seated in an iiidustrial Acoustics Co., Inc. AiJdu-

metric Chamber, Modul No. 1200. The chair in which they sat was a

standard office chair with arrests on which the fs' kept their arms

during the experimental session. The r. could communicate with the

Ss at all times through a two-way Intercom system.

The CS was a circular, white light placed at eye level 30 Icches

directly in front of the S's face. The light wa. produceJ by .

Irason-Stadler Co. '1ttltt:le Stimulus Projector (Type r458G). The

light had a Jiameter of one Inch.

The UICS was an electric shncl delivered throuhli silver-coated

electrodes attached to the middle and index fingertips of the r's

rirlit hand, The shock was produced by a Schultz Instruiments Co.

Constant Current Shock Gienerator. The shock intensity used during

conditioning was 1.5 ma.


The durations of the CS and UCq were controlled electronically by

a Tektronix, Inc. Wavoform Generator, Type 162, and Pulse Cenerator,

Type 161. The CS had a duration of 5.1 sec. and the IFCS a duration

of 0.1 sec. On paired conditioning trials the two stimull terminated

together. The interval soparatinq trials was varied unsystematically

by E within 30-60 sec. Both stimuli were presented within a 30 sec.

interval for the unpaired control groups. These 30 sac. intervals

were separated from each other in the saie way that paired conditioning

trials were separated, i.e., varied unsystematically between 30-60 sec.

On half of the trials the CS occurred first and on half of the trials

the UCS occurred first, except that in no case did more than two

consecutive CSs or UCSs occur. In addition, the next to the last and

the last CS preceded the UCS.3

The CSR was picked up from the palm and back of the S's left hand

by 3/4 in. zinc electrodes, covered with a few drops of zinc sulphate

solution, in lucite cups filled with saline electrode jelly. It was

amplified by a Dio-Physical Research Instruments, Inc. CSR Amplifier,

Model 201-R, and recorded on a Texas Instruments Co. Recti-Riter with

a paper speed of 12 in/ain. All responses were transformed according

to the formula:

1 1
log -~ 109 + 1.0

3The CS was presented first on the last two acquisition trials
because the dependent variable, as noted in the text, was computed
as a Difference Score between those trials and the first test trial.
Following this procedure, the testing conditions were identical for
the paired and unpaired acquisition groups, except for the temporal
separation of the stimuli in the latter group.

where Ph is the resistance at the moment of initlntion of tl.o response

anid i is the resistance at the peak of the response. This log

cniiductancc-chanre unit has leen shown to be the most appropriate

measure for transforming CS Il ata (Iacey annJ Teell, 1949; !a~aJrd,


Chapter III


Diminution of the UCR

Since support of the major hypotheses of the experiment pre-

supposed the presence of conditioned inhibition of tho UCR, it was

first necessary to establish that inhibition of the UCR occurred and

that part of this inhibition was due to a conditioning factor.

The UCR was measured as the maximum decrease in resistance which

occurred between two and five seconds after the offset of the UCS,

and was transformed as previously noted.

Fig. 1 shows the mean magnitude of the [UCR for the combined i

(N=45), combined C (?N45), and Cues (:=15) grouis as a function of

reinforced trials.l Also indicated in Fig. I are the mean UCR wagni-

tudes of the V, C and Cucs groups on the first post extinction test

trial. Discussion of the Ccs group will be presented below.

The figure shows that the mean UCRs of both the F and C groups

diminished as trials increased, that they diminished at about the

same rate, and that the UCRs of the F groups were not smaller than

the UCRs of the C groups except on trials 11 through 14. Since it

was expected that the UCRs of the E groups would show greater diminu-

tion during acquisition than the C groups due to the combined effects

IThe data from which this and all other Firs. were plotted
appear in Appendix B.


Sn a a 0

o o _)

0 9 < I? ',< o

i I \ u -

/ -J

a CD
( > z> -
, I I. -


<0 fl 0 0 L 0
0 0mm. a N
h 0
71 1,

I o L 1 I I i I i n

0 0 cn cn o i -.

(3v E0O-) 3anl]N NvlAI a13n rItIV3


of habituation of the response and a conditioned inhibitory factor,

but that the UCRs of the C groups would diminish only because of

habituation, it may be that there already were proup differences

at the start of the conditioning trials, and that the F groups were

initially more responsive than were the C groups. If this were so,

it would be indicated by the respective groups' responses to the iCS

and CS adaptation trials, prior to conditioning. Figs. 2, 3, and 4,

showing the average responses to the CS and UCS before conditioning,

support the contention that the groups made larrer initial responses

to the UCS and CS than did the C groups. Again, the discussion of the

Cues group, whose data also appear in these fii're,., will be delayed.

In Fig. 2 it can be seen that the E groups produced a larger mean

GSR to the first two adaptation CSs than the C groups, on both presen-

tations of the CS. The overall difference between these two groups was

highly significant (t = 3.54 with 88 df, n <.001). Fig. 3 shows that

the E groups made greater moan GSRs to all three initial UCSs than did

the C groups. The figure slows also that the mean GCR increased over

trials. It will be recalled that the intensity of the UCS was increased

on each trial so that on the final UCS trial the intensity was equal to

that used during reinforced trials. The increasing' intensity of the

UCS during these trials presumably accounts for the fact that the

response became, on the average, larger instead of smaller as it did

on the two sets of CS adaptation trials (with a constant CS). The

overall difference between the mean GSI; magnitudes of the E and C

groups on these trials was also statistically simrficant (t 2.62

with 88 df, p <.02). fig. 4 indicates that the mean CSR to the second

four CS adaptation trials was larger for the E1 groups than it was for

LA 0

0 u

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II \


I, ,\









O l O inO 0n 0 0 0
r- r-. (D in 1 T

(07 901) 3anilN9VLAJ 8SO NV31N

I h

o_ a- D
D =)
O 0


i. o
x -O
\ i

I 0

\ I I Q

\ \ \\ \

0\ 0 0 |000

(OV 9O0) 3GnlIlNgV t$9 NV3h


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0 0 0 0 0 0 0 'n 0
r-. (.0 InO It rn

(0-7 90) 30fiiN9O3VN S9O NV3VA



the C groups although th1e groups were virtually equal on the last

trial. The overall difference between the means of these two

groups also approached significance (t = 1.92 wit! R8 df, p < .10).

In addition to these data, the acquisition performance of the

Cucs group also sig rests that conditioned diminution of the UC!i occurred

because of pairing of the CS and UCS. It will be recalled t!at this

group was treated Identically to the rF roups but, instead of receiv-

ing; CS extinction trials, it received 12 UCS-alone presentations during

the "extinction" phase of the experiment. As rigs. 2, 3, and 4 show, the

Cucs gronu had a Sean GSCR nagnitude intermediate to that of the ? and C

groups on the initial CS and UCS adaptation trials, but showed, us is

indicated in Fig. I, greater atte.uation of the UCPR Jurlng acquisition

than either the I or C groups. In Fig. 1, showing the mean UCRs of the

Cucs grrup on the 16 reinforced trials, there was a rapid drop in magni-

tude on the third trial, after a slight initial increase on the second

trial. Following this there was a slight, more pradual reduction as

trials continued, with a rise toward the end of the trials. These data

further support the contention that the i groups fallen to show a smaller

UCR on the reinforced trials because of their increased responsiveness

at the beginninR of the experiment, i.e., snnplinG differences. It

supports the contention because in this one instance where the hyper-

responsiveness was absent greater UCR diminution was demonstrated.

The Cucs group also permits the Jeionstration of conditioned

inhibition as a difference (i.e., incrmennt) in UCR mragnitude between

the nean UCP on the final two reinforced trials and the mean UCR on tlo

first three LCS-alone trials ia~ediately thereafter. In general, this

is the way in which it was demonstrated in the three previous studies


mentioned love (Ei.ihle aun Ost, 1961; mnnmel ani PennypacLer, 1962;

Baxter, 1964). difference Scores "were compuuted for the rC., Criup

between t:e mean ICR on the f'iral two reinforced trials and the first

three liS-alnne trials. Fig. 5 depicts the differences hetwe.n the

mean UCT's at these two points. It shors that ttcre uns an increase

in the UCR on the first three I'CS-ulone trials over the LICI: rn the

final two reinforced trials. The TeAil of theo "ifferenco cvres was

.155, with the UICR showing a greater value on tle IUC;-alone trials

for all but four Ss. A t test indicateJ t!ht this increase in tihe

IUCi on tile UlCS-alon trials was hiphly significant (t 3.15 with 14

df, p <.OOS). It isouild bh noted spain that the Differenco Scores

cormputed Ifr this rroup were between the final two reinforced trials

and first three iiCS-alone trials. Since the Iroan UCR on the last t-o

reinforced trials happened to he larger than the ICils on any uneiihl:lr-

iny trials after the third, as shnwn in Fir. I, it lend; even reater

confidence in the signifiiunce level referred to above, and, thus, to

its impilicati nns.

rxtinrction of liCR Inhibition

Since th' above data were taken to support the pr.nsu.positinn that

a condiitioned inhibitory phenomenon occurrcd in the prnoups that received

pairdJ Cs-ics trials hilt not in tlose Prouns that received unpaire.i

trials, it was of interest nrxt to test t!:e hypothesis that prrsenta-

tion of the r(; without the LIUC (i.e., an extirction pirnc'LIOre) r.t;ulJ

result in extinction of the inhibition. To evaluate this h.potlheir.,

another l:CR Difference core was crnployel as the dolpender't tariahle.

It was cot;uted by subtractinl th ean ICr rn the fin-.l two reinforced

trials frno the UCIh on the first post-uxtinction p;ired. test trial for


0J- C4

,0 ::

\ 0 0

C 9.4-


\ .d 041

o --

I ,- O

I- c" N

(OV 901) 3anlNsv~J aS9 Nv]iAJ


esch S. Since ;, carefl cop;'arison of thle t11:Rs n the tuo test trials

indicated that relearninZ hnd occurred eniote rapidly, because the lC;t

was considerahlv smaller on the second of the two post-extinction

trials, especially on the part of the r ground, it was decideJ to use

only the response on the first test trial in computinr the differencee

Score described above. Fir. 6 shows the nean UCR magnitudes for tih

E nnd for the C groups as well as for the Cucs ~ group on the two ;ost-

extinction test trials. Ai is indicated, there was a considerable

drop in moan 11CR nagnitudo in the I groups on the second test trial

hut not in the other two grous. Incidentallv, this finding also is

in conformity with the contention th.t a conditioned inhibition occurred

in the r. groups and not in the C groups. (It does not relate to another

such an inriibitioln occurred in the Cues group I.ccause this group dild

not receive CS extincticn trials, did riot extinguish the in!iibitlin,

and thus could not releani the inihibitic.n.)

;t can be seen in riEs. I and 6 that the P group i prodJcedJ a larger

mean UCR on the first post-extinction test trial than did either the C

or the C,,, groups. Indeed, the size of tle average UCR of the I"

groups was comparable to that on the very first reinforced trial, whi;l

the C and Ccs groups showed little If any increment following extinction.

On the contrary, the C1cs grOLIp shoe-d a lower mear II'CR on the post-

extinction test trial than it did on the final two reinforced trials.

The analysis of variance of the LCR Difference Scores indicated that

the greater overall increment in IJCR ma-nitude on theo ost-extiniction

test trial by the E groups in com.parrion to the C groiius was statis-

tically significant (p <.05). Table 1, in ArpenJix II, presents a

suamarv of the Analysis of Variance which evaluated these data. Tho

) D.
W0 0

0 ] ^0

< a)


F- "

0 0

W7 CO -
o o. I 0

(3V 901) 30NllN9VN ?1S9 NV:IIJ

greater increment Ib the r groups when comp.lre,1 to the C groa1lps was

nttributahle solely to the types of training received by the different

prou;'s because they received identical trentment in all other phases

of the experiment.

'umber of extinction Trials

it was of interest next to evaluate the hypothesis that t:.e amount

of extinction of conditioned UCP inhlibition wouldd he a positive function

of the nunlier of extinction trials. Fie. 7 shows the ealn lCR Difference

Score for the I groups that received either three, six, er 12 CS extinc-

tion trials, amid for the C groups that received either three, six, or 12

C, extinction trials. Ne-ative values on the ordin.te indicate that thu

average UCR on the test trial was lower than on the flial two reinforced

trials, and positive values indlic.te that the average UCPC was higher on

the test trial. It appears from tle figure that extinction of the

inhibition was essentially complete hy the their. extinction trial and

that further presentation of extinction trials had little, if any,

effect on the nvorage magnitude of the I:CR on the test trial. Con-

trary to the hypothesis, a -reater nueher or extinction trials did

not lead to greater extir.ctino7 of the conditioned (Ci' inhibition .as

shown by the fact that the F ratio t'fr tie effect of pusher of cx-

tinction trinis lailcd to reach' a significant value. A gin, Table I

in Ap1pendix B surazrizes the Analysis of Vorinnce of t..ese data.


The fourth major experimental hyipothcsis was that tire would be

an interaction between typL of truiring (whetl.er paired or unpaired

CS-I:tC prosontations) and nuaor of C; rxtincticr. trials (whether

threr, six, or 12). This interaction was iredicteI because ir was


U) 0U

c O

0 C

u oa

I o

II -



N-)Z (

N0 - o -
s-)m Q ) *

0 LO O 3a uI_ 0 -I 0 0I
0 0 0

expected that the r gprnups WoulJ lose the Inhibition as well bs the

habituation acquired turint reinforcdaent, but tl-t the C rrou:-s,

since they 'ad not been condJtioned to inhibit the UCk, uoiild lose

only wlint habituation hadt been acquired. Pef'rrin; to lig. 7 at-in,

it can be seen th:.t except for Croup C3 the curves; of tl'e liirferences

Scores are essentially parallel. '.y the C3 Croi-i should. show a nopa-

tivn moan UClH Difference Score value (i.e., why it should produce

smaller average IC1s on the post-extinction test trial) is ont readily

ap;arcnt. An irisportion of the res-onses of the individual ';s in this

frniup Indicatedr that fiir S; were primarily resronsihle for the loier

favcrace 11CR Dirference ccore. Three of the r'for 's did not repo.nd

on the test trial after producing relatively lnrre mean L.CPII on

tho final two reinforced trinls. Analysis of lr risnce r' the Piffer-

enco scores for t:'o interaction effect did not reach szinificarce,

and thus the hypothesis was not surorted. P-efer to T.able I in

Appendix !I for the Analysis of Variance summary.

rxritatnry (I') ConlJitionin"

It was :lso of interest to examine t!o relationship I etwoen tile

type of training nnl C."R nignitudo (ir rcsi-nse to the CS) Jurirv CS

extinction trials. 1his is, of course, the iusial excitatory (CI:)

measure of conditioning, with which nost classical condirtining

stuJies :,re ccncernel. The CR wa.'s easiired -s the emximur Jecrease

in resistance which occurred between three nnd seven seconds after

the onset of tLe C ', nn;d wns transforne,' as previousl' noted.

Pit;. S iindic.tes tile avernge GCin (CR) mannituJe for the colrbied

L and cnlbined C groups on each of the first three C, extinction trial%.

It Is clear that tle F groiuip prn!iiced greater avcrapao Cr's on each of



o0o) 3iQllNNVIN

I In I

dS9 NV31I








tho three L.tinctlior triuls rlthn the C groui;'s. It is .-lsn cleir that

little, if" nny, CH extinction occurreJ on the three trl.1s. CR

Liffercncoe corcs for each S were co.'iutei by ihtracting t!:e lverapF

oaTritude nF Cr,'!' on the anst thicu CiS-nlono presentations -nrior to

crnditioninu from t-e- average na2niltude f r'.r! on the three extinction

trials. TIie iean of tlhe C-' differencee Sc'ors lindrctc.I that the ivecr:re

C-IR of the cE groi;-s increased fron before to after the r'einforcolnt

period, nn.l the avcrage C'R of the C groups 1ecreaocd durir,. the s:\ac

period. TIe difference botr~een the rieans of the fDfference carries was

statistically siriificant Ct = 2.25 with A. 9 O <.-05), .urrnrtinii

thel conclusion, tlhat conventional cxcitntory (1r) conditioning nccurrer.

T.bhle I below shows the reans and stnnardJ dviationr, no tce iffercence

scores for each of tlh I1 and C rroups.

TA31L 1

Ieanr anJ Srtandard Deviation for CR Difference Scores for Croiij L.3, L.
El, and C3, C6 C12

rS 1(,17 C; C., C1

Mean .186 .045 -.Old -. 12< -.055 -.147

.D .290 .033 .27. .120 .34 .176

Chapter IV


Evidence of a Conditioned Inhibitory Process

The results of this study support the hypothesis that an inhibitory

process under the control of the C; developed during reinforced trials,

and that the inhibitory process reduced the magnitude of the UCR.

During reinforced trials the UCR diminished gradually, and when the

UCS was presented alone following reinforcement the size of the IICR

recovered immediately to near its pre-acquisition value. The recovery

of the ICR in this manner was demonstrated with Ss group p Cucs) who re-

ceived paired CS-UCS acquisition trials followed by a series of IJCS-

alone trials.

Other evidence that a conditioned inhibitory process was present

was sunplied by Ss who received paired acquisition trials hut were not

tested for the conditioned inhibitory process in the usual manner.

These Ss showed a greater relative reduction in their CSR1s from, on

the one hand, the CS and UCS adaptation trials to, on the other, the

final few reinforced trials than did groups that received unpaired

acquisition trials. It is assumed, regarding this greater relative

drop by the paired acquisition groups, that the conditioned inhibitory

process acquired during reinforced trials was not great enough to over-

come the initial group differences. As a result, smaller UCRs were not

produced on the reinforced trials. Supporting this argument was the

f.ct that the UC.s of Cropu'- C a a rnoup whons CSlis to the adaptation

trials were Intermediate to those of the F and C groups, were sallor

th.-.n the I!CRs of the C ;roups on every reinforced trial after the second

except two, the eighth and sixteenth. Aii.d, finally, although! the pres-

ence of the usual cnnditioneJ excitatory process did not cup 'ort the

notion that a ccIlditiored iiihibitory princess 6as present in the paired

acquisition groups, it was comfortin to the argument exprcssedr that

excitatory contlitionins was "resent in these groups, and not in the un-

paired acquisition prou.s, since its aesencr weight very well be taken as

harmful to the argument.

The data presented in this .*xpurlaent nre iin accord with the finJ-

inr.s of Kimllea and Ost (1961), Kimel andl Pennypacker (1962), and

Baxter (1064), nnd, toethicr with these stuJies, represent -nother

study in which a conditioned nliihitory process under the control of the

C; has been deimnstrated.

However, the results of these experiments might 1ie viewed Iy some

as showing the effects of "surprise" on the ma.nitiuJe of the UCH. The

argument that the increase in !UCR streoisth on I'CS-alone trials folioan.g

reinforced trinls was the result of the q's surprise at the omission of

the CS is dlfficllt to answer hecnusa it has not boen hyponthesized

unamabiuously Just uhat the effects of a siirrise factor or process are

on Iaohavior in general, let alone the unconditioned CrR in particular.

Green (l95A), however, suvgests th;it surprises" 'iay lie defined in at

least tho uwys. First, it is "roposod only that the term be "defined anJ

mtasorcd in rarts of autenonic respfrTisr's such as the ('R" (p. 340).

Alternatively, it may be related to tihe foresecl.bility of al event

accordin- to a predictionn ade onn an inductivo hasis." (p. 3.10). For


example, a verbal itea preceded by a lon" series of numerical itoas has

more surprise value than the same item preceded by a shorter series.

Green hypothesized that the surprise engendered by such a procedure more

adequately explains the so-called Von "estorff effect. A search of the

literature failed to turn up other suggestcins regarding the effects of

surprise on behavior. However, Kieal and Pennypacker (1962), antici-

pating the "surprise" argument presented above, noted that even though

the S might very well be surprised at the omission of the CS, the

"reduction-of-surprise function" eccruinp to the CS during reinforced

trials is itself an inhibitory function.

In addition, it should be pointed out that in the present study the

unpaired acquisition groups should have, following the second definition

proposed by Green, produced! greater rSRs on the test trial than the

paired acquisition groups since the "foreseeability" of the UCS following

the CS on the test trial had not been increased by the training procedure

as it had for the paired acquisition groups. And because the unpaired

groups could not have foreseen the occurrence of the UCS so presented,

they should have been more surprised and thus should have produced great-

er UCls, assuming that surprise leads to larger autonomic responses such

as the GSR. The data, as has been pointed out, did not confirm this


1 xtinctiCnh or th; Con, it-l ri. d Ilohibitory I'roc.s

The results of the experiment indicate that the paired acquisition

groups produced a significantly greater overall increase in UCR on the

paired test trial following the CS-only extinction trials than did the

unpaired acquisition groups. This finding confirms the hypothesis that

the conditioned inhibitory process extinguishes following unreinforced


presentation of the C'. I'ollowin, the extinction trials the paired

acquisition groups produced UCRs on the test trial similar in magnitiude

to those produced on tlie initial acquisition trials, indicating thit the

inhibitory effects of both the conditioning process nind those of the

adaptation process had teen lost during the CS-onlv presentations.

Tic (ICs of the unpaired acquisition r.roujns on the test trial were,

overall, considerably smaller titan those they produced on the Initial

acquisition trials. Indeed the value of their test trial UCRs uas

strikinrly similar to the average value of the final few acquisition

trials. lTis finding was somewhat unoxnacted in vieu of the fact that

thel adaptation to the lIC.; aciqired during the acquisition trials was

exl-ectoJ to dissipate durin= the C.-only trials. Fig. 7 indicates that

the greatest amount of UCR recovery occurred in Cron'ps C6 and C12, and

Ground C3 resrondCd, on the average, wit:i smaller UCIR on the test trial

thin it did oni the last toh acquisition trials. As mentioned previously,

the reduction of the UCR on tlhe post extinction test trial by Croup C3

war primarily due to the response of four Ss. three or wihom failed to


Iffect of Niumber of rxtinction Trials

Tl.cnuih t!ere uas a p.reater overall recovery of the IfCP on the test

trial ly the promis tliat received paired acquisition trials over that nF

the groups tlh.t received unpaired acquisition trials, the data indicate

that a greater number of extinction trials did not ie:a to .a greter

amount of recovery. Stated in another %ay, the hypothesis ed positive

relationship Ihetween nu.L-,er of extinction trials anA extinction of tile

conditioned inhibitory [rocmess was not confirm udl by the data. Ns Fi... 7

demonstrates, extinction of the conditioned inhibitory process, as


indicated in part by amount of recovery of the P'CR on the test trial,

was virtually complete after the third extinction trial. Further

extinction trials led to only slightly greaterr recovery on the test


It may be that the course of extinction of the conditioned

inhibitory process does not nrogress in the same fashion as does

extinction of the conditioned excitatory process. That is, perhaps

the relationship depicted in Fig. 7 represents the "true" relationship

governing these variables. Reasoning analogically from CR extinction

curves is not especially helpful since so many different curves have

begun observed with that response process. For example, the most

cowonly found curve of extinction of Ci's is essentially negatively

accelerated (Kleitman and Crisler, 1927; liilyard, 1933; Ilovland, 1937;

and others). Other curves have been observed P(ilgard and Marquis,

1935; liovland, 1936), hut perhaTs rpost relevant with regard to the

present experiment is the rapid initial drop in the extinction curve

of CRs reported by Razran (1956), and Spence, (1963). In this latter

curve there is a further gradual diminution of the CR, following the

abrupt drop, very similar to that in the present study. The abrupt

initial drop has been explained as due to generalization decre~snt,

discrimination decrement, automatic deconditioning, loss of motivation

due to the omission of the UCS, and to an inhibitory set resulting from

recognition by the S that the conditions of the experiment have changed

from those in acquisition to those in extinction. It may he that one

of these factors, or a combination of them, in conjunction with a factor

to be discussed below, was responsible for the rapid extinction of the

conditioned inhibitory process indicated by the data. Incidentally,


the factors contribution' to the rdevelo-,'cnt of thr Inhibitory set

could have been respr.isible, in = similar way, for the ra,,id relearning

of the conditioneJ inhibitory process on the, paired test trials follo.-

In extinction by the r. proupps, oxciept that in this ra-c the sot would

have to be virewd as facilitative. 'pcncc, Ilonzir, and RutledIle (1964)

hive sho.,n that when the de-ree of discrininnhility of the procedural

changes that occur -ith shift froi acii isition to extinction is reduced,

thl initial drop in CR strength on the first few extinction trials largely

disappearnr. That facilitative or In'iihitory sets 'ave an effect on a.tuint

of con:ditonnin. has also been dcnonstrateJ in stuJics that have varied

instruction tn '. prior to cnnlitinnin- (':orris an.i Gr:int, 1349; Nicholls

and Fi ble, Q164).

rIelevance to Pavlovian and I illian Theory

An important consiilration in unJrrstniilin2 the extinction of tho

inhibitory process in the present experilmont is the wJv in which it

may interact with tlihe growing exttnctiv- inhibit in resulting from the

CS-only trials, Accrdinp to Pavlov (1327), not only do C'-alono

trials result in the development of internal inlhiition, hut reinforced

trials do also. Indeed, Pavlov viewed the function of reinforcement

after the establishment of the excitatory process as serving principally

to retard or delay the development of Inhibition. Various forms of

inhibition, besides the one reported in the present experiment, obrerveJ

during reinforced trials, include Inhilition of eelay (Pavlov, 1927) and

inhibition of reinforcement (Hlovland, 193f).

Pavlov viewed extinctive inhibition, conditioned in'ihition (a form

of inhibition paradiftatcnally different fro- the subject matter of this

experlimnt), arnd inhibition of delay as being all instances of internal


inhiition. Internal inhibition was a Dore thstract notion, bein-

conceptualized as one of two major cortical processes (the other

was cortical excitation) presumed to mediate overt behavior.

Different C's were all viewed as being instances of the unitary cortical

excitation. Though little work has been directed toward the problem,

it is well known (Kimble, 1961) that other responses than tFe one

recorded and reported by the experimenter are conditioned during rein-

forced trials, and that these other responses may interfere with or

facilitate the response observed.

It is clear that the method used in this experiment, i.e., CS-

only trials, to overcome the conditicneJ inhibitory process was not

the method reconnonded by Pavlov to reduce inhibition. Tnstead,

Iavlov is unequivocal in asserting that such a procedure leads to

the development of inhibition.

It may be that the development of inhibition resulting fro, the

CS-only trials was responsible for the reduction of the inhibitory

process conditioned by the reinforced trials. 6ut since the develop-

rent of extinctive inhibition usually appears to be much slower than

what would have to be the case in the present experiment, perhaps some

other factor was also involved. It should he noted that Lull's (1943)

explanation of extinction, embodying the notions of reactive inhibition

(an inhibition similar to Pavlov's internal inhibition), and conditioned

inhibition (a learned tendency not to respond), likouise has difficulty

handling the present data. The theory implies that extinction will

occur gradually, unlike the abrupt extinction indicated by the present


The Disiiihibition 'lypotiiesis

It is possible that the factor responslhle for the ra.'id loss of

the conditioned inhibitory process is similar to the disruption of

inhthition, i.e., dlisinihihtion, de-onstrited in other studies (I'Fvlov,

1927; !lovlanJ, 1936; tinnick ~iJ [lint, 1951) by tihe introduction cf

novel or extraneous stiluli during extinction. If this is so, it

could be that the change in the stimulus situation occasioned bIv tl.e

omission of the UCr: during thfl cxtinctinn trials was oi' s-ufTicirnt

novelty to produce the disinlibiting effect. :ovlan.l (l 3.') 'xplainedi

tho rise in tie CR extinction curve followin:r '.as-ed practice in a

similar way. He olberved that massing of reinforced trials produced

nn inhilitory effect ihlch resulted in a depression of the CR. i:e

labeled the phenomenon "inhibition of riinforcement," and hypothesized

that the early extinction trials would result in a disruption of this

inhihition. Ilovland concluded from the data that the increase in CR

strcnrth on the first few extinction trials waq due to the disinhibl-

tion of the inhibitiun of reinforcement. If the relatively rnpid

extinction in this study (i.e., only three trials needed to roacn

almost complete UIl:-recovery) was ,Ju to disitliihition, it is not

Isurprising tl.nt further trials had little a!Jditienal influence. This

,possibility, of course, siiuposts immediately an ema;irical test, n. rmly

n experiment on extinction of UCR-Jiminution ini which only one

extinction trial is piven. If the UCR in the Cr-1ufS test trial

following a single extinct, n trial is as Inrre as t1'ea NR carl)

in condlitior.ing, the disinhlibltion exrlrinarinn would be greatly

strong thenel.

Chapter V

The purpose of the present study was to demonstrate the presence of

a conditioned inhibitory process in classical conditioning, and to deter-

mine whether it extinguishes in a manner similar to the extinction of

the conditioned excitatory (CR) process. To do this, two props of Ss

(N=45) were given 16 paired or unpaired CS-UCS (Lipht-shock) acquisition

trials. Following this, each of the two groups was divided into three

sub-groups differentiated by roccivin: either throo, six, or 12 Cr-only

extinction trials. In addition, another group was given paired acquisi-

tion trials, but during the "extinction" phase of the experiment it rec-

eived 12 UCS-alone trials. Following" the extinction trials, each group

received two paired test trials. It was hypothesized that:

1. An inhibitory process under the control of the CS would be

conditioned during classical conditioning trials;

2. The conditioned inhibitory process would extinguish during

C-only extinction trials;

3. The amount of extinction of the conditioned inhibitory process

would be a positive function of the number of CS-only extinc-

tion trials;

4. Croups which received paired acquisition trials would show a

more rapid rate of recovery of the UCR on the test trials thnn

p.roups which received unpaired acquisition trials.

The results of the experiment supported, albeit indirectly, the hypo-

thesis that a conditioned inhibitory process occurred in the r groups, and


not in the C rro:ps. InJircct evidence .aF roauireJ because the UCR.

of the P groups became only slightly smaller than those of the C crotup

during rrinforceiwnt.

Analysis of variance of I'ifference Scores hctwecn the I'CVn of tile

first test trial and tl-e final t,.; acquisition trials indicated that

tlero was a sinlific;anrly greater overall recovery of the 'JCR on tlh

test trial by the I rrou:'s than hy the C groiiis. This finding, lends

support to the hypothesis that the conditinnel inlibitorv process

extinruishes on presentation of C'-only trials. I'owever, the analysis

diJ not support the third and fourth hylpotheses.

The failure of the numbor of extinction trials variable to he

positively related to 'he amount of extinction was interpreted in rela-

tion to Pavlov's internal Inhibition concept. In addition, it 3as pointeJ

out that iprha3fs Srence's notion o" the JlevulorIrent of an inhibitory set

during early extinction trials could possibly account for tie abrupt

extinction. Alternatively, it was suggested that the findlnrs could have

Ieon die to disinhibition of the conditioned uithlbitory process.


Baxter, R. Conditioned diminution of the unconditioned response.
thUublished doctor's dissertation, University of Florida, 1964.

Cason, H. The organic nature of fatigue. Aner. 1. Psychol., 1037,
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Cavapgioni, A., Gianelli, G., 6 Santibanez, E'. r. Effects of repe-
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liilgard, C. R., & Marquis, D. C. Acquisition, extinction, and reten-
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!lilgard, r.. I., C '4arquis, '. C. C(ndJticnit and lear.lnp.
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.lovlind, C. I. "Inhiblition tI' reinforceaont" and pheno.nenn of ex;,cri-
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linvland, C. I. The generalization of conditioned responses. III.
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Pull, '. I.. Princlnles of Behavior. New York: Arpleton-Crntury-Crofts,

.ludd, P. i. I'nsic correlates of the visual stvl ilus. In 5. S. Stevens
(id.) handbook of xrerrimental Psvcholonv. New York: 'l lcy, 1951.

Kimabl, ';. A. Coiiditionina as a furictioi of the tire between cor.ditinned
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l:ir.hle, C. A. Iilgard and ':lrqiis' Coiiditionin! and I.earnin.. ::ew York:
A'pletlon-Century'-JCrn'ts, Inc., 1'61.

Kimble, C. A., C DGuort, R. II. ThiC aRsoci:tive factor in eyelid con-
ditionin-. .1. exr. .sychol., 1956, 52, 3P6-3n1.

Kmable, r. A., :'ani, L. 1., 6 Dufort, R. II. Classical and initrimental
eyelid conditioning. .7. cx. oPsychnl., 1'15S, 4Q, 407-417.

:iUble, C. A., 5 fst, 1. W. '. conditioned iihabi:ory prr'cess in
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inmeol, II. P. The rnlatinnship ibetacen direction and onrount of stirulus
ch.inpe .nd arnunt of norcoptual disparity re~"ons .. .. ep. Psvehnl.,
1960, SO, 68-72.

immeel, I. P., F Pennyracler, H. S. Conrditined diminution of the uncon-
dltioited response a-' a function of the inirber of reiinorceamets.
J. ex!'. Psycehol., 1962, 64, 2C-23.

Kloitmrn, t'., Crisler, C. A qigntitative study of a salivary condi-
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Lacey, ". I.., 5 Siegel, P. 1. An analysis lf' the unit of ecafurement
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?FcAllistor, K. y. Tyclid conditioning as n function of the C!'-UI:S
interval. J. exp. Psychol., 1.13), 45, 417-422.

:iicholls, t. r., i'ible, G. A. Irfect of instructions upon eyelid
conditloninR. J. exp. Psvchol., 1964, 67, 400-402.

Norris, F. B. r Crant, D. A. Eyelid conditioning as affected by verbally
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Oxford Univesity 'ress, 1-27.

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Spence, K. W. (Lecture presented at University on Florida, April, 1963.)

Spence, K. W., 4 RLunquist, i '. Ten,;poal effects of conditioned fear on
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Spence, K. W., llomzie, !i. J., f rutledpe, E. F. Extinction of the human
eyelid CR as a function of the discriminability of the change from
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Winnicl, W. A., F Hlunt, .. IcV. The effect of an extra sti-ulus upon
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'sychol., 1951, 41, 205-215.




This is an experiment on the effects of certain types of stimuli

upon the galvanic skin response. Your task is very simple: all you

rust do is stay awake and pay attention to the stimuli. Please

remain motionless throughout the experiment.

AI'Pr.:I x B


T'A' Ll 2

Analysis or Variance of I'Cr Itifferonce scores

Source d F

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