[1962] Recruitment, Latency, Magnitude, And Amplitude of the GSR as a Function of Inter Stimulus...

8/3/2019 [1962] Recruitment, Latency, Magnitude, And Amplitude of the GSR as a Function of Inter Stimulus Interval

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Journal o f Experimental Psychology1962, Vol. 64, No. 5, 513-518

R E C R U I T M E N T , L A T E N C Y , M A G N I T U D E , A N DA M P L I T U D E OF THE GSR AS A F U N C T I O NOF I N T E R S T I M U L U S I N T E R V A L 1

W I L L I A M F. P R O K A S Y , J A M E S T . FAWCETT 2 AND J O H N F. H A L LPennsylvania State University

White and Schlosberg (1952) andMoeller (1954) report that, within theranges of 0 and 5 sec., the op t i mumin ters t imulus interval (ISI) in GSRcondi t ioning is approximate ly .5 sec.when magnitude of response is em-ployed as the dependent variable.Bierbaum (1955), in contrast, reportsa greater response magnitude near3 sec.Whi le it is not clear why his ISIfunct ion should diverge from that ob-tained by White and Schlosberg(1952) and Moeller (1954), Bierbaum(1955) reports, in addi t ion, that re-cruitment ( t ime elapsing between theonset of a GSR and its m a x i m u m )increases with increases in the ISI.Unpubl ished data from our laboratorysuggest, fur the r , that both GSRlatency and r ec ru i tment modify acrossextinction trials.It is the purpose of the presentstudy (a) to examine fur ther GSRcondi t ioning as a func t ion of ISI and( b ) to relate th e independent variable( ISI) to three GSR attributes otherthan m agni tude : latency, recruitment,and ampl i tude . The dist inction be-tween magnitude and ampl i tude firstwas made by Humphreys (1943) andmore recently was discussed by Hil-1 This s tudy w as supported by an NSFg r a n t (G-7463) to the senior author.The authors gratefully acknow ledge the aidof Herbert Krauss an d Barry Lively fo r their

aid in t ransform ing the data to log con-ductance uni ts , and of the staff at the com-puter center of Pennsylvania State Universityfor making the IBM 650 available to us.2 Now with th e Peace Corps, W ashin gto n,D. C.

gard (1951, p. 528) . These authorsemployed the word magnitude to referto a mean based upon all trials, includ-in g those which resulted in no measur-able response, while they adopted theword amplitude to refer to meansderived only from those trials onwhich a response occurred.METHOD

Subjects.The 5s were 129 men andwomen enrolled in introductory psychologywho volunteered with th e knowledge thatshock would be employed. Of these, 23 werelost due to eq uipm ent malfunct ion, adapta-t ion to shock, or E's error,Apparatus.The GSR was measured bymeans of the Fels dermohmeter . The record-ing electrodes were .75-in. zinc electrodes setat the base of Plexiglas cup s of ,125-in. depth .A zinc oxide electrode paste filled the cups andmade contact with S. T he cups were placedapproximately 1 in. apart (center to center)on S's left pa lm wi th a constant current ofTO^a. tran sm itted between them . Resistancechanges were recorded on an Esterline-Angusmill iammeter operating at a paper speed of24 in. per min.The CS, a 76-db. (re .0002 dynes/cm 2)1000-cps tone, was presented by means of aGrason-Stadler twin oscillator throug h Permo-flux PDR-8 earphones, and was superimposedon a constant background of white noisegenerated through the earphones at 52 db.The UCS was a shock administered by an acvariac through .5-in. copper electrodes tapedto 5's right index finger. CS and UCSdura t ion were controlled through Hunter-Brown interval timers.Procedure.The 5s were assigned, ran-domly, to one of five t reatment condi t ions :

0-, .5-, 1-, 3-, or 5-sec. ISI. CS du ration s forthe five cond itions , respectively, were: .2, .5,1, 3, and 5 sec. UCS du ratio n was .2 sec. andbegan with th e termination of the CS in allexcept Group 0, in which the CS and U CSoverlapped.513


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S14 W . F. PROKASY, J. T. FAWCETT, AND J. F. H A L LThe S was seated in a sound-shielded room(6 X 10 X 6.S ft.) which was i l luminated by a

7 5 - w . incandescent bulb. After affixing GSRand shock electrodes, E indicated that shockwould be administered in increasing am ounts,beginning with a barely perceptible level,unt i l it reached a level which 5 judged to be"highly annoying, but not painful ." Themean voltage achieved was 58.7 (SD = 14.5).The S w as then instructed that he wouldreceive either the already experienced shockto the finger, a tone through the earphones,or both, but that there was no necessaryrelationship between the two events. Theearphones were positioned and E returned toth e outer chamber to initiate training trials.All 5s received 20 CS-UCS pairings followedby 10 test (extinction) trials. The intertrialinterval was varied unsystematically between25 and 35 sec. Final Na in each group were:Group 0, 20; Group .5, 22; Group 1, 22;Group 3, 2 0 ; and Group 5, 22.Response measures.The measure em-ployed on each test trial w as the log ofconductance change, as measured from th ebase at CS onset to the point of ma x i mu mpen deflection following any response initia-tion that occurred between 1 and 5.5 sec.after CS onset. To log conductance changewas added a constant of 9, thu s m akin g allscores positive with a range of from .549to 3. (Only 3 Ss yielded scores below 1,and then on only several trials each.) In theevent that the pen deflection failed to meet th ecriterion of a response, a score of zero wasrecorded. The m inim um deflection recorded(as measured by a specially constructedtemplate) was 25, 50, 100, 250, or 500 ohm s,depending upon the dermohmeter sensitivitysetting required to adjust appropriately to theextent of S's UCR durin g shock adjustment.Both magnitude and ampli tude wererecorded as the mean of log conductancechange plus 9 on Test Trial 1 and on each ofthree blocks of three of the subsequent ninetest trials. Magni tude w as obtained by in-cluding the score of zero on trials in which noresponse occurred. The amp li tude index didno t include scores of zero. Fo r example, ifS's scores on Test Trials 2, 3, and 4 were2 . 5 , 0, and 1.1, mean magnitude for thosetrials would be 1.2 while mean ampl i tudewould be 1.8.Latency was defined as the time elapsingbetween CS onset and the occurrence of thefirst response in the criterion range, whilerecruitment was defined as the am ount oftime elapsing between response initiation andresponse peak. The un its of our templatewere in ,03-in. increments which, in conjunc-

FIG. 1. Ampl i tude an d magnitudeas a function of ISI, measured on TestTrial 1.tion with th e paper speed of 24 in. per min. ,permit ted t ime measurement to the nearest75 msec.

RESULTSFirst extinction trial.Responses onthe first extinction trial were em-ployed as the most direct index of theinfluence of the ISI variable, as sub-

sequent responses necessarily reflectedth e added operation of UCS omission.Mean magni tude and ampl i tude as afunction of ISI are shown in Fig. 1.Ampli tude means , based only uponthose 5s who responded, are obtainedfrom Ns of 17, 22, 22 , 16, and 17 forGroups 0, .5, 1, 3, and S, respectively.Magnitude is greatest at .5 sec.and declines with longer ISI intervals,the decrease over ISI values of .5 to 5sec. being significant at the .05 level

TABLE 1L A T E N C Y AND R E C R U I T M E N T MEANS AND SDs

O N TEST TRIAL 1 AS A F U N C T I O N OF ISI

0.5135

1722221617

Latency (Sec.)

Mean2.482 . 5 52.583.112 . 7 6

SD.79.48.901 . 2 2.98

Recru i tment(Sec.)Mean2.503.142.933.232 . 8 7

SD.721.04.90.961 . 8 2


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GSR AS A F U N C T I O N OF I N T E R S T I M U L U S I N T E R V A L 515TABLE 2

MEAN L A T E N C Y , R E C R U I T M E N T , A M P L I T U D E , A N D M A G N I T U D E O V E R THREE B L O C K SO F THREE TEST TRIALS AS A F U N C T I O N OF IS I

ISI(Sec.)

0.5135

N

919181718

Ampl i tudeTrial Block

12.4572.S062.4512.4092.402

22.3842.3752.4002.3052.367

32 . 5 8 12.3432 . 3 9 12.4042.290

Magni tudeTrial Block

12.2852.4592 . 4 1 52 . 2 0 12.374

21 . 8 5 42 . 1 9 72.2232.0852.230

32.4592 . 1 3 62.2031 . 9 2 62.096

Latency (Sec.)Trial Block

12 . 5 32.482 . 4 73.172.89

22 . 5 82 . 5 42 . 5 83 . 3 12 . 9 5

32 . 5 22 . 4 92 . 7 53 . 3 23 . 4 1

Recru i tment (Sec.)Trial Block

12 . 0 52 . 1 52 . 6 13 . 2 32 . 9 3

22 . 0 62 . 0 92 . 3 92 . 8 43 . 0 0

32 . 0 62 . 1 22 . 3 63 . 0 22 . 7 3

Note.Within-cell SDs varied f rom .18 to .50 fo r a m p l i t u de , f rom .24 to .80 fo r magni tude , from .27 to 1.14 fo rlatency, an d f rom .44 to 1.21 for recruitment.(f =3.98, d/= 3/82, error MS =.593).A similar analysis of amplitude didnot result in significant differencesCF=1 .57 , df=3/13, error MS = .119).Table 1 summarizes latency andrecruitment data on Test Trial 1.Fo r neither recruitment (F 1.1,d f = 4/90, error MS = 1.273) norlatency (F = 1.37, df = 4/90, errorMS = .775) were the differencesamong groups significant, although itcan be noted that the longest latenciesoccurred in Groups 3 and 5.Final nine extinction trials.Dataof all 5s who responded at least oncein each of three blocks of three ex -t inct ion trials were employed in theanalyses of variance of the four

response measures. Table 2 sum-marizes the means for all groups whileTable 3 provides a summary of theanalyses of variance. Significant be-tween-groups effects were obtainedonly with the recruitment and latencymeasures, in both instances a largertime value being associated withlonger ISIs. The significant between-5s effect obtained with all measuresattests to their reliability.Both magnitude and latencychanged across test trial blocks, withmagni tude decreasing and latency in -creasing. There was a tendency forampl i t ude to decrease, suggesting thatthere was some decrease in the size of aresponse provided that one occurred.

T A BL E 3A N A L Y S E S O F V A R I A N C E O F M A G N I T U D E , A M P L I T U D E , L A T E N C Y , A N D R E C R U I T M E N TA S A F U N C T I O N OF ISI O V E R THREE B L O C K S OF THREE TEST TRIALS EACH

Between 5sIS IError (b )Within 5sTrialsISI X TrialsError (w )

r i f

8047628152

Ampli tudeMS

. 0 8 0. 2 1 6

. 1 4 3. 0 5 6.056

F

.373.86***2 . 5 61 . 0 0

MagnitudeMS

.572

.7521.716.056.156

F

.764.82***11.00***.36

LatencyMS

6 . 0 6 1. 6 6 8. 9 3 5. 2 6 4. 2 5 9

F

9.06***2.58***3 . 6 1 *1 . 0 2

Recru i tmentMS

8.8791 . 2 8 5.521. 2 0 4.352

F

6.91***3.65***1.48.58

*P < .05.**f < . 0 0 1 .


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516 W. F. P R O K A SY , J. T. FAWCETT, AND J. F. H A L LTABLE 4

M A G N I T U D E MEANS AND SDs FOR ALL 5s AS A FUNCTION OF ISI O V E RTHREE B L O C K S OF THREE TEST TRIALS EACH

ISI(Sec.)

0.5135

N

2022222022

Test Trial Block1

Mean1.4112.2602.1831.9262.007

SD.95.58.72.89.93

2

M ean1.0301.9601.9311.8921.92S

SD.98.81.92.92.84

3

Mean1.1161.8451.9151.6371.715

SD1.11.95.81.98.99

In the above analyses Group 0 hadonly 9 5s that met the criterion of atleast one response in each block ofthree test trials. Because of possiblebias that might enter by such selectionof 5s, a second analysis of magnitude,incorporating data from all 5s, wasmade. Table 4 provides the meansand SD s while Table 5 summarizesth e analysis of variance.Table 5 reveals, first, that there is asignificant between-groups effect and,second, that response reliability (asevidenced by the sharply increased Fvalue for between-5s means) has in-creased. An examination of meanmagni tude in Table 4 indicates thatth e bulk of the differences betweengroups rests in Group 0 ; that is, theincrease in N in Group 0 over th e

prior analysis added sufficient n u m -TABLE 5

A N A L Y S I S O F V A R I A N C E O F M A G N I T U D E F O RALL 5s AS A FUNCTION OF ISI AND THREEBLOCKS OF THREE TEST TRIALS EACHSource

Between 5sISIError (b )Within 5sTrialsISI X TrialsError (w )

d f10541012122820 2

MS

7.5022.0222.343.1792.03

F

3.71**9.96***11.54***.88

bers of zeros to provide a . between-groups effect.Double responses.Although pre-ceding analyses were based on thefirst GSR occurring in the intervalfrom 1 to 5.5 sec. after CS onset, therewere, in Groups 3 and 5, frequentinstances of a second response with alatency range of from 4 to 8.5 sec.after CS onset. Figure 2, a tracingof one such response from an 5 inGroup 5, illustrates the onset of thefirst response, a plateau, and then theonset of the second response. InGroup 5, of 20 5s who responded, 19gave at least one double response.In Group 3, of 18 5s who responded,15 gave at least one double response.With the exception of 1 5 on one trialin Group 0, no double responses wereobserved in Groups 0, .5, and 1.

\f 5 S E C O N D J

**P


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GSR AS A F U N C T I O N OF I N T E R S T I M U L U S I N T E R V A L 517DISCUSSION

T he ISI funct ion obtained w ith mag -nitude as the dependent variable issimilar to that obtained by W h i t e andSchlosberg (1952) and Moeller (1954).Wi th in th e range tested, resul ts of allthree studies suggest that ma gni tude isgreatest near an ISI of .5 sec., sim ila rto the opt imum value obtained inn u m e r o u s studies of skeletal responsecondit ioning (see Kimble, 1961, pp.156 f. ) . That a mpl i t ude did not vary as afunct ion of ISI suggests that the mag-n i tude funct ion is de te rmined in largepart by whe the r or not 5s in the differentISI condit ions responded.3 On thi s basis,th e dis t inc t ion be tween magni tude anda m p l i t u d e ma de by H umphre ys (1 9 43)and Hilgard (1951) merits f u r t he r con-siderat ion.Two of the three observations onla tency and rec rui tm ent have someprecedent in the l i t e ra tu re : the positiverelat ionship be tween ISI and rec rui tmen tcorroborates Bierbaum's (1955) f indingand the increase in latency across ex-t inct ion trials is consistent with Pavlov's(1927, p. 49) report that the latency ofsalivation increases during extinctiontrials. W e have been unable to find aprecedent for the positive relationshipbetween la tency and ISI in a u tonomiccondi t ioning , though such a re la t ionshiphas been obtained with condit ionedskeletal responses (e .g . , Boneau, 1958;

3 Ratios of num ber of responders to numberin each group on Test Trial 1 were IT/20,22/22 , 16/20, and 17 /22 fo r , respectively,Groups 0, .5, 1, 3, and 5 . While there is uoentirely adequate statistical test availableto compare these frequencies for the fivegroups simultaneously, a Fisher exact testcomparing f requency of responders in Group.5 with tha t of G r o u p 3 and of Group 5yielded P values of, respective ly, .043 an d .032for frequency disparities as large as thoseobta ined. Fur therm ore , employing the ob-tained order of mean ma g n i t u d e (from highto low) in the five groups as a basis fo rcomparison, of the 120 possible ways that th eratios could be ordered only 5 would cor-respond as well as or better to the magni tudeorder tha n that obtain ed, even if the tiedratio between Groups .5 and 1 were countedas a reversal.

Ebel, 1961). Th oug h data are l imi ted,present evidence suggests that, in addi-tion to ma gni tude , th e very form of theGSR can be brought under th e control ofexternal stimulating events. Such apossibili ty warrants the continued ob-servation of latency and re c ru i tme n t inGSR research.Few references have been m ade tosecond responses in GSR studies. Rod-nick (1937), with ISIs of 17 and 21 sec.,found that a second response wouldoccur shortly before shock onset, andStewart , S te rn , W inoku r , and Fredman(1961) demonstrated th e acquisition of asecond G SR whi le employing an ISI of7.5 sec. Grings, Lo ckh art, and Dameron(1961) have shown, fu r t h e r , that thissecond response is differentiated morerapidly than is the first response in adiscriminat ion learning situation in whichan ISI of 5 sec. is employed. While th ena ture of the second response is notunders tood, it t ends to occur prior toU C S onset. W h e t h e r or not its absencef rom Gro ups 0 , .5, and 1 results becauseit does not occur in these groups orbecause recording speed is too slow toseparate response rate changes super-imposed on the first response remains tobe investigated.

SUMMARYFive groups of 5s t rained at CS-UCSintervals of 0, .5, 1, 3, or 5 sec. were emp loyedin a s tudy of the role of the interst imulusinterval (ISI) in the co nditioning of the GSR.

All 5s received 20 tone-shock pairings followedby 10 tone alone (test) trials. Fou r attributesof the GSR were mea sured: am pl i tude ,magni tude, la tency, and r ec ru i tmen t .The principal findings were: (a ) magni tudewas greatest with an ISI of .5 ; (b ) magnitude,but not ampl i tude , varied with I S I ; (c) la -tency and recrui tment both increased as afunction of ISI; (d) latency increased acrossextinct ion t r ials; an d ( e ) a second responsewas observed f requent ly in .9s exposed toISIs of 3 and 5 sec.R E F E R E N C E S

B I E R B A U M , W. B. Temporal aspects in con-ditioning of the GSR. Un published doc-toral dissertation, University of Florida,1955.


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518 W . F. PROKASY, J. T. FAWCETT, AND J. F. H A L LBONEAU, C. A. The in te r s t imulus intervaland the latancy of the conditioned eyelid1 response. /.exp. Psychol., 1958, 56, 464-'471.EBEL, H. C. Stable-state behavior andreversibility as a function of the inter-stimulus interval variable in classical eyelidcondi t ioning. Unpubl ished master's thesis,Pennsylvania State Universi ty, 1961.GRINGS, W . W., LOCKHART, R. A., & D A M -ERON, L. E. In te r s t imulus in te rva l as avariable in GSR condi t ioning of m ental lydeficient individuals . Paper read atAmerican Psychological Association, NewYork, 1961.HILGARD, E. R. M e t hods and procedures in

the s tudy of learning. In S. S. Stevens(Ed.), Handbook of experimental psychology.New York: W iley, 1951.HUMPHREYS, L. G. Measures of st rength ofconditioned eyelid responses. J. gen.Psychol., 1943, 29, 101-111.

KIMBLE, G. A. Hilgard an d Marquis'conditioning and learning. (2nd. ed.) NewYork: Appleton-Century-Crofts , 1961.MOELLER, G. The CS-UCS interval in GSR

condi t ioning. /. exp. Psychol., 1954, 48,162-166.PAVLOV, I. Conditioned reflexes. New Yor k :Oxford Univer . Press, 1927.RODNICK, E. H. Characteristics of delayedand trace-conditioned responses. /. exp.Psychol., 1937, 20, 409-425.STEWART, M . A ., STERN, J. A ., WINOKUR,G., & F R E D M A N , S. An analysis of GSRconditioning. Psychol. Rev., 1961, 68, 60-67 .WHITE, C. T., & SCHLOSBERG, H, Degree ofconditioning of the GSR as a funct ion of the

period of delay. /.exp. Psychol., 1952, 43,357-362.(Received October 30. 1961)

[1962] Recruitment, Latency, Magnitude, And Amplitude of the GSR as a Function of Inter Stimulus...

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