Climbing suppression: Passive avoidance in the turtle

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Climbing suppression: Passive avoidance in the turtle 1 IRWIN M. SPIGEL 2 AND KENNETH ELLIS T EMPL E UNIVERS IT Y TABLEI Mean Number of Se conds per Trial for each Shock Group in Five Extinction Trials Group Trial 2 3 4 5 O- volt 200.2 155.8 296.2 436.0 460.0 3D- volt 161..5 279.8 310.6 550.5 288.5 45-volt 360.0 481.1 363.3 414.0 495.6 60- volt 458.7 724.8 380.0 651.7 326.7 90-volt 404.8 321.3 305.1 340.7 348.0 was attained. Five daily 1/2-hr. shock-free extinction trials follwed. Results Functions relating both number of trials to criterion and mean second's of climbing per trial to criterion, to shock level are shown in Fig. 2. One S in the 0 volt (control) group failed to zero out and trials were arbitrarily halted after the 50th day. Analysis of variance across shock intensities are highly significant in the case of both acquisition measures (F=6.9, p< .01; F=19.2. p< .01, respectively; df=4). Although the dif- ference between the O-volt and 30-volt groups is not statistically significant in number of trials to criterion, the difference between these groups with respect to mean second's per trial to criterion is highly significant. With regard to the five extinction trials, neither total climbing time nor mean second's of climbing statisti- cally differentiated the groups . The latter values are given in Table 1. Diseussion Passive avoidance, in the form of a suppression of the turtle's natural response to climb from a walled enclosure, was obtained without difficulty, and shown to vary with shock intensity in a negatively accelerated manner. The persistence of this response is reflected in the high mean second's per trial for Ss in the O-volt MERCURY SWITCH 115 VAC CLOCK 115v RELAY re i CAGE FlOOR CAGE WAll 115 VAC Fig. 1. Abstraet The per si stent effort by the turtl e Cnrys cmys to climb from awalled en closure is utiliz ed in a situation which allows for the study of passive avoidance in this specie s. Aparametric examination of the effects of shock intensity on this behavior produc ed the expe cted gradients for two measures of avoidance acquisition, but fail ed to yield differences in extinction. Problem The ave rsi ve natur e of walled confin ement to turtles of the spec ies ClitYSf III Y S pi c (a has been previously r eport ed by the author in connection with studies of detour lea rning (Spigel, 1964). When confined in such fa shion. Ss a re apt to spend much of their time at- te mpti ng to c limb out of the enclosure. The current e xper iment was de signed to explore the possibility of utili zing this natur al climbing response in the examina- tion of passive avoidance in Chrysc mys. Specifically, the suppress ion of this re sponse as a function of shock inte ns ity wa s inve sti gated with appa ratus in which the S's natural response produc ed the noxious contingency. Subj.·.·.s Twenty male and 10 female Chrys etnys were em- ploye d. Ss were divided se mi- randomly into five groups, the rcs triction being the a ssignment of two females to each. Ss were between 3 and 4 yr. of age as estimated fr om ca ra pace length. \pparutus A circu lar metaboli sm ca ge , 8-1 /2 in high and 8 in in diameter wa s wired into the ci rc uit shown in Fig. 1. A mer cury switch was taped to the forward de cline of the S's cara pace such that when a lie of approximately 20 0 wa s a tta ined, a shock circuit was completed by S bet ween the floor and wire wall of the cage which had been in sul at ed f rom one anothe r. Closing the switch a lso simultaneous ly activated a clock. Both circuits were broken by a r eturn of the S to the horizontal. In this manne r. Ss received shock only while climbing, and a record of total climbing time (and seconds of shock) was obtained. Shoc k level was controlled by a variable tr an sformer . A squ ar e scr een, 14 in ona side and 12 in high surrounded the climbing cage. Flexible wire was used for the mercury switch connection and drawn up- ward through the wir e cover of the c age with sufficient slack to allow complete fre edom of movement for the S. Proeeduri' Five shock intensiti es were employed : 0,30,45,60 , and 90 vo lts AC, one group of Ss exposed to each . Ss wer e given 1/2 hr. s essi ons daily in the apparatus until a crite rion of one full se ssion totally free of climbing Psy ch on Sci. 1965. Vol 3 215

Transcript of Climbing suppression: Passive avoidance in the turtle

Page 1: Climbing suppression: Passive avoidance in the turtle

Climbing suppression: Passive avoidancein the turtle1

IRWIN M. SPIGEL2 AND KENNETH ELLIST EMPL E UNIVERSIT Y

TABLE IMean Number of Seconds per Trial for each Shock Group in

Five E xtinc ti on Trials

Group Trial

2 3 4 5

O- volt 200.2 155.8 296.2 436.0 460.0

3D-volt 161..5 279.8 310.6 550.5 288.545-volt 360.0 481.1 363.3 414.0 495.660-volt 458.7 724.8 380.0 651.7 326.790-volt 404.8 321.3 305.1 340.7 348.0

was attained. Five daily 1/2-hr. shock-free extinctiontrials follwed.

ResultsFunctions relating both number of trials to criterion

and mean second's of climbing per trial to criterion,to shock level are shown in Fig. 2. One S in the 0 volt(control) group failed to zero out and trials werearbitrarily halted after the 50th day. Analysis of varianceacross shock intensities are highly significant in thecase of both acquisition measures (F=6.9, p< .01;F=19.2. p< .01, respectively; df=4). Although the dif­ference between the O-volt and 30-volt groups is notstatistically significant in number of trials to criterion,the difference between these groups with respect tomean second's per trial to criterion is highly significant.

With regard to the five extinction trials, neither totalclimbing time nor mean second's of climbing statisti­cally differentiated the groups. The latter values aregiven in Table 1.

DiseussionPassive avoidance, in the form of a suppression of

the turtle's natural response to climb from a walledenclosure, was obtained without difficulty, and shownto vary with shock intensity in a negatively acceleratedmanner. The persistence of this response is reflectedin the high mean second's per trial for Ss in the O-volt

MERCURYSWITCH(.n~)

115VAC

CLOCK

115vRELAY

reiCAGE

FlOOR ~ARIACCAGEWAll

115 VAC

Fig. 1.

AbstraetThe persi stent effor t by the turtle Cnrys cmys to

cli mb from a walled enclosure is utilized in a situationwhich allows for the study of passive avoidance inthi s sp eci es. A parametric examina tion of the effectsof shock intens ity on this behavior produced the expectedgr adie nts for two measures of avoidan ce ac quis iti on ,but failed to yie ld differences in extinction.

ProblemThe ave rsive nature of walled confinement to turtles

of the species ClitYSf III YS pi c (a ha s been previouslyr eported by the author in connect ion with studies ofdetou r lea rning (Spi ge l , 1964) . When confined in suchfashion. Ss a re apt to spend much of their time a t­te mpti ng to climb out of the enclosure. The currentexper iment was designed to explore the possibility ofutili zing th is natural climbing response in the examina­tion of pa ss ive avoidance in Chrysc mys. Specifically,the suppress ion of th is r esponse as a function of shockinte ns ity was investigat ed with appa ratus in which theS's nat ur al r esponse produced the noxious cont ingency .

Subj.·.·.sTwenty mal e and 10 female Chrys etnys were em­

ploye d . Ss wer e divided se mi- r andomly into five groups,the rcs tr icti on being the a ssignment of two females toeac h. Ss we re be tween 3 and 4 yr. of age as estimatedfr om ca ra pace length .

\pparutusA ci r cu lar metabolism ca ge , 8-1 /2 in high and 8 in in

diameter was wired into the c ircuit shown in Fig. 1. Amercu r y switc h was taped to the forward decline of theS's ca rapace such that when a lie of approximately 200

was attained , a shock circuit was completed by Sbet ween the floor and wire wall of the cage which hadbeen insul at ed from one another. Closing the switcha lso s imult aneous ly ac ti va ted a clock. Both circuits werebroken by a r eturn of the S to the horizontal. In thismann e r. Ss r eceiv ed shock only while climbing, and ar eco rd of total climbing time (and seconds of shock) wasobtained. Shoc k level was controlled by a variabletran sformer. A square sc r een , 14 in ona side and 12 inhigh sur r ounded the climbing cage. Flexible wire wasused for the mercury switch connec tion and drawn up­ward through the wire cover of the cage with sufficientslac k to allow complete freedom of movement for the S.Proeeduri'

Fiv e shock inte ns iti es were employed: 0,30,45,60 ,and 90 volts AC, one group of Ss exposed to each. Sswere given 1/2 hr. sessions daily in the apparatus untila c r ite r ion of one full se ssion totally free of climbing

Psych on Sci. 1965. Vol 3 215

Page 2: Climbing suppression: Passive avoidance in the turtle

z 35 ---- TRIALS TO CRITERION 1050co

OF CLIMBING;c 0-- - -0 SEC:S;: 30 850 ~... ..'" ze 25 650 ...... ...

!'"~ 20 , 450 ...;,... ,, ~... 15 \ 250 &... ,

\...

"" \ ;;z

10 \ 50 ...z 'b...c '"... ":. " 25

''''0--------

30 45 60 90

SHOCK INTENSITY (volts)

F i g. 2. Functions relating two measures of passive avoid anceacqui si tion to shock intensi ty .

group, which is in essence an habituation contro l. OneS in this group never did reach zero and could notcontribute to the extinction data.

Though two measures of acquisition were found tobe sensitive to differential shock level, the five-trialextinction procedure failed to produce differences in

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mean second's of cli mbing. It is pos sible that an extendedseries of exti nction trial s may yie ld differences rel atingto performance during ac quisition.

The need for fur ther study of both extinction per­formance and the use of shock as an aver s ive stimulusfor the turtle is also sugges ted by the fact that O-voltand 30-volt Ss differed with r espect to amount ofclimbing, a s expe cted, but not in number of trial s tocriterion. This findin g may be analogous to the obs erva­tion in operant s ituati ons of reduction in response ratebut not in tot al number of responses when a mildlypunitive s ti mulus is introduced (Skinner , 1938).

In any case, the procedure de scribed appears en­tirely feasible for further study of passive avoidancein a reptile species, and especially us eful for psycho­pharmacological investigation.

ReferencesSpige l , I. M. Detour l earni ng, ret enti on and di srupt i on in the fresh

water turtle . J . compo physio/. Psuch ol ., 1964 , 57 , 108-11 2.Skinn er , B . F . The behavior of organi sms: an experim ental anal-

ysis. New York : Appleton-Century-Crofts , 1938 .NoteI. T hi s resea rc h was supported by Grant No. MH-08679 from t he

USPHS.2. Now at the Uni versi t y of T oronto

Psychon . sct ., 1965, Vol. 3