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Positive and negative conditioning of the GSR
Acta Psychologica 21 (1963) 100--107; © North.,.~oiland Publishing Co. Not to be reproduced by photoprint or mica'ofilm without written permission from the publisher
POSITIVE AND NEGATIVE CONDITIONING OF THE GSR
S. H. LOVIBOND
Department oJ Psychology, University oJ Adelaide
The discovery in the !imbic system of both positive and negative reinforcement areas (6, 2) has led to renewed iaterest in the respective roles of aversive and appetitive stimuli in the control of behaviour. For example, Meeh! (5) has recently proposed a theory of schizophrenia which assumes the possibility of significant intra-individual differences in the efficiency of the positive and negative re~aforcement systems. Meehrs theory would pre,~ct for example, that comparative studies of positive (appetitive) and negative (aversive) conditioning in human Ss should revea~ important factors of conditionability which are specific to the two types of response system. On the other hand, thec:nes such as that of Eysenck (3) which postulate relationships between conditio'aiag and personality varifi01es, assume a strong general factor ~f conai,~ionability. Measures of conditioning have usually not been found to coT~:~late ~ghly, but Eysenck (4) ha-., argued that the procedures used to date do not permit an. adequate test of the general factor hypothesis. Eysenck has emphasiTed the sources of variability associated with peripheral response m~.chanisms. F,xamples of these sources of variability are ~he number of ,.,wear glands in the palm for GSR conditioning, and ~he sensitivity of the cornea when the eyeblink is conditioned. ~ e puq~ose of the e.xperiment 1:obe described was to compare human conditionin!: under conditions of positive and negative reinforcement with the variable of peripheral mechanism controlled by the use of a single respo.~Lsesystem; the galvaaic skin retlex. METHDD
General
Each 5 attended two GSR conditioning sessions 2--7 days apart. In one session electric shock served as the UCS. In the other session coloured slides of nude females provided the reinforcement. 100
POSITIVE AND NEGATIVE CONDITIONING OF THE GSR
101
Subjects Sixty~five male students of Psychology in the University of Adelaide, with an age range of 1 8 ~ 2 6 years, served as -~ubjects.
Apparatus The circuit used to measure the GSR was that described by Davis, Siddons and Stout (1) modified to drive a Both pen recc, rder. The degree of attenuation employed varied from S to S between 1(3~0and 200 ohms per mm of pen deflection. The S's palm was rubbed thoroughly with electrode jelly before attaching the electrodes, which were placed as far apart as practicable on the palm of the left hand. The 50-cycle AC electric shock was produced by a constant: current electr~nic stimulator and was dehvered to the tips of the second and fourth fingers. The nude female slides were projected in stereoscopic pairs through polaroid filters by means of twin Paximat 35 ~nm projectors with automatic slide changers. When viewing the :dide~ S~s wore spectacles with appropriate polaroid lenses. The stimuli to be condi~.~oned (C$) and ~Lfferentiated (DS) were tones and lights. In one sessic~v the CS was a 500 cycle tone and the DS was a 1500 cycle tone. '!hese tones were generated by two audio-oscillators and fed th:rough earphones at approxim'.~teiy 60 db above threshold. In the other session the CS was z. red light and the DS was a white light. 'The light stimldi were provided by two 32 V, 15 W lamps mounted side by side in a box and arranged to iUuminate two circular ground glass apcrtures 3 in. in diameter and 9 in. apart in the front panel of the box. The entire seqt~ence of stim,J~us events was presented automatically by a :~ystem of elec!ronic timers and switching apparatus. The task ~ff the experimenter, onc,.• the session was under way, was simply to monitor the ~.,,,K recorde~ and make any neeessaa3, adjustments to tiie attenuationr and. reset switches. Two adjacent rooms served as the experimented and control rooms. All apparatus ~.as housed in the control room vnd S sat in ar,~ arm-chair 8 feet from a 6' )< 6' metallic screen on which the slides were shown and in front of which the ligh~ box was p~aced. Projection was throu~i~h holes cut in the one-way v isi09n glass which separated the two rooms. The hum of the rec.order and a ventilating fan served to ma~k slight sounds from the control room and outside sources~
Procedure The method of delayed conditionklg was used to provide a measure
102
S.H. LOVIBOlqD
of the response to tihe CS and the DS on every trial. The interval between CS onset and UCS onset was 11 seconds. The duration of the shock was one second and CS and shock offset were simultaneous. The duration of the nude pictures was 10 seconds and in the case of this conditioning procedure the CS and UCS overlapped by one second. The CS and DS were presented in strict alternation with an invariant inter-trial inter~al, measured from CS onset to CS onset, of 55 seconds. Strict alternation rather than random alternation was used to facilitate the development of a "dynamic stereotype" (7). In the preliminary adaptation period, the CS and the DS were each pre~nted twice without reinforcement. The fifth stbnulus was the first reinforced presentation of the CS and it was followed by 11 further CS-UCS combinations alternated with 12 unreinforced DS presentations. During aversive conditioning the DS was presented alone, but during non-aversive conditioning the DS was followed by ~;lides of outdoor scenery. A different nude was presented on each occasion following the CS. The st=ength of the shock was set at 1.5 ma. for the first two shocks and it was then increased to 2 ma. for the remaining 10 reinforced trials. S's post experimental descriptions of the strength of the shock ranged from mild to rather severe. Type of CS and order of conditioning were cotai~e~ balanced. To s u m m a : i ~ the procedure, stimuli 1---4 we re adaptation trials, odd number trials from 5 ~ 2 7 (i.e. 12 in all) were reinforced presentafi~Snq of the CS. Even numbered trials from 6 ~ 2 8 were unreir~forced presentations of the DS. SCORrNa
Unconditioned Responses For the.' parpose of comparing levels of unconditioned respome with the two techniques, ~wo m~.asures were computed for each S in each conditioning situation. 7:['he~e were the sum of the responses to the third and fourth and to the elewmth and twelfth presentations of the UCS. The two measures were termed UCR1 and UCR2 respectively. When no CR or a small CR occurred, measurement of the UCR presented no difficulqr. V~aen, howe~er, a sizable CR occurred, it tended to mask the UCR. Hence a UCR was dofined as the difference in conductance measures obtained at CS onset and at the point of maximum deflection of the 1 ~ which occur:red w'thin five seconds of UCS onset. The unk of conduc~nce change was the square roc, t of micromhos X 100.
POSITIVE AND NEGATIVE CONDITIONING OF THE GSR
]03
Condin'omng Measures The criterion of a CIR was the difference in conductance measures obtained e.t C$ onset and at the point of maximum deflection of the pen during the 12 seconds of CS presentation. If no increase in conductance beyond the !evel at CS onset occurred while the CS was on, the CR was scored zero. The unit of conductance change was the square root cf micromhos X 100. In order to compare positive and negative conditioning performance, a total CR score was computed for each S in each of the two conditioning situations. Total CR was defined as the sum of the GSRs to the ]!~st eleven presentatiens of the CS. RESULTS
Conditioning Curves Fig. 1 presents a comparison of the positive and negative c~nditioning curves.
N tMb ,I.,.
N
Ii.
g~0Slll~ c s - 7 / \ \ ,~/
'%
U,|
Cb
0
• .~
|
i
,
l
1
$
~
S 6 7 $ C $ - UCS PAIRING
9
10
I!
12
Fig. 1. Curves of respo~a~; to the CS and DS in positive ar, J negative conditioning. (C in nfieromhos).
The amplitude of response to the CS is consistently higher with the nega, ve procedure. Differentiation takes a similar course with the two methods, but: the forms of the conditioning curves differ radically. In negative c~nditioning the amplitude of response is close to its maximum afte~ tlie 'first :reinforcement, but the positive conditioning curve is similar in forr~ to the usual type of learo.~ng curve. -
,I.i
104.
S.H. LOVIBOND
Uncom~itioned Responses "]the mean UCRIt score was 13.9 for positive conditioning and 20.9 for negative conditioning. The respective UCR2 scores were 12.8 and 14.7. Tl~e produ,ct moment correlation between the two sets of UCR1 ~ores was + 0.23. The correlation between the UCR2 scores was + 0.21.
Reliability o] CRs The corrected odd-e,~en split-half -~eliability coefficient f6r rt~sponse the 12 presentations of the CS was + 0.94 for positive conditioning and + 0.92 for negative conditioning'
Extent ol Conditioning The difference between total response to the CS and total response to the DS over the last eleven tdalst gave a t test probability of less than .01 in the ease of Ix~th eonditior3ng methods. The number of Ss whr~se total response to CS was not appreciably h i ~ e r than that to DS was four with negative conditioning and 14 with positive conditioning.
Relationship between Conditio~dng Measures ~ e product moment correlation l~e~.ween the total CR scores obtai:~ed from the two conditioning methods was -I-0.36. DIscussioN
Comparison of, Conditioning Curves Perhaps the most striking of the present findings is the difference between the shapes of t~he two conditioning curves. It seems likely that this difference; results in part from different degrees of augmentation of the ori~aal unconditioned response to the (28. Typically:, during the adaptation period, the; initial GSR to the CS declines. When the UCS is shcck, the first reh~'orcement has the effect of disinhibiting this adaptat-.on, the UCR to t/he CS often being augmen~ted beyond its pre~ adaptation level. Thus the high amplitude response to the next CS presentation after the first reinforcement cannot be ascribed to cond i a l o g alone. In fact, Stewart, Stern, Winokur and Fre,dmea~ (8) have a r ~ l ~ rec~ntly that the total increase m response to the CS followk~g the ~ t reinforcen~nt can be, accoanted for in terms of augmentation t ~ UCR to the CS. Therefore, these authors propose as a criterion
POS1T~VE AND NEGATIVE CONDITIONING OIF THE GSR
105
of condJtionJing that the CR should have a latency o~atside the range of latencies c~f unc,anditioned GSRs: 'They' show that CR's defined in this way have all acquisition curve similar ~o the ordinary learning curve. However, s~ch a criterion of conditioning is redundant ff a DS is employed. In ~ i s case the criterion of conditioning is the difference in level of re'sponge to the C$ and the DS. Inspection of the negative concfition~ag cu~'e in fig. 1 reveals ~hat the response to stimulus 7 (the next CS presentation after the ~ s t reinforcemen0 is considerably higher than the response to stimulus 6 (the ne×t DS presentation after the first reinfor~:ement). Tiffs different,: is signi~eant beyond the one per cent level (t : 3.3) and must be ;~scri~d to C~3-UCS pairing, or, in other words~ to conditioning. In the c~se of positive conditioning there is no such difference between the resl:xmses to stimtdi 6 and 7, and hence there is ao evidence of conditioning occurring as a result of one CS-UCS pairit~g. In terms of the present analysis, the high amplitude GSR to the 'first CS following reinforcement includes a large component of unconditioned reaction (due parlly to disinhibition of adaptation and partly to a further augmentation of the reaction by aversive stimulation) and a smaller component of conditioning. With repeated presentations of the CS, the unconditioned cot~ponent becomes adapted, and its cont~ibu~:ion to the observed amplitude of response decreases. At the same ~ a e , the conditioning component increases in the negatively a,~elerated fashion usual in learnnig. A further component of inhibition with reinforcement may operate to depress the observed level of resI~,nse in the later stages of conditioning. The resultant curve may thus rise or decline from the initial starting point, depending on the strength of the, various components. The :,;trength of each component is in tmn probabl~' dependent on such conditions as strength of UCS, CS-UCS integral and inter-trial interval, a!l of which may be manipulated experimentally. In the case of positive conditioning, the initial UCR component is rellatively small, and little conditioning occurs in the first few trials, with the result that a normal learning curve is observed. It would, of couse, be necessary to equate UCS strenght before it could be concluded ~ a t positive and negative methods per se. produce different types of conditioning curves. ,¢
General Factor ol Conditionability _Tl~e circumstances of the experiment appear to be uousually favourable for the demonstration of a general factor of conditionability. In the
10~
S. H. L O V ~ O N D
first placee the specie peripheral factors mentioned by Eysenck (4) as likely to reduce the correlations between conditio~g measures have ~ t l cont~lled by using the same response measure (GSR) in both con&'tioning situations. Secondly, both procedures have bee~ shown to ha~e high split-half reliab~ty coefficients. On the other hand it would be ~mreasonable to expect the more relevant test-retest reliability cc,effieients to be higher than + 0.8. With retiabilities of this order, t~e e~:peeted correlation between two pure measures of a general conditionability factor would be + 0.64. Under these eircun~stances, the relatively 1o~, correlation of + 0.36 which was obtained between po~_iti_ve and negative conditioning measures is not inconsistent with the hypothesis of a general factor of conditionabflity. Nevertheless this result suggests quite strongly that, as required by Meehl's theory (5) there is a considerable degree of specificity in the functioning of the positive and negative reinforcemen| areas. Further evidence on this question might weird ~ sought by cealparative studies of posilive, negative and neutral conditioning which attempt to equate UCo strength. Practical Considerations
There is room for further development o!~ the positive GSR cetlditioning procrdure described here. In pal~icular it ~vould be of advantage to i,lcrease the strength of the UCS ia order ~o reduce the proportion of Ss not conditioning. This could pc.,.sibly be~ ~Lchie~,ed by im:luding the variable of mcwement in the stimulus material. If a ch~ematograph film were used, short moving U(~ S sequences could be separated by neutral or blank film to give the required inter-trial interval. If auditory stimuli were included on the soun,d try,ok, to serve as the CS avid DS, the need for complex external timing ~:ircuits would be obviated. Tile possibilities of producing a standardized film along these lines are at present being investigated. Str~M~Y A compsrisolt of GSR conditioning with positive rei~forcement (nude female p i ~ r e s ) and negative rei~orcement (electric shock) is undertaken using male Ss. i ~ re,suits are not inconsistent with the theory of a general factor oil condi~onabitity, they suggest quite strongly that l~ere is a considerable ~:gree of ~ecificiey in the functioning of the positive and negative reinforcement
POSITIVE AND NEGATIVE CON DI'IIONING OF THE GSR
107
REFERENCES
1. D~vis, R. C., ~i',iddons, G. F. and Stout, G. L., Apparatus for recording auto:aomic states and changes. Amer. L Psychol. 19~4, 67, 343-352. 2. D~lgado, J. M. R., Raberts, W. Wo and Miller, N. E., Learning motivated by electrical ~fimulation of the brain. Amer. J. Physiol. 1954, 179, 587-593. 3. Eysonck, H. J., The dynamics of anxiety and hysteria. London: Routledge & Kegan Paul, 1957. 4. , Experiments in personality. London: Routledge & Kegan Paul, 196(I. 5. Meehl, P. E., ~k'|dzotaxia, schizotopy, schizophrenia. American ;~ychologist. 1962,. 17, 827-838. 4. Olds, J. and Milner, P., Positive reinforcement produced by electrical stimulation of septal area and other regions of rat brain. J. comp. physiol. Psychol. 1954, 47, 419-427. 7. Pavlov, I. P., Conditioned Reflexes, Lc~ndon: Oxford University Press, 1927. 80 Stewart, M. A., Stern, J. A., WinokuL E. and Fredman, S., An analysis of G,SR conditioning. Psychol. Rev. 1961, 68, 60-67.
POSITIVE AND NEGATIVE CONDITIONING OF THE GSR
S. H. LOVIBOND
Department oJ Psychology, University oJ Adelaide
The discovery in the !imbic system of both positive and negative reinforcement areas (6, 2) has led to renewed iaterest in the respective roles of aversive and appetitive stimuli in the control of behaviour. For example, Meeh! (5) has recently proposed a theory of schizophrenia which assumes the possibility of significant intra-individual differences in the efficiency of the positive and negative re~aforcement systems. Meehrs theory would pre,~ct for example, that comparative studies of positive (appetitive) and negative (aversive) conditioning in human Ss should revea~ important factors of conditionability which are specific to the two types of response system. On the other hand, thec:nes such as that of Eysenck (3) which postulate relationships between conditio'aiag and personality varifi01es, assume a strong general factor ~f conai,~ionability. Measures of conditioning have usually not been found to coT~:~late ~ghly, but Eysenck (4) ha-., argued that the procedures used to date do not permit an. adequate test of the general factor hypothesis. Eysenck has emphasiTed the sources of variability associated with peripheral response m~.chanisms. F,xamples of these sources of variability are ~he number of ,.,wear glands in the palm for GSR conditioning, and ~he sensitivity of the cornea when the eyeblink is conditioned. ~ e puq~ose of the e.xperiment 1:obe described was to compare human conditionin!: under conditions of positive and negative reinforcement with the variable of peripheral mechanism controlled by the use of a single respo.~Lsesystem; the galvaaic skin retlex. METHDD
General
Each 5 attended two GSR conditioning sessions 2--7 days apart. In one session electric shock served as the UCS. In the other session coloured slides of nude females provided the reinforcement. 100
POSITIVE AND NEGATIVE CONDITIONING OF THE GSR
101
Subjects Sixty~five male students of Psychology in the University of Adelaide, with an age range of 1 8 ~ 2 6 years, served as -~ubjects.
Apparatus The circuit used to measure the GSR was that described by Davis, Siddons and Stout (1) modified to drive a Both pen recc, rder. The degree of attenuation employed varied from S to S between 1(3~0and 200 ohms per mm of pen deflection. The S's palm was rubbed thoroughly with electrode jelly before attaching the electrodes, which were placed as far apart as practicable on the palm of the left hand. The 50-cycle AC electric shock was produced by a constant: current electr~nic stimulator and was dehvered to the tips of the second and fourth fingers. The nude female slides were projected in stereoscopic pairs through polaroid filters by means of twin Paximat 35 ~nm projectors with automatic slide changers. When viewing the :dide~ S~s wore spectacles with appropriate polaroid lenses. The stimuli to be condi~.~oned (C$) and ~Lfferentiated (DS) were tones and lights. In one sessic~v the CS was a 500 cycle tone and the DS was a 1500 cycle tone. '!hese tones were generated by two audio-oscillators and fed th:rough earphones at approxim'.~teiy 60 db above threshold. In the other session the CS was z. red light and the DS was a white light. 'The light stimldi were provided by two 32 V, 15 W lamps mounted side by side in a box and arranged to iUuminate two circular ground glass apcrtures 3 in. in diameter and 9 in. apart in the front panel of the box. The entire seqt~ence of stim,J~us events was presented automatically by a :~ystem of elec!ronic timers and switching apparatus. The task ~ff the experimenter, onc,.• the session was under way, was simply to monitor the ~.,,,K recorde~ and make any neeessaa3, adjustments to tiie attenuationr and. reset switches. Two adjacent rooms served as the experimented and control rooms. All apparatus ~.as housed in the control room vnd S sat in ar,~ arm-chair 8 feet from a 6' )< 6' metallic screen on which the slides were shown and in front of which the ligh~ box was p~aced. Projection was throu~i~h holes cut in the one-way v isi09n glass which separated the two rooms. The hum of the rec.order and a ventilating fan served to ma~k slight sounds from the control room and outside sources~
Procedure The method of delayed conditionklg was used to provide a measure
102
S.H. LOVIBOlqD
of the response to tihe CS and the DS on every trial. The interval between CS onset and UCS onset was 11 seconds. The duration of the shock was one second and CS and shock offset were simultaneous. The duration of the nude pictures was 10 seconds and in the case of this conditioning procedure the CS and UCS overlapped by one second. The CS and DS were presented in strict alternation with an invariant inter-trial inter~al, measured from CS onset to CS onset, of 55 seconds. Strict alternation rather than random alternation was used to facilitate the development of a "dynamic stereotype" (7). In the preliminary adaptation period, the CS and the DS were each pre~nted twice without reinforcement. The fifth stbnulus was the first reinforced presentation of the CS and it was followed by 11 further CS-UCS combinations alternated with 12 unreinforced DS presentations. During aversive conditioning the DS was presented alone, but during non-aversive conditioning the DS was followed by ~;lides of outdoor scenery. A different nude was presented on each occasion following the CS. The st=ength of the shock was set at 1.5 ma. for the first two shocks and it was then increased to 2 ma. for the remaining 10 reinforced trials. S's post experimental descriptions of the strength of the shock ranged from mild to rather severe. Type of CS and order of conditioning were cotai~e~ balanced. To s u m m a : i ~ the procedure, stimuli 1---4 we re adaptation trials, odd number trials from 5 ~ 2 7 (i.e. 12 in all) were reinforced presentafi~Snq of the CS. Even numbered trials from 6 ~ 2 8 were unreir~forced presentations of the DS. SCORrNa
Unconditioned Responses For the.' parpose of comparing levels of unconditioned respome with the two techniques, ~wo m~.asures were computed for each S in each conditioning situation. 7:['he~e were the sum of the responses to the third and fourth and to the elewmth and twelfth presentations of the UCS. The two measures were termed UCR1 and UCR2 respectively. When no CR or a small CR occurred, measurement of the UCR presented no difficulqr. V~aen, howe~er, a sizable CR occurred, it tended to mask the UCR. Hence a UCR was dofined as the difference in conductance measures obtained at CS onset and at the point of maximum deflection of the 1 ~ which occur:red w'thin five seconds of UCS onset. The unk of conduc~nce change was the square roc, t of micromhos X 100.
POSITIVE AND NEGATIVE CONDITIONING OF THE GSR
]03
Condin'omng Measures The criterion of a CIR was the difference in conductance measures obtained e.t C$ onset and at the point of maximum deflection of the pen during the 12 seconds of CS presentation. If no increase in conductance beyond the !evel at CS onset occurred while the CS was on, the CR was scored zero. The unit of conductance change was the square root cf micromhos X 100. In order to compare positive and negative conditioning performance, a total CR score was computed for each S in each of the two conditioning situations. Total CR was defined as the sum of the GSRs to the ]!~st eleven presentatiens of the CS. RESULTS
Conditioning Curves Fig. 1 presents a comparison of the positive and negative c~nditioning curves.
N tMb ,I.,.
N
Ii.
g~0Slll~ c s - 7 / \ \ ,~/
'%
U,|
Cb
0
• .~
|
i
,
l
1
$
~
S 6 7 $ C $ - UCS PAIRING
9
10
I!
12
Fig. 1. Curves of respo~a~; to the CS and DS in positive ar, J negative conditioning. (C in nfieromhos).
The amplitude of response to the CS is consistently higher with the nega, ve procedure. Differentiation takes a similar course with the two methods, but: the forms of the conditioning curves differ radically. In negative c~nditioning the amplitude of response is close to its maximum afte~ tlie 'first :reinforcement, but the positive conditioning curve is similar in forr~ to the usual type of learo.~ng curve. -
,I.i
104.
S.H. LOVIBOND
Uncom~itioned Responses "]the mean UCRIt score was 13.9 for positive conditioning and 20.9 for negative conditioning. The respective UCR2 scores were 12.8 and 14.7. Tl~e produ,ct moment correlation between the two sets of UCR1 ~ores was + 0.23. The correlation between the UCR2 scores was + 0.21.
Reliability o] CRs The corrected odd-e,~en split-half -~eliability coefficient f6r rt~sponse the 12 presentations of the CS was + 0.94 for positive conditioning and + 0.92 for negative conditioning'
Extent ol Conditioning The difference between total response to the CS and total response to the DS over the last eleven tdalst gave a t test probability of less than .01 in the ease of Ix~th eonditior3ng methods. The number of Ss whr~se total response to CS was not appreciably h i ~ e r than that to DS was four with negative conditioning and 14 with positive conditioning.
Relationship between Conditio~dng Measures ~ e product moment correlation l~e~.ween the total CR scores obtai:~ed from the two conditioning methods was -I-0.36. DIscussioN
Comparison of, Conditioning Curves Perhaps the most striking of the present findings is the difference between the shapes of t~he two conditioning curves. It seems likely that this difference; results in part from different degrees of augmentation of the ori~aal unconditioned response to the (28. Typically:, during the adaptation period, the; initial GSR to the CS declines. When the UCS is shcck, the first reh~'orcement has the effect of disinhibiting this adaptat-.on, the UCR to t/he CS often being augmen~ted beyond its pre~ adaptation level. Thus the high amplitude response to the next CS presentation after the first reinforcement cannot be ascribed to cond i a l o g alone. In fact, Stewart, Stern, Winokur and Fre,dmea~ (8) have a r ~ l ~ rec~ntly that the total increase m response to the CS followk~g the ~ t reinforcen~nt can be, accoanted for in terms of augmentation t ~ UCR to the CS. Therefore, these authors propose as a criterion
POS1T~VE AND NEGATIVE CONDITIONING OIF THE GSR
105
of condJtionJing that the CR should have a latency o~atside the range of latencies c~f unc,anditioned GSRs: 'They' show that CR's defined in this way have all acquisition curve similar ~o the ordinary learning curve. However, s~ch a criterion of conditioning is redundant ff a DS is employed. In ~ i s case the criterion of conditioning is the difference in level of re'sponge to the C$ and the DS. Inspection of the negative concfition~ag cu~'e in fig. 1 reveals ~hat the response to stimulus 7 (the next CS presentation after the ~ s t reinforcemen0 is considerably higher than the response to stimulus 6 (the ne×t DS presentation after the first reinfor~:ement). Tiffs different,: is signi~eant beyond the one per cent level (t : 3.3) and must be ;~scri~d to C~3-UCS pairing, or, in other words~ to conditioning. In the c~se of positive conditioning there is no such difference between the resl:xmses to stimtdi 6 and 7, and hence there is ao evidence of conditioning occurring as a result of one CS-UCS pairit~g. In terms of the present analysis, the high amplitude GSR to the 'first CS following reinforcement includes a large component of unconditioned reaction (due parlly to disinhibition of adaptation and partly to a further augmentation of the reaction by aversive stimulation) and a smaller component of conditioning. With repeated presentations of the CS, the unconditioned cot~ponent becomes adapted, and its cont~ibu~:ion to the observed amplitude of response decreases. At the same ~ a e , the conditioning component increases in the negatively a,~elerated fashion usual in learnnig. A further component of inhibition with reinforcement may operate to depress the observed level of resI~,nse in the later stages of conditioning. The resultant curve may thus rise or decline from the initial starting point, depending on the strength of the, various components. The :,;trength of each component is in tmn probabl~' dependent on such conditions as strength of UCS, CS-UCS integral and inter-trial interval, a!l of which may be manipulated experimentally. In the case of positive conditioning, the initial UCR component is rellatively small, and little conditioning occurs in the first few trials, with the result that a normal learning curve is observed. It would, of couse, be necessary to equate UCS strenght before it could be concluded ~ a t positive and negative methods per se. produce different types of conditioning curves. ,¢
General Factor ol Conditionability _Tl~e circumstances of the experiment appear to be uousually favourable for the demonstration of a general factor of conditionability. In the
10~
S. H. L O V ~ O N D
first placee the specie peripheral factors mentioned by Eysenck (4) as likely to reduce the correlations between conditio~g measures have ~ t l cont~lled by using the same response measure (GSR) in both con&'tioning situations. Secondly, both procedures have bee~ shown to ha~e high split-half reliab~ty coefficients. On the other hand it would be ~mreasonable to expect the more relevant test-retest reliability cc,effieients to be higher than + 0.8. With retiabilities of this order, t~e e~:peeted correlation between two pure measures of a general conditionability factor would be + 0.64. Under these eircun~stances, the relatively 1o~, correlation of + 0.36 which was obtained between po~_iti_ve and negative conditioning measures is not inconsistent with the hypothesis of a general factor of conditionabflity. Nevertheless this result suggests quite strongly that, as required by Meehl's theory (5) there is a considerable degree of specificity in the functioning of the positive and negative reinforcemen| areas. Further evidence on this question might weird ~ sought by cealparative studies of posilive, negative and neutral conditioning which attempt to equate UCo strength. Practical Considerations
There is room for further development o!~ the positive GSR cetlditioning procrdure described here. In pal~icular it ~vould be of advantage to i,lcrease the strength of the UCS ia order ~o reduce the proportion of Ss not conditioning. This could pc.,.sibly be~ ~Lchie~,ed by im:luding the variable of mcwement in the stimulus material. If a ch~ematograph film were used, short moving U(~ S sequences could be separated by neutral or blank film to give the required inter-trial interval. If auditory stimuli were included on the soun,d try,ok, to serve as the CS avid DS, the need for complex external timing ~:ircuits would be obviated. Tile possibilities of producing a standardized film along these lines are at present being investigated. Str~M~Y A compsrisolt of GSR conditioning with positive rei~forcement (nude female p i ~ r e s ) and negative rei~orcement (electric shock) is undertaken using male Ss. i ~ re,suits are not inconsistent with the theory of a general factor oil condi~onabitity, they suggest quite strongly that l~ere is a considerable ~:gree of ~ecificiey in the functioning of the positive and negative reinforcement
POSITIVE AND NEGATIVE CON DI'IIONING OF THE GSR
107
REFERENCES
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