The Journal of General Psychology
ISSN: 0022-1309 (Print) 1940-0888 (Online) Journal homepage: http://www.tandfonline.com/loi/vgen20
Stimulus Compounding in Classical Fear Conditioning Melvin L. Goldstein To cite this article: Melvin L. Goldstein (1975) Stimulus Compounding in Classical Fear Conditioning, The Journal of General Psychology, 92:2, 261-266, DOI: 10.1080/00221309.1975.9710852 To link to this article: http://dx.doi.org/10.1080/00221309.1975.9710852
Published online: 06 Jul 2010.
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Date: 09 November 2015, At: 07:04
The Journal of General Psychology, 1975, 92, 261-266.
STIMULUS COMPOUNDING I N CLASSICAL FEAR CONDITIONING*' Indiana University at Kokomo
Downloaded by [University of Birmingham] at 07:04 09 November 2015
MELVINL. GOLDSTEIN SUMMARY The effect of stimulus compounding in classical conditioning was investigated by conditioning one group of rats to a compound CS consisting of a buzzer and light and then conditioning separate groups of rats to the individual elements of the compound CS. On hurdle-jump test trials, the group of Ss conditioned to the compound CS performed better than Ss conditioned to the elements of the compound. Strength of conditioning to each of the elements of the compound CS was about equal. There was some evidence of a summation effect resulting from conditioning to the compound CS. Strength of conditioning to the compound CS was somewhat greater than the sum of the response strengths conditioned to the elements of the compound CS.
A. INTRODUCTION Miller's ( 6 ) original acquired drive experiment demonstrated that static background apparatus cues of a shock compartment could serve as aversive CSs after conditioning with an electric shock. Goldstein (4) suggested that conditioning occurred to the static background cues of a black shock compartment when a compound US of buzzer and light was used. The effective CS was presumably a compound CS consisting of auditory and visual cues (buzzer and light) and background visual and tactual cues (black background and shock grids). Conditioning presumably occurred to the compound CS and to the background apparatus cues. Brown and Jacobs ( 2 ) have shown that performance is better after conditioning with a compound CS of light and tone than after conditioning with a buzzer alone.
* Received in the Editorial Office, Provincetown, Massachusetts, on May 9, 1974. Copyright, 1975, by The Journal Press. 1 Preparation of this report was supported in part by a supply grant awarded by the Indiana University Office of Research and Advanced Studies (Grant # 26-631-32) and by Summer Faculty Fellowships received from the Indiana University Foundation. Charles Borneman, Jr., made the drawing; Rita Martin typed the manuscript. The writer wishes to thank his wife Daidee for helpful comments during the course of this work. 261
262
JOURNAL OF GENERAL PSYCHOLOGY
Downloaded by [University of Birmingham] at 07:04 09 November 2015
The purpose of the present experiment was to compare, quantitatively, the performance of Ss given classical aversive conditioning with a compound CS and the performance of Ss conditioned to the elements of the compound CS. The relative contribution to the strength of the conditioned fear response of the elements of a compound CS was measured.
B. METHOD 1. Experimental Design There were four independent experimental groups of Ss. Repeated measurements of the hurdle-jump performance indicator were used to determine the relative effects on strength of hurdle-jump performance of classical conditioning with a compound CS of buzzer and light, buzzer only, light only, and UCS only (background apparatus cues). There were four levels of the instrumental hurdle-jump test trials (four five-trial blocks). There were five Ss in each group. Ss in Group I, the compound CS group, were conditioned in a black shock compartment with the simultaneous onset of buzzer and light serving as the CS; Ss in Group 11, the “buzzer only” group, were exposed to the onset of the buzzer, but not the light, as the CS; Ss in Group 111, the “light only” group, were exposed to the onset of the light as the CS, but not to the buzzer; Ss in Group IV, the “UCS only” group, were never exposed to buzzer or light, but the black shock compartment served as the
cs.
The UCS was a 250 v, alternating current delivered to the grid floor through a fixed resistance of 250,000 ohms (equivalent to 3 3 ma) and was the same intensity for all Ss. All Ss were given nine CS-UCS pairings with an intertrial interval of three minutes during the classical conditioning sessions and 20 trials with the compound CS during the instrumental hurdle-jump conditioning sessions. The intertrial interval during the instrumental hurdle-jump conditioning session was two minutes. Assignment of Ss to each of the four experimental groups was a t random, and the order of running the subjects was also randomized.
Subjects Ss were 20 experimentally naive, male albino rats supplied by the Holtzman Co., Madison, Wisconsin, and housed in the animal room maintained by the psychology department of Indiana University at Kokomo. They were 90 days old on arrival and 142 to 156 days old a t the start of the ex2.
MELVIN L. GOLDSTEIN
2 63
periment. The mean weights of the Ss ranged from 428 to 510 g. Ss were tamed by handling for approximately 1-2 minutes per day during a five day pre-experimental period. They were maintained ad Zib., on Purina Rat Chow and tap water.
Downloaded by [University of Birmingham] at 07:04 09 November 2015
3. Apparatus The apparatus consisted of a black conditioning box that was divided by a guillotine-type door and a hurdle into two compartments of equal size. One compartment contained a grid floor, and the other a wooden floor. The front and top of the compartment was made of Plexiglas. The black, wooden, carrying cage was covered with a hinged hardware cloth lid. It was the same size as the grid compartment. The compound CS consisted of a buzzer and light mounted on the grid side of the conditioning box. A background light was mounted above the box on the grid side. Background illumination in the grid compartment, measured with a Macbeth Illuminometer, ranged from .72 to .84 foot candles. When CS was turned on, illumination in the grid box was increased to 5.7 to 9.6 foot candles. Background noise levels in the grid compartment were 42 db on the “B” scale of a General Radio sound level meter (Type 759-B).Turning on the CS raised the noise level to 83 db. The buzzer and light were interrupted a t the rate of 2-% times per second. During the test sessions, the latency of each hurdle-jump response was measured to the nearest .01 second by a Standard Electric Timer. Further details of the apparatus have been described in an earlier report (4). 4. Procedure
An experimental session lasted for three hours and was divided into two major phases: a “classical” conditioning session, during which the CS-UCS pairings of UCS only were presented to S in the grid compartment while the guillotine door was closed, and an “instrumental” hurdle-jump conditioning session during which the compound CS was presented alone, in the grid compartment, without the UCS. For the “UCS only” condition, Ss were given nine presentations of UCS without the discrete CS during the classical conditioning sessions. The background light was on a t all times during these sessions. For the remaining groups, Ss were given nine pairings of CS and UCS during which CS pre-
Downloaded by [University of Birmingham] at 07:04 09 November 2015
2 64
JOURNAL OF GENERAL PSYCHOLOGY
ceded UCS by four seconds. Duration of UCS was one second; duration of CS was five seconds. The intertrial interval for all groups of Ss during conditioning was three minutes. A 10 minute “exploration” session was given before and after the classical conditioning session. During this session, Ss were permitted free exploration of both compartments. Instrumental hurdle-jump conditioning sessions were started 28 minutes after the last classical conditioning trial. During this session, Ss learned to jump across the hurdle from the grid-floor into the wooden-floor compartment when CS was turned on and the door separating the two compartments was opened. CS was turned off as soon as the response had been made. Ss were never given the UCS during this session, and they had been over the hurdle only during the 10 minute exploration session. Each S received 20 instrumental hurdle-jump trials with the compound CS which were separated by two minute intertrial intervals. Jntertrial intervals were spent in the black carrying cage. The response measure used was latency between onset of CS and completion of performance of the hurdle-jump test response. C.
RESULTS
The hurdle-jump latency recorded on each test trial was transformed to a reciprocal and then summed over blocks of five successive test trials for each S. The mean of a block of five reciprocals was the score used in analyses of variance which were designed to test the significance of the differences among the four experimental groups. The groups were compared two a t a time by means of Edwards’ (3) analysis of variance for repeated measures. Comparison of the “light only” CS group (Group 111) with the “background” CS group, (Group IV) yielded an insignificant F [ F ( 1,8) = 1.06). Comparison of the “buzzer only” CS group (Group IT) with the “background” CS group (Group I V ) yielded an insignificant F ( F ( 1,X) = 1.441. Comparison of the “buzzer only” CS group (Group 11) with the “buzzer and light” CS group, (Group I ) yielded an F which was just short of significant a t the .05 level of confidence IF( 1,8) = 3.531. Comparison of the “buzzer and light” CS group (Group I) with the “background” CS group (Group TV) yielded an F which was significant beyond the .01 level of confidence [ F ( 1,8) = 33.661. The performance functions for Groups I-IV are illustrated in Figure 1.
265
MELVIN L. GOLDSTEIN
- 1.50v)
&--A
\ -
5
z
-
BUZZER CS BACKGROUND-CS LIGHT-CS
c---
V w
1.00-
W
l-
a Downloaded by [University of Birmingham] at 07:04 09 November 2015
-L
-J
a ; .fa%
0
W
[L
z a w
I
1
FIGURE 1 PERFORMANCE
FUNCTIONS FOR
CONDITIONING
TO A S T I M U L U S C O M P O U N D AND TO
ITS
ELEMENTS
D. DISCUSSION The general findings of the present experiment are that strength of conditioning is about equal to a buzzer CS (Group 11), a light CS (Group 111), and a background CS (Group I V ) , the elements of the compound CS. Conditioning to the compound CS of buzzer, light, and background (Group I ) , however, yields better performance than does conditioning to any of the individual elements of the compound. The magnitude of the conditioned response to the compound CS is, in general, equal to or greater than the sum of the strengths of the conditioned responses to the individual elements of the compound CS (Figure 1) . The experiment, therefore, yields some evidence for a summation effect of the compound CS in classical fear conditioning. There is some small amount of evidence for summation effects resulting from stimulus compounding in experimental situations other than the conditioned fear experiment. Hull ( 5 ) very early reported a summation effect for the conditioned eyelid reflex and for the conditioning of respiration disturbances. More recently, Booth and Hammond (1) have reported that rats overtrained in the conditioned emotional response (CER) will show
266
JOURNAL O F GENERAL PSYCHOLOGY
Downloaded by [University of Birmingham] at 07:04 09 November 2015
evidence of summation due to stimulus compounding (i.e., greater response strength to the compound stimulus than to the components). The summation effect of stimulus compounding seems to have a certain degree of generality, although there are few substantial experimental demonstrations of the phenomenon in the literature ( 7 , 8 ) . The phenomenon may, possibly, be based upon a stimulus intensity dynamism effect resulting from the combinatian of conditioned stimuli from several different sensory modalities.
REFERENCES 1. BOOTH,J. H., & HAMMOND, L. J. Configural conditioning: Greater fear in rats to compound than component through overtraining of the compound. J. Exper. Psychol., 1971, 87, 255-262. 2. BROWN,J. S., & JACOBS, A. The role of fear in the motivation and acquisition of responses. J. Exper. Psychol., 1949, 39, 747-759. 3. EDWARDS, A. L. Experimental Design in Psychological Research. New York: Holt, Rinehart & Winston, 1960. 4. GOLDSTEIN, M. L. Acquired drive strength as a joint function of shock intensity and number of acquisition trials. J. Exper. Psychol., 1960, 60, 349-358. 5. HULL, C. L. Learning: 11. The factor of the conditioned reflex. In C. Murchison (Ed.), Handbook of General Experimental Psychology. Worcester, Mass.: Clark Univ. Press, 1934. 6. MILLER,N. E. Studies of fear as an acquirable drive: I. Fear as motivation and fear-reduction as reinforcement in the learning of new responses. 1. Exper. Psychol. 1948, 38, 89-101. 7. RAZRAN, G. Empirical codifications and specific theoretical implication of compoundstimulus conditioning: Perception. In W. F. Prokasy (Ed.), Classical Conditioning: A Symposizcm. New York: Appleton-Century-Crofts, 1965. 8. WICKENS,D. D. Compound Conditioning in Humans and Cats. In W. F. Prokasy (Ed.), Classical Conditioning: A Symposium. New York: Appleton-CenturyCrofts, 1965.
Department of Psychology Indiana University at Kokomo 2300 South Washington Street Kokomo, Indiana 46901
ISSN: 0022-1309 (Print) 1940-0888 (Online) Journal homepage: http://www.tandfonline.com/loi/vgen20
Stimulus Compounding in Classical Fear Conditioning Melvin L. Goldstein To cite this article: Melvin L. Goldstein (1975) Stimulus Compounding in Classical Fear Conditioning, The Journal of General Psychology, 92:2, 261-266, DOI: 10.1080/00221309.1975.9710852 To link to this article: http://dx.doi.org/10.1080/00221309.1975.9710852
Published online: 06 Jul 2010.
Submit your article to this journal
Article views: 14
View related articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=vgen20 Download by: [University of Birmingham]
Date: 09 November 2015, At: 07:04
The Journal of General Psychology, 1975, 92, 261-266.
STIMULUS COMPOUNDING I N CLASSICAL FEAR CONDITIONING*' Indiana University at Kokomo
Downloaded by [University of Birmingham] at 07:04 09 November 2015
MELVINL. GOLDSTEIN SUMMARY The effect of stimulus compounding in classical conditioning was investigated by conditioning one group of rats to a compound CS consisting of a buzzer and light and then conditioning separate groups of rats to the individual elements of the compound CS. On hurdle-jump test trials, the group of Ss conditioned to the compound CS performed better than Ss conditioned to the elements of the compound. Strength of conditioning to each of the elements of the compound CS was about equal. There was some evidence of a summation effect resulting from conditioning to the compound CS. Strength of conditioning to the compound CS was somewhat greater than the sum of the response strengths conditioned to the elements of the compound CS.
A. INTRODUCTION Miller's ( 6 ) original acquired drive experiment demonstrated that static background apparatus cues of a shock compartment could serve as aversive CSs after conditioning with an electric shock. Goldstein (4) suggested that conditioning occurred to the static background cues of a black shock compartment when a compound US of buzzer and light was used. The effective CS was presumably a compound CS consisting of auditory and visual cues (buzzer and light) and background visual and tactual cues (black background and shock grids). Conditioning presumably occurred to the compound CS and to the background apparatus cues. Brown and Jacobs ( 2 ) have shown that performance is better after conditioning with a compound CS of light and tone than after conditioning with a buzzer alone.
* Received in the Editorial Office, Provincetown, Massachusetts, on May 9, 1974. Copyright, 1975, by The Journal Press. 1 Preparation of this report was supported in part by a supply grant awarded by the Indiana University Office of Research and Advanced Studies (Grant # 26-631-32) and by Summer Faculty Fellowships received from the Indiana University Foundation. Charles Borneman, Jr., made the drawing; Rita Martin typed the manuscript. The writer wishes to thank his wife Daidee for helpful comments during the course of this work. 261
262
JOURNAL OF GENERAL PSYCHOLOGY
Downloaded by [University of Birmingham] at 07:04 09 November 2015
The purpose of the present experiment was to compare, quantitatively, the performance of Ss given classical aversive conditioning with a compound CS and the performance of Ss conditioned to the elements of the compound CS. The relative contribution to the strength of the conditioned fear response of the elements of a compound CS was measured.
B. METHOD 1. Experimental Design There were four independent experimental groups of Ss. Repeated measurements of the hurdle-jump performance indicator were used to determine the relative effects on strength of hurdle-jump performance of classical conditioning with a compound CS of buzzer and light, buzzer only, light only, and UCS only (background apparatus cues). There were four levels of the instrumental hurdle-jump test trials (four five-trial blocks). There were five Ss in each group. Ss in Group I, the compound CS group, were conditioned in a black shock compartment with the simultaneous onset of buzzer and light serving as the CS; Ss in Group 11, the “buzzer only” group, were exposed to the onset of the buzzer, but not the light, as the CS; Ss in Group 111, the “light only” group, were exposed to the onset of the light as the CS, but not to the buzzer; Ss in Group IV, the “UCS only” group, were never exposed to buzzer or light, but the black shock compartment served as the
cs.
The UCS was a 250 v, alternating current delivered to the grid floor through a fixed resistance of 250,000 ohms (equivalent to 3 3 ma) and was the same intensity for all Ss. All Ss were given nine CS-UCS pairings with an intertrial interval of three minutes during the classical conditioning sessions and 20 trials with the compound CS during the instrumental hurdle-jump conditioning sessions. The intertrial interval during the instrumental hurdle-jump conditioning session was two minutes. Assignment of Ss to each of the four experimental groups was a t random, and the order of running the subjects was also randomized.
Subjects Ss were 20 experimentally naive, male albino rats supplied by the Holtzman Co., Madison, Wisconsin, and housed in the animal room maintained by the psychology department of Indiana University at Kokomo. They were 90 days old on arrival and 142 to 156 days old a t the start of the ex2.
MELVIN L. GOLDSTEIN
2 63
periment. The mean weights of the Ss ranged from 428 to 510 g. Ss were tamed by handling for approximately 1-2 minutes per day during a five day pre-experimental period. They were maintained ad Zib., on Purina Rat Chow and tap water.
Downloaded by [University of Birmingham] at 07:04 09 November 2015
3. Apparatus The apparatus consisted of a black conditioning box that was divided by a guillotine-type door and a hurdle into two compartments of equal size. One compartment contained a grid floor, and the other a wooden floor. The front and top of the compartment was made of Plexiglas. The black, wooden, carrying cage was covered with a hinged hardware cloth lid. It was the same size as the grid compartment. The compound CS consisted of a buzzer and light mounted on the grid side of the conditioning box. A background light was mounted above the box on the grid side. Background illumination in the grid compartment, measured with a Macbeth Illuminometer, ranged from .72 to .84 foot candles. When CS was turned on, illumination in the grid box was increased to 5.7 to 9.6 foot candles. Background noise levels in the grid compartment were 42 db on the “B” scale of a General Radio sound level meter (Type 759-B).Turning on the CS raised the noise level to 83 db. The buzzer and light were interrupted a t the rate of 2-% times per second. During the test sessions, the latency of each hurdle-jump response was measured to the nearest .01 second by a Standard Electric Timer. Further details of the apparatus have been described in an earlier report (4). 4. Procedure
An experimental session lasted for three hours and was divided into two major phases: a “classical” conditioning session, during which the CS-UCS pairings of UCS only were presented to S in the grid compartment while the guillotine door was closed, and an “instrumental” hurdle-jump conditioning session during which the compound CS was presented alone, in the grid compartment, without the UCS. For the “UCS only” condition, Ss were given nine presentations of UCS without the discrete CS during the classical conditioning sessions. The background light was on a t all times during these sessions. For the remaining groups, Ss were given nine pairings of CS and UCS during which CS pre-
Downloaded by [University of Birmingham] at 07:04 09 November 2015
2 64
JOURNAL OF GENERAL PSYCHOLOGY
ceded UCS by four seconds. Duration of UCS was one second; duration of CS was five seconds. The intertrial interval for all groups of Ss during conditioning was three minutes. A 10 minute “exploration” session was given before and after the classical conditioning session. During this session, Ss were permitted free exploration of both compartments. Instrumental hurdle-jump conditioning sessions were started 28 minutes after the last classical conditioning trial. During this session, Ss learned to jump across the hurdle from the grid-floor into the wooden-floor compartment when CS was turned on and the door separating the two compartments was opened. CS was turned off as soon as the response had been made. Ss were never given the UCS during this session, and they had been over the hurdle only during the 10 minute exploration session. Each S received 20 instrumental hurdle-jump trials with the compound CS which were separated by two minute intertrial intervals. Jntertrial intervals were spent in the black carrying cage. The response measure used was latency between onset of CS and completion of performance of the hurdle-jump test response. C.
RESULTS
The hurdle-jump latency recorded on each test trial was transformed to a reciprocal and then summed over blocks of five successive test trials for each S. The mean of a block of five reciprocals was the score used in analyses of variance which were designed to test the significance of the differences among the four experimental groups. The groups were compared two a t a time by means of Edwards’ (3) analysis of variance for repeated measures. Comparison of the “light only” CS group (Group 111) with the “background” CS group, (Group IV) yielded an insignificant F [ F ( 1,8) = 1.06). Comparison of the “buzzer only” CS group (Group IT) with the “background” CS group (Group I V ) yielded an insignificant F ( F ( 1,X) = 1.441. Comparison of the “buzzer only” CS group (Group 11) with the “buzzer and light” CS group, (Group I ) yielded an F which was just short of significant a t the .05 level of confidence IF( 1,8) = 3.531. Comparison of the “buzzer and light” CS group (Group I) with the “background” CS group (Group TV) yielded an F which was significant beyond the .01 level of confidence [ F ( 1,8) = 33.661. The performance functions for Groups I-IV are illustrated in Figure 1.
265
MELVIN L. GOLDSTEIN
- 1.50v)
&--A
\ -
5
z
-
BUZZER CS BACKGROUND-CS LIGHT-CS
c---
V w
1.00-
W
l-
a Downloaded by [University of Birmingham] at 07:04 09 November 2015
-L
-J
a ; .fa%
0
W
[L
z a w
I
1
FIGURE 1 PERFORMANCE
FUNCTIONS FOR
CONDITIONING
TO A S T I M U L U S C O M P O U N D AND TO
ITS
ELEMENTS
D. DISCUSSION The general findings of the present experiment are that strength of conditioning is about equal to a buzzer CS (Group 11), a light CS (Group 111), and a background CS (Group I V ) , the elements of the compound CS. Conditioning to the compound CS of buzzer, light, and background (Group I ) , however, yields better performance than does conditioning to any of the individual elements of the compound. The magnitude of the conditioned response to the compound CS is, in general, equal to or greater than the sum of the strengths of the conditioned responses to the individual elements of the compound CS (Figure 1) . The experiment, therefore, yields some evidence for a summation effect of the compound CS in classical fear conditioning. There is some small amount of evidence for summation effects resulting from stimulus compounding in experimental situations other than the conditioned fear experiment. Hull ( 5 ) very early reported a summation effect for the conditioned eyelid reflex and for the conditioning of respiration disturbances. More recently, Booth and Hammond (1) have reported that rats overtrained in the conditioned emotional response (CER) will show
266
JOURNAL O F GENERAL PSYCHOLOGY
Downloaded by [University of Birmingham] at 07:04 09 November 2015
evidence of summation due to stimulus compounding (i.e., greater response strength to the compound stimulus than to the components). The summation effect of stimulus compounding seems to have a certain degree of generality, although there are few substantial experimental demonstrations of the phenomenon in the literature ( 7 , 8 ) . The phenomenon may, possibly, be based upon a stimulus intensity dynamism effect resulting from the combinatian of conditioned stimuli from several different sensory modalities.
REFERENCES 1. BOOTH,J. H., & HAMMOND, L. J. Configural conditioning: Greater fear in rats to compound than component through overtraining of the compound. J. Exper. Psychol., 1971, 87, 255-262. 2. BROWN,J. S., & JACOBS, A. The role of fear in the motivation and acquisition of responses. J. Exper. Psychol., 1949, 39, 747-759. 3. EDWARDS, A. L. Experimental Design in Psychological Research. New York: Holt, Rinehart & Winston, 1960. 4. GOLDSTEIN, M. L. Acquired drive strength as a joint function of shock intensity and number of acquisition trials. J. Exper. Psychol., 1960, 60, 349-358. 5. HULL, C. L. Learning: 11. The factor of the conditioned reflex. In C. Murchison (Ed.), Handbook of General Experimental Psychology. Worcester, Mass.: Clark Univ. Press, 1934. 6. MILLER,N. E. Studies of fear as an acquirable drive: I. Fear as motivation and fear-reduction as reinforcement in the learning of new responses. 1. Exper. Psychol. 1948, 38, 89-101. 7. RAZRAN, G. Empirical codifications and specific theoretical implication of compoundstimulus conditioning: Perception. In W. F. Prokasy (Ed.), Classical Conditioning: A Symposizcm. New York: Appleton-Century-Crofts, 1965. 8. WICKENS,D. D. Compound Conditioning in Humans and Cats. In W. F. Prokasy (Ed.), Classical Conditioning: A Symposium. New York: Appleton-CenturyCrofts, 1965.
Department of Psychology Indiana University at Kokomo 2300 South Washington Street Kokomo, Indiana 46901
