Journal o) Personality and Social Psychology 1976, Vol. 33, No. 1, 107-116
Physiological Mediation of Attitudinal Responses Richard A. Detweiler Drew University
Mark P. Zanna University of Waterloo, Ontario, Canada
A study was undertaken to try to ascertain the best model of the relationship between stimuli, physiological responses, and attitudes. Subjects were asked to indicate their attitudes toward various nations after having received various bogus information about how they responded physiologically to the stimuli. The results indicate the following: (a) In general, attitudes appear to be physiologically mediated; (b) physiological mediation of attitudes is strongest when prior knowledge about the stimuli is low but is independent of prior attitudes about the stimuli; (c) bogus physiological feedback does not seem to be verbally mediated; and (d) the most fruitful distinction between types of bogus feedback is between any feedback versus no feedback, not between change versus no change or between increase versus decrease in response.
What is the relationship between external stimuli, physiological changes, and attitudes? This has been a question of interest both historically and more recently within an attribution theory context. A number of relationships have been suggested. For example, James (1894) postulated that perception of an exciting stimulus causes a physiological response. Cooper (19S9) hypothesized (and demonstrated) that with prejudice, "group name stimuli which elicit the greatest amounts of emotionality (as measured by physiological change of G.S.R.) should identify those groups as objects of relatively strong prejudiced attitudes . . ." (p. 318). Schachter and Singer (1962) found that situational cues, when added to artificially produced physiological arousal, caused subjects to express emotion. Bramel, Bell, and Margulis (1965) found that the interaction of a stimulus with nonveridical cognitions about physiological changes resulted in attitude change. Valins (1966) found that cognitions about physiological change in response to stimuli caused changes in emotion. Finally, Goldstein, Fink, and Mettee (1972) found that in nonemotional situations, cognitive cues about physio-
The authors wish to thank E. Tory Higgins and Philip K. Jensen for comments on an earlier draft of the manuscript. Requests for reprints should be sent to Mark P. Zanna, Department of Psychology, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1.
logical states cause both emotion and physiological change independently, whereas in emotional situations, physiological change alone causes emotion. Thus, the above studies have examined various aspects of the possible relationships between external stimuli, physiological state, and attitude. However, for a number of reasons, the possible causal relationships among these factors are not clear on the basis of these studies. First, with the exception of Goldstein, Fink, and Mettee (1972), the three factors have not been examined simultaneously. Second, bogus feedback regarding one's physiological state has been widely used, and yet the actual effect of types of feedback (positive change, negative change, no change, or no feedback) is not clear. For example, Valins (1966) found that the direction of change (increase or decrease) of bogus heart rate feedback was irrelevant, so it was assumed by those following that the relevant distinction was change versus no change. However, this has not been systematically studied. Third, the actual mechanism by which bogus feedback actually works has not been established. Implicit in much of attribution theory is the idea of verbal labeling: An individual may have no built-in knowledge of the meaning of any particular internal response and must in some way (e.g., by examining appropriate external cues) infer an explanatory label from which beliefs, attitudes, feelings, etc. can be inferred. In the context of
107
RICHARD A. DETWEILER AND MARK P. ZANNA
108
bogus feedback, Valins (1966) cites this process explicitly: As such it is hypothesized that the cognition, "That girl has affected my heart rate," will induce subjects to consider the girl more attractive or appealing than the cognition, "That girl has not affected my heart rate." . . . Thus, under the appropriate cognitive conditions (highly attractive females), feedback indicating that heart rate has decreased should affect the labeling of emotional stimuli . . . (p. 401)
In other words, it has been assumed that bogus feedback is effective because there is some kind of mediation through verbal labeling. However, this indirect effect of bogus feedback has not in fact been demonstrated. It could act more directly without being verbally labeled. Fourth, the dependent measure in these studies has frequently been emotion. However, the meaning of emotion is inconsistent. In some cases it is equated with physiological response and in other cases it is not differentiated from attitude. What are the possible relationships between stimuli, physiological responses, and attitudes? (Stimuli, as used here, is meant to be a broader term that includes environmental or situational stimuli, information about physiological state, information about the meaning of physiological change, etc.) Assuming that the stimulus is antecedent, Figure 1 shows six possible models of these relationships. Figure la shows a parallel relationship: Some feature of the stimulus causes both a physiological and an attitudinal response, but physiology and attitude are independent of one another. Figure Ib shows a stimulus property causing a physiological response but no attiP
A
A
A (a)
P
P
(b)
(c)
P
P
1 A (d)
(e)
A (f)
FIBTTRE 1. Relationships between stimuli (S), physiological change (P), and attitudes (A), given an antecedent stimulus.
tudinal response, with physiology independent of attitude. Figure Ic shows just the opposite pattern, with a stimulus property causing only an attitudinal response. Figures Id and le show a series relationship, with a stimulus property causing a physiological response that in turn causes an attitudinal response (in the first case) and a stimulus property causing an attitudinal response that in turn causes a physiological response (in the second case). Figure If shows total independence between stimulus, physiology, and attitude. The basic question to be addressed here is which model of the relationship between stimuli, physiological responses, and attitudes is valid. However, several other questions are also relevant. First, what specifically is the effect of different types of bogus physiological feedback? Second, if one of the above models appears useful and valid, how general is it? Specifically, does it hold when knowledge about an environmental stimulus is high or low or when prior attitudes are positive or negative? Third, is the effect of bogus physiological feedback indirect (through verbal mediation) or direct (acting without verbal mediation) ? To answer these questions, subjects were placed in a situation in which they were asked to indicate their attitudes toward various nations after having received different types of information about how they responded physiologically to the stimuli. Although the physiological feedback was false, actual heart rate was continuously monitored. Thus, there was one main independent variable, bogus physiological feedback (increase, no change, decrease, or no feedback), and two dependent variables, attitude toward the nation in question and actual physiological change. In order to assess the consistency of the feedback effect, each bogus feedback condition was replicated four times by each subject, resulting in an order factor as a second independent variable. Additionally, in order to investigate the strength and generality of any relationship between the independent and dependent variables, the nation stimuli varied along two dimensions, subjects' positiveness of prior attitude toward the nations and subjects' degree of knowledge
PHYSIOLOGICAL MEDIATION OF ATTITUDINAL RESPONSES about the nations. Finally, in order to maximize the effect of the feedback manipulation as well as to give tentative evidence whether bogus physiological feedback is effective directly or by means of verbal mediation, each feedback condition was verbally labeled by the experimenter to indicate a particular emotional response. Increase was labeled as negative, no change as neutral, and decrease as a positive emotional response.1 In sum, the experiment was a 4 X 4 withinsubjects factorial design with bogus physiological feedback (increase, no change, decrease, or no feedback) and stimulus order (presented first, second, third, or fourth within each feedback condition) as independent variables and heart rate change and attitudes as dependent variables. Additionally, there were the covaried factors of prior knowledge and also prior attitude about each nation stimulus, and the verbal label applied to each bogus feedback condition. METHOD Design The design is a 4 X 4 factorial with repeated measures on both factors. The first factor is a bogus physiological feedback factor consisting of nonveridical increase, decrease, or no change in physiological response, or no feedback at all. The second factor was an order factor, since each subject replicated each feedback condition four times. Hence, each subject recorded 16 observations in response to 16 different nation name stimuli. Combinations of nation with feedback condition were counterbalanced by means of four different Latin squares (four subject groups with five subjects per group), and order of presentation of the 16 nations was controlled by means of five different total randomizations (one subject in each subject group received each random order). The nation stimuli were chosen on the basis of responses to a questionnaire administered to each subject 1 week prior to the experimental session. This questionnaire was designed to ascertain subjects' attitudes and knowledge about a number of nations, and nation stimuli were chosen from this pretest to vary on the attitude and knowledge dimensions. Subjects Twenty-two university students volunteered as paid subjects to participate in a two-part "student opinion study." Two subjects were excluded from the analysis because of suspicion. The resultant sample consisted of 11 males and 9 females.
109
Apparatus Heart rate was measured by means of a Sanborn Model 60 twin-pen electrocardiograph (EKG). Bipolar limb leads (Lead II EKG) recorded the EKG. The bogus physiological feedback device was an EKG-GSR Simulator 2 that consisted of a large zero-center galvanometer and a speaker, which were operated remotely by the experimenter.3 The galvanometer indicated galvanic skin response (GSR) in either the positive or negative direction by a +100 to 0 to —100 scale. The heart rate consisted of electronically generated blips heard over the loudspeaker, which could be varied from approximately 45 to ISO beats per minute. Procedure The experiment was conducted in two parts separated by approximately 1 week. When subjects came to the first session, they were given a selfadministered questionnaire that included items designed to assess their attitude toward (very negative to very positive on a scale from 0 to 100, respectively, with SO as a midpoint), and extent of knowledge about (never heard of, scored 0, to great knowledge, scored 5) 41 alphabetically arranged nations, These nations were chosen on the basis of a pilot study to vary widely on both the knowledge and attitude dimensions, as well as to be distributed among all geographic areas of the world. In general, pilot study results held in the present study. The second session was arranged for approximately 1 week later. Upon arrival, the subject was seated in an empty office by the experimenter, who apologized because there would be a delay because of equipment trouble. After a reasonable wait, the subjects was first taken to the experimenter's control room and was shown the polygraph machine. It was explained that the delay was due to the polygraph, which was very old and working improperly. The experimenter "tore off" an artificially produced EKG and GSR paper tape record and took it with him as he ushered the subject back into the experimental room. Subjects were then told that the purpose of the study was to assess differences in opinions about different aspects (whether one was rating a nation, 1
These labels are consistent with Graham and Clifton's (1966) thesis that the accelerative component of heart rate is a defensive one. 2 The EKG-GSR Simulator was engineered and built by Charles Crane and Joseph Lewandowski. It electronically generated remarkably real-sounding audio heart rate pulses as well as having the visual galvanic skin response galvanometer. 8 Bogus feedback was given on both heart rate and galvanic skin response to maximize the strength of the manipulation. Both actual heart rate and galvanic skin response were recorded; however, because of a problem in the GSR recording technique, those data were not usable.
no
RICHARD A. DETWEILER AND MARK P. ZANNA
its leaders, or its people) of different countries, and that the country names would be presented on an automatically sequenced paper tape. The experimenter then told the subject that his advisor was also interested in how small stimuli can be and still cause physiological responses and that he wanted to use this opportunity "where sequential stimuli would be presented anyway" to also record physiological responses. At this point the meaning of EKG and GSR was explained, and the cognitive labels for the meaning of changes (increase, decrease, or no change) was given. The experimenter then continued: Now, recording this would have been pretty easy, except for the equipment trouble. Here's the tape the polygraph recorded on the last person [the artificially produced recording which had normal as well as obviously abnormal EKG and GSR patterns was shown to the subject] . . . I borrowed this apparatus here [referring to the bogus feedback device] from the biofeedback laboratories where they train people to control their heart rate and skin response by watching their own response on this equipment. . . . The fellows from the electronic shop wired it into the circuit so that I can use it to double-check the reading the polygraph gives so I'll know for sure when it's not working right . . . The feedback device is wired in on the other side of the wall where I can't see it ... Would you mind writing down for me what happens, and then I can compare afterward what you recorded with the paper tape? After subjects indicated that they would record what they presumed to be their actual physiological responses, the total procedure was described. First, they were to push a button that would advance the stimulus tape to a blank and turn on the physiological monitoring equipment. After about 10 seconds, the tape would automatically advance to a stimulus. The subject was to read the stimulus and then take note of any physiological changes, which he would then record on the appropriate sheet. The "meaning" (positive, neutral, or negative feelings) of the various physiological changes was again stressed. After this, the subject was to go on to the "real" purpose of this study and fill out the attitude measures. The subject was then told that the physiological feedback equipment would turn off automatically after about 2$ seconds had elapsed, and would remain off until the button was pushed again. Throughout, an effort was made to dissociate the physiological measurements from the purported purpose of the study. Any questions were then answered and the subjects were connected to the polygraph by means of skin electrodes. The experimenter finally added: If the monitoring equipment doesn't come on, don't worry about it—that just means that I have the wiring disconnected on the other side. I'm going to try to fix it while you're hooked up to it since I have to have heart rate and skin response signals coming into it to figure out what's wrong.
The experimenter then left the room, and after a 3-minute delay to allow heart rate to reach a resting level, the session began. Prior to the 16 experimental trials, 2 credibility trials occurred. On these trials, the bogus feedback was given to be consistent with the subject's attitudes as expressed on the prerating questionnaire. These credibility-trial nation stimuli were chosen individually for each subject; they were one very liked and one very disliked nation that were not being used in the experimental trials. During the 16 experimental trials each subject heard his or her heart rate and saw his or her skin responses (in random order) increase on four trials, decrease on four trials, and not change on four trials. On the remaining four trials, the equipment did not come on at all. The bogus heart rate baseline was set independently for each subject to correspond with actual heart rate as measured by the Sanborn recorder. Changes in bogus heart rate consisted of an increase or decrease of approximately 15 beats per minute. If a subject did not indicate that his or her heart rate increased (or decreased, as the case might be), the amount of increase (or decrease) was partially corrected by increasing (or decreasing) the bogus heart rate feedback until a change was indicated in the desired direction. The bogus GSR baseline was zero for all subjects and increased or decreased by 65 to 85 points on a 100-point scale. In the neutral feedback condition the needle remained within 5 points of zero. After the final trial, debriefing for suspicion was undertaken, followed by an explanation of the true nature of the experiment. Subsequent questions were answered, and the importance of secrecy concerning the experiment was stressed.
Dependent Variables Heart rate. The measure of change in heart rate was adapted from that advocated by Beecroft (1966). The heart rate before each stimulus was ascertained by calculating the mean interbeat interval (IBI) of the last three beats prior to stimulus presentation. The after heart rate was determined by calculating the mean IBI of the three beats beginning with the beat closest to the fifth second after stimulus onset.4 This time lag was used because heart rate latency is (according to studies 4 Analyses using the 2- to 5-second interval as the post heart rate measure gave results similar to those reported here. An additional examination of the heart rate response curve was undertaken by randomly selecting one trial per subject and calculating a mean response curve. These data indicated a principally monophasic deceleration, with a possible diphasic effect in which deceleration occurred for the first two beats, followed by acceleration on the third beat, followed immediately by greater deceleration. Maximum deceleration was reached by about the sixth beat (at about 5 seconds after the stimulus).
PHYSIOLOGICAL MEDIATION OF ATTITUDINAL RESPONSES cited by Beecroft) about 2 seconds, reaching its peak at about 5 to 7 seconds. The actual heart rate measure employed was the change in mean heart rate IBI from before to after each stimulus onset. Longer recording intervals were not used, since diphasic heart rate changes can make dependent measures based on the mean change of longer intervals invalid indicators of heart rate change (see Johnson & Lubin, 1972). Prior to the first trial, about 3 minutes were allowed to elapse from the time the experimenter left the subject until the first stimulus was presented, to allow the heart rate to reach a resting level. After that time, the pace of the trials was in part determined by the subject who pushed a button to indicate readiness for the next trial. The average time between the delivery of the various bogus feedback manipulations was approximately 3 minutes. Attitude. The measure of attitude consisted of 20 adjectives, each of which was responded to by placing a mark on a line to indicate the degree to which that particular trait characterized the nation stimulus. The mark was then coded into a value with a ruler on a 100-point scale. The 20 adjectives in fact consisted of 10 polar opposite pairs as follows: unintelligent-intelligent, unpredictable-predictable, trustworthy-untrustworthy, cruel-kind, modest-arrogant, lazy-hardworking, friendly-unfriendly, generous-selfish, rude-polite, and peace-orientedwar-oriented. The positive traits were scored on a scale of 0 to +100, with +100 indicating complete possession. The negative traits were scored on a scale of 0 to —100, with —100 indicating complete possession. The main attitude measure was created by averaging the responses to these scales. Thus, if a subject felt that a nation possessed the 10 positive traits and did not possess the 10 negative traits he or she received a mean score of +50; if a subject felt the exact opposite, he or she would receive a mean score of —50. TABLE 1 ANALYSES OF VARIANCE or MEAN ATTITUDE AND HEART RATE CHANGE Source
df
MS
Dependent measure: attitude Bogus feedback Order Feedback X Order Residual
3 3 9 285
15.94 26.88 20.22 44.08
Physiological Mediation of Attitudinal Responses Richard A. Detweiler Drew University
Mark P. Zanna University of Waterloo, Ontario, Canada
A study was undertaken to try to ascertain the best model of the relationship between stimuli, physiological responses, and attitudes. Subjects were asked to indicate their attitudes toward various nations after having received various bogus information about how they responded physiologically to the stimuli. The results indicate the following: (a) In general, attitudes appear to be physiologically mediated; (b) physiological mediation of attitudes is strongest when prior knowledge about the stimuli is low but is independent of prior attitudes about the stimuli; (c) bogus physiological feedback does not seem to be verbally mediated; and (d) the most fruitful distinction between types of bogus feedback is between any feedback versus no feedback, not between change versus no change or between increase versus decrease in response.
What is the relationship between external stimuli, physiological changes, and attitudes? This has been a question of interest both historically and more recently within an attribution theory context. A number of relationships have been suggested. For example, James (1894) postulated that perception of an exciting stimulus causes a physiological response. Cooper (19S9) hypothesized (and demonstrated) that with prejudice, "group name stimuli which elicit the greatest amounts of emotionality (as measured by physiological change of G.S.R.) should identify those groups as objects of relatively strong prejudiced attitudes . . ." (p. 318). Schachter and Singer (1962) found that situational cues, when added to artificially produced physiological arousal, caused subjects to express emotion. Bramel, Bell, and Margulis (1965) found that the interaction of a stimulus with nonveridical cognitions about physiological changes resulted in attitude change. Valins (1966) found that cognitions about physiological change in response to stimuli caused changes in emotion. Finally, Goldstein, Fink, and Mettee (1972) found that in nonemotional situations, cognitive cues about physio-
The authors wish to thank E. Tory Higgins and Philip K. Jensen for comments on an earlier draft of the manuscript. Requests for reprints should be sent to Mark P. Zanna, Department of Psychology, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1.
logical states cause both emotion and physiological change independently, whereas in emotional situations, physiological change alone causes emotion. Thus, the above studies have examined various aspects of the possible relationships between external stimuli, physiological state, and attitude. However, for a number of reasons, the possible causal relationships among these factors are not clear on the basis of these studies. First, with the exception of Goldstein, Fink, and Mettee (1972), the three factors have not been examined simultaneously. Second, bogus feedback regarding one's physiological state has been widely used, and yet the actual effect of types of feedback (positive change, negative change, no change, or no feedback) is not clear. For example, Valins (1966) found that the direction of change (increase or decrease) of bogus heart rate feedback was irrelevant, so it was assumed by those following that the relevant distinction was change versus no change. However, this has not been systematically studied. Third, the actual mechanism by which bogus feedback actually works has not been established. Implicit in much of attribution theory is the idea of verbal labeling: An individual may have no built-in knowledge of the meaning of any particular internal response and must in some way (e.g., by examining appropriate external cues) infer an explanatory label from which beliefs, attitudes, feelings, etc. can be inferred. In the context of
107
RICHARD A. DETWEILER AND MARK P. ZANNA
108
bogus feedback, Valins (1966) cites this process explicitly: As such it is hypothesized that the cognition, "That girl has affected my heart rate," will induce subjects to consider the girl more attractive or appealing than the cognition, "That girl has not affected my heart rate." . . . Thus, under the appropriate cognitive conditions (highly attractive females), feedback indicating that heart rate has decreased should affect the labeling of emotional stimuli . . . (p. 401)
In other words, it has been assumed that bogus feedback is effective because there is some kind of mediation through verbal labeling. However, this indirect effect of bogus feedback has not in fact been demonstrated. It could act more directly without being verbally labeled. Fourth, the dependent measure in these studies has frequently been emotion. However, the meaning of emotion is inconsistent. In some cases it is equated with physiological response and in other cases it is not differentiated from attitude. What are the possible relationships between stimuli, physiological responses, and attitudes? (Stimuli, as used here, is meant to be a broader term that includes environmental or situational stimuli, information about physiological state, information about the meaning of physiological change, etc.) Assuming that the stimulus is antecedent, Figure 1 shows six possible models of these relationships. Figure la shows a parallel relationship: Some feature of the stimulus causes both a physiological and an attitudinal response, but physiology and attitude are independent of one another. Figure Ib shows a stimulus property causing a physiological response but no attiP
A
A
A (a)
P
P
(b)
(c)
P
P
1 A (d)
(e)
A (f)
FIBTTRE 1. Relationships between stimuli (S), physiological change (P), and attitudes (A), given an antecedent stimulus.
tudinal response, with physiology independent of attitude. Figure Ic shows just the opposite pattern, with a stimulus property causing only an attitudinal response. Figures Id and le show a series relationship, with a stimulus property causing a physiological response that in turn causes an attitudinal response (in the first case) and a stimulus property causing an attitudinal response that in turn causes a physiological response (in the second case). Figure If shows total independence between stimulus, physiology, and attitude. The basic question to be addressed here is which model of the relationship between stimuli, physiological responses, and attitudes is valid. However, several other questions are also relevant. First, what specifically is the effect of different types of bogus physiological feedback? Second, if one of the above models appears useful and valid, how general is it? Specifically, does it hold when knowledge about an environmental stimulus is high or low or when prior attitudes are positive or negative? Third, is the effect of bogus physiological feedback indirect (through verbal mediation) or direct (acting without verbal mediation) ? To answer these questions, subjects were placed in a situation in which they were asked to indicate their attitudes toward various nations after having received different types of information about how they responded physiologically to the stimuli. Although the physiological feedback was false, actual heart rate was continuously monitored. Thus, there was one main independent variable, bogus physiological feedback (increase, no change, decrease, or no feedback), and two dependent variables, attitude toward the nation in question and actual physiological change. In order to assess the consistency of the feedback effect, each bogus feedback condition was replicated four times by each subject, resulting in an order factor as a second independent variable. Additionally, in order to investigate the strength and generality of any relationship between the independent and dependent variables, the nation stimuli varied along two dimensions, subjects' positiveness of prior attitude toward the nations and subjects' degree of knowledge
PHYSIOLOGICAL MEDIATION OF ATTITUDINAL RESPONSES about the nations. Finally, in order to maximize the effect of the feedback manipulation as well as to give tentative evidence whether bogus physiological feedback is effective directly or by means of verbal mediation, each feedback condition was verbally labeled by the experimenter to indicate a particular emotional response. Increase was labeled as negative, no change as neutral, and decrease as a positive emotional response.1 In sum, the experiment was a 4 X 4 withinsubjects factorial design with bogus physiological feedback (increase, no change, decrease, or no feedback) and stimulus order (presented first, second, third, or fourth within each feedback condition) as independent variables and heart rate change and attitudes as dependent variables. Additionally, there were the covaried factors of prior knowledge and also prior attitude about each nation stimulus, and the verbal label applied to each bogus feedback condition. METHOD Design The design is a 4 X 4 factorial with repeated measures on both factors. The first factor is a bogus physiological feedback factor consisting of nonveridical increase, decrease, or no change in physiological response, or no feedback at all. The second factor was an order factor, since each subject replicated each feedback condition four times. Hence, each subject recorded 16 observations in response to 16 different nation name stimuli. Combinations of nation with feedback condition were counterbalanced by means of four different Latin squares (four subject groups with five subjects per group), and order of presentation of the 16 nations was controlled by means of five different total randomizations (one subject in each subject group received each random order). The nation stimuli were chosen on the basis of responses to a questionnaire administered to each subject 1 week prior to the experimental session. This questionnaire was designed to ascertain subjects' attitudes and knowledge about a number of nations, and nation stimuli were chosen from this pretest to vary on the attitude and knowledge dimensions. Subjects Twenty-two university students volunteered as paid subjects to participate in a two-part "student opinion study." Two subjects were excluded from the analysis because of suspicion. The resultant sample consisted of 11 males and 9 females.
109
Apparatus Heart rate was measured by means of a Sanborn Model 60 twin-pen electrocardiograph (EKG). Bipolar limb leads (Lead II EKG) recorded the EKG. The bogus physiological feedback device was an EKG-GSR Simulator 2 that consisted of a large zero-center galvanometer and a speaker, which were operated remotely by the experimenter.3 The galvanometer indicated galvanic skin response (GSR) in either the positive or negative direction by a +100 to 0 to —100 scale. The heart rate consisted of electronically generated blips heard over the loudspeaker, which could be varied from approximately 45 to ISO beats per minute. Procedure The experiment was conducted in two parts separated by approximately 1 week. When subjects came to the first session, they were given a selfadministered questionnaire that included items designed to assess their attitude toward (very negative to very positive on a scale from 0 to 100, respectively, with SO as a midpoint), and extent of knowledge about (never heard of, scored 0, to great knowledge, scored 5) 41 alphabetically arranged nations, These nations were chosen on the basis of a pilot study to vary widely on both the knowledge and attitude dimensions, as well as to be distributed among all geographic areas of the world. In general, pilot study results held in the present study. The second session was arranged for approximately 1 week later. Upon arrival, the subject was seated in an empty office by the experimenter, who apologized because there would be a delay because of equipment trouble. After a reasonable wait, the subjects was first taken to the experimenter's control room and was shown the polygraph machine. It was explained that the delay was due to the polygraph, which was very old and working improperly. The experimenter "tore off" an artificially produced EKG and GSR paper tape record and took it with him as he ushered the subject back into the experimental room. Subjects were then told that the purpose of the study was to assess differences in opinions about different aspects (whether one was rating a nation, 1
These labels are consistent with Graham and Clifton's (1966) thesis that the accelerative component of heart rate is a defensive one. 2 The EKG-GSR Simulator was engineered and built by Charles Crane and Joseph Lewandowski. It electronically generated remarkably real-sounding audio heart rate pulses as well as having the visual galvanic skin response galvanometer. 8 Bogus feedback was given on both heart rate and galvanic skin response to maximize the strength of the manipulation. Both actual heart rate and galvanic skin response were recorded; however, because of a problem in the GSR recording technique, those data were not usable.
no
RICHARD A. DETWEILER AND MARK P. ZANNA
its leaders, or its people) of different countries, and that the country names would be presented on an automatically sequenced paper tape. The experimenter then told the subject that his advisor was also interested in how small stimuli can be and still cause physiological responses and that he wanted to use this opportunity "where sequential stimuli would be presented anyway" to also record physiological responses. At this point the meaning of EKG and GSR was explained, and the cognitive labels for the meaning of changes (increase, decrease, or no change) was given. The experimenter then continued: Now, recording this would have been pretty easy, except for the equipment trouble. Here's the tape the polygraph recorded on the last person [the artificially produced recording which had normal as well as obviously abnormal EKG and GSR patterns was shown to the subject] . . . I borrowed this apparatus here [referring to the bogus feedback device] from the biofeedback laboratories where they train people to control their heart rate and skin response by watching their own response on this equipment. . . . The fellows from the electronic shop wired it into the circuit so that I can use it to double-check the reading the polygraph gives so I'll know for sure when it's not working right . . . The feedback device is wired in on the other side of the wall where I can't see it ... Would you mind writing down for me what happens, and then I can compare afterward what you recorded with the paper tape? After subjects indicated that they would record what they presumed to be their actual physiological responses, the total procedure was described. First, they were to push a button that would advance the stimulus tape to a blank and turn on the physiological monitoring equipment. After about 10 seconds, the tape would automatically advance to a stimulus. The subject was to read the stimulus and then take note of any physiological changes, which he would then record on the appropriate sheet. The "meaning" (positive, neutral, or negative feelings) of the various physiological changes was again stressed. After this, the subject was to go on to the "real" purpose of this study and fill out the attitude measures. The subject was then told that the physiological feedback equipment would turn off automatically after about 2$ seconds had elapsed, and would remain off until the button was pushed again. Throughout, an effort was made to dissociate the physiological measurements from the purported purpose of the study. Any questions were then answered and the subjects were connected to the polygraph by means of skin electrodes. The experimenter finally added: If the monitoring equipment doesn't come on, don't worry about it—that just means that I have the wiring disconnected on the other side. I'm going to try to fix it while you're hooked up to it since I have to have heart rate and skin response signals coming into it to figure out what's wrong.
The experimenter then left the room, and after a 3-minute delay to allow heart rate to reach a resting level, the session began. Prior to the 16 experimental trials, 2 credibility trials occurred. On these trials, the bogus feedback was given to be consistent with the subject's attitudes as expressed on the prerating questionnaire. These credibility-trial nation stimuli were chosen individually for each subject; they were one very liked and one very disliked nation that were not being used in the experimental trials. During the 16 experimental trials each subject heard his or her heart rate and saw his or her skin responses (in random order) increase on four trials, decrease on four trials, and not change on four trials. On the remaining four trials, the equipment did not come on at all. The bogus heart rate baseline was set independently for each subject to correspond with actual heart rate as measured by the Sanborn recorder. Changes in bogus heart rate consisted of an increase or decrease of approximately 15 beats per minute. If a subject did not indicate that his or her heart rate increased (or decreased, as the case might be), the amount of increase (or decrease) was partially corrected by increasing (or decreasing) the bogus heart rate feedback until a change was indicated in the desired direction. The bogus GSR baseline was zero for all subjects and increased or decreased by 65 to 85 points on a 100-point scale. In the neutral feedback condition the needle remained within 5 points of zero. After the final trial, debriefing for suspicion was undertaken, followed by an explanation of the true nature of the experiment. Subsequent questions were answered, and the importance of secrecy concerning the experiment was stressed.
Dependent Variables Heart rate. The measure of change in heart rate was adapted from that advocated by Beecroft (1966). The heart rate before each stimulus was ascertained by calculating the mean interbeat interval (IBI) of the last three beats prior to stimulus presentation. The after heart rate was determined by calculating the mean IBI of the three beats beginning with the beat closest to the fifth second after stimulus onset.4 This time lag was used because heart rate latency is (according to studies 4 Analyses using the 2- to 5-second interval as the post heart rate measure gave results similar to those reported here. An additional examination of the heart rate response curve was undertaken by randomly selecting one trial per subject and calculating a mean response curve. These data indicated a principally monophasic deceleration, with a possible diphasic effect in which deceleration occurred for the first two beats, followed by acceleration on the third beat, followed immediately by greater deceleration. Maximum deceleration was reached by about the sixth beat (at about 5 seconds after the stimulus).
PHYSIOLOGICAL MEDIATION OF ATTITUDINAL RESPONSES cited by Beecroft) about 2 seconds, reaching its peak at about 5 to 7 seconds. The actual heart rate measure employed was the change in mean heart rate IBI from before to after each stimulus onset. Longer recording intervals were not used, since diphasic heart rate changes can make dependent measures based on the mean change of longer intervals invalid indicators of heart rate change (see Johnson & Lubin, 1972). Prior to the first trial, about 3 minutes were allowed to elapse from the time the experimenter left the subject until the first stimulus was presented, to allow the heart rate to reach a resting level. After that time, the pace of the trials was in part determined by the subject who pushed a button to indicate readiness for the next trial. The average time between the delivery of the various bogus feedback manipulations was approximately 3 minutes. Attitude. The measure of attitude consisted of 20 adjectives, each of which was responded to by placing a mark on a line to indicate the degree to which that particular trait characterized the nation stimulus. The mark was then coded into a value with a ruler on a 100-point scale. The 20 adjectives in fact consisted of 10 polar opposite pairs as follows: unintelligent-intelligent, unpredictable-predictable, trustworthy-untrustworthy, cruel-kind, modest-arrogant, lazy-hardworking, friendly-unfriendly, generous-selfish, rude-polite, and peace-orientedwar-oriented. The positive traits were scored on a scale of 0 to +100, with +100 indicating complete possession. The negative traits were scored on a scale of 0 to —100, with —100 indicating complete possession. The main attitude measure was created by averaging the responses to these scales. Thus, if a subject felt that a nation possessed the 10 positive traits and did not possess the 10 negative traits he or she received a mean score of +50; if a subject felt the exact opposite, he or she would receive a mean score of —50. TABLE 1 ANALYSES OF VARIANCE or MEAN ATTITUDE AND HEART RATE CHANGE Source
df
MS
Dependent measure: attitude Bogus feedback Order Feedback X Order Residual
3 3 9 285
15.94 26.88 20.22 44.08
