Perceptual and Motor Shills, 1978,47, 779-782. @ Perceptual and Motor Skills 1978
PUPILLARY SIZE AS AN INDICATOR OF PREFERENCE I N
HUMOR1
J. H.WAGONER AND C. B. SULLENBERGER United Stares Air Force Academy Summmy.-The effects of simple cartoons on pupil size were examined. Each of the 11 subjects was presented three cartoons for 10-sec. with a S-sec. control period ,between the presentations. All subjects received the same task condition. When the presentation was complete, each subject ranked the three cartoons to show their preference on the dimension of humor. The data produced significant correlation between the rank order and the pupillary dilation. Means of pupil size for the cartoons were also significantly different from control means.
Since Hess and Polt's (1960) early study of pupil size and ongoing mental activity of interest, emotion, thought processes and attitudes, research about pupillary reaction has increased. Many of the studies concerning cognitive demand on pupil size (Hess & Polt, 1964; Kahneman & Beatty, 1966; Schaefer, Ferguson, Klein, & Rawson, 1968; Chapman, Chapman, & Brelje, 1969; Poock, 1973) have been consistent in showing that simple problem solving, memory load, and certain cognitive acts correlate positively with pupil dilation. Other research was expanded into testing verbal preferences in relation to pupil dilation. Hess (1965) found that individual preference of five orange beverages could be obtained by observing the amount of pupil dilation while sipping the beverages. For pictures of food a high positive correlation of the rating of preferred food and pupil dilation (Hess & Polt, 1966) was noted. Sexual preference and stimulation was also positively correlated with the pupil dilation (Hamel, 1974; Hess, Seltzer, & Schlien, 1965; Simons, 1967). Further data indicated that dilation was associated with pleasant stimuli and constriction with unpleasant stimuli (Fredericks, 1770; Fredericks & Groves, 1771). Studies were expanded further into political preferences. Hess (1965) showed a low positive correlation between the subjects' verbal responses and pupillary dilation in political preference of either Johnson or Goldwater. When political figures were more differentiated in their political viewpoints, pupil size served as a good indicator of preference (Barlow, 1969). Generally, however, results on social attitudes have not been conclusive. Personal preference in ratings and verbal responses to photographs have been more conclusive. Pupil size is positively correlated with ratings of photographs on a pleasant-unpleasant continuum (Barlow, 1970). The study presented here investigates changes 'in pupil size in relation to different levels of humor as judged by subjects' preferences. This involves two hypotheses. First, that pupils dilate while looking at stimuli seen as humorous and second, that judged humor is associated with an increase in pupil size. The basis for these questions is similar to the previous studies. The reflex is con'The views expressed by this paper are not those of the United States Air Force.
780
J. H. WAGONER
ei C. B.
SULLENBERGER
trolled by the autonomic nervous system, either parasympathetic or sympathetic. The data provide a basis for the inference that in the sympathetic system there is a response to emotional states as well as cognitive load. Since preferences in sexual, pleasant-unpleasant, and some social attitudes are related to pupillary size, it seems valid to assume that humor is also correlated with pupillary size. METHOD Apparatz~s T h e apparatus for recording pupil size was a Space Science, Inc., TV pupilometer. The mechanical stand was made by Bausch and Lomb, Cat. No. 71-61-40. T h e camera was a Sony Video-Camera. An independent infrared light was used to illuminate the eye from a distance of approximately 5 in. T h e T V monitor, Mod. 800.3, another Space Science, Inc. product, was used to focus and center the eye. The pupilometer was connected to a Brush Mark 260 recorder made by Gould. T h e recorder measured the D.C.milliamperes from the TV monitor by deflections of graphical form on the recorder. For each milliampere change there was a millimeter change in the pupil size. All deflections of the recorder were due to pupillary changes and not noise interference. The subjects were studied i n a walled off section of a room with four 60-w fluorescent bulbs for lighting. Three cartoons of "Dennis the Menace" were mounted o n white cardboard. T h e cartoons were from the month of May, 1972. Each cartoon was a single picture with a caption. Subjects Eleven male students aged 19 to 21 yr. served as subjects in the experiment. All the volunteers were cadets in the United States Air Force Academy. All subjects had medium colored irises and focused on a target 2 ft. away. None wore glasses since the pupilometer functioned only with an unobstructed view of the eye. Design and Procedure All 11 subjects were given the same task condition. Each subject was presented the same random order of the three cartoons. Each cartoon was presented 2 ft. from the subject's eye for 1 0 sec. A 5-sec. control period followed each cartoon during which the subject had no stimulus. After the subject had completed the presentation of cartoons, all the cartoons were put in front of him. T h e subject was given a 3-in. X 5-in. card to rank order the cartoons on, 1 being the funniest and 3 the least funny.
RESULTS Pupil size was averaged for dilation values of all subjects for every 2 sec. These data are presented in Fig. 1. The curve is arranged so that each 10-sec. cartoon presentation is separated by a 5-sec. control period. The points on the curve are each based on 11 measurements of pupil size (one for each of the 11 subjects). The mean pupillary dilation of all the experimental values was ,6018 rnm, while that of control values was .2969 mm. By Student's t the means were significantly different ( t = 5.82, df = 10, p < .0005). With the presentation of the cartoons, there was an increase in pupil diameter in almost every
PUPILLARY SIZE AND HUMOR
781
case. The mean of the greatest dilation values during the experimental periods was .4136 mm. Again they were significantly different (t = 4.11, df = 10, p < .005). The dilation which occurred with the presentation of each stimulus lasted throughout the rest of each experimental period. There was a constriction back to a smaller diameter after the removal of the stimulus. The cartoons were put in rank order according to how much dilation they elicited for each subject. First, means were calculated for each cartoon presented for each subject. Then the carcoon which elicited the most dilation for a subject was assigned a score of 1, etc. These dilation scores were compared with the scores which the subjects had given in their rank ordering of the cartoons. Using the chi-square test of independence and the Cramer's statistic, the subjects' ratings of the cartoons and their pupil dilations gave the same idormation ( 6 cells, df = 2, x2 = 13.66 and N = 33, C, = .643). The cartoons which the subjects picked as the funniest also elicited the largest pupil dilations.
"dm,, , , , , , , , , , , ,
FIG. 1. Change in pupil size over time for subjects while observing "Dennis the Menace" cartoons
#
,,,,,I
6
1 0 1 4 u I 2 2 2 6 3 0 3 4 3 8 4 2
z
3
2
TIME IN SECONDS
The results indicate that the subjects' pupils dilate significantly in response to the stimuli of "Dennis the Menace" cartoons as compared to the neutral control. The first hypothesis is supported. The marked degree of significance of cartoon means of pupil size from control means can be observed by the statistics ( p < .0005) and-changes on the graph in Fig. 1. This difference is the most solid finding in this study. The results also indicate that a person's rank-order preference of the cartoons can be predicted by the amount of pupillary dilation. Thus judged humor seems to be associated with the amount of increase in pupil size. Even with this moderate correlation about half of the subjects stated they had difficulty rating at least one of the cartoons. A possible explanation for this minor contradiction may be that cognitive weighing of humorousness is inexact especially compared with accurate measurement of pupil diameter. As an implication, measurement of pupil size may be as accurate in predicting personal preference in humor even when individual judgments are increasingly difficult. In summary, changes in pupil size in relation to judged preference in three simple cartoons were examined. Eleven subjects participated in the presentation
782
J. H. WAGONER
&
C. B. SULLENBERGER
and rank ordering of the cartoons on a scale of humorousness. The most clear finding indicated that pupils dilate when subjects view cartoons. Also, cartoons rated as funniest significantly elicited the larger pupil dilation. REFERENCES BARLOW, J. D. Pupillary size as an index of preference in political candidates. Perceptual and Motor Skills, 1969, 28, 587-590. BARLOW, J. D. Pupillary size as an index of preference. Perceptual and Motor Skills, 197C, 331-336. CHAPMAN,L. J., CHAPMAN,J. P., & BRELJE, T. Influence of the ex rimenter on pupillary dilation to sexually provocative pictures. Journal of ~ E o r m a lfiychology, 1969, 74, 396-400. FREDERICKS. R. S. Repression-sensitization and pupillary response to pleasant and unpleasant stimuli. Dissertation Abstracts International, 1970, 31 (5-8), 2982. FREDERICKS, R. S., & GROVES, M. H. Pupil change and stimulus pleasantness. Psoceedingr of Annual Convention of the American Psychological Association, 1971, G(Pt. l ) , 371-372. HAMEL, R. F. Female subjective and pupillary reaction to nude male and female figures. Journd of Psychology, 1974, 87, 171-175. HESS,E. H. Attitude and pupil size. Scientific American, 1965, 212, 46-54. HESS,E. H., & POLT, J. M. Pupil size as related to interest value of visual stimuli. Science, 1960, 132, 349-350. HESS,E. H., & POLT,J. M. Pupil size in relation to mental activity during simple problem-solving. Science, 1964, 143, 1190-1192. HESS,E. H., & POLT,J. M. Changes in pupil size as a measure of taste differences. Perceptual and Motor Skills, 1966, 23, 45 1-455. HESS,E. H., SELTZER,A. L., & SHLIEN,J. M. Pupil response of heterosexual and homosexual males to pictures of men and women: a pilot study. Journal of Abrwrmul Psychology, 1965, 70, 165-168. KAHNEMAN, D., & B E A ~J., Pupil diameter and load on memory. Science, 1966, 154, 1583-1585. POOCK, G . K. Information processing vs pupil diameter. Perceptual and Motor Skills, 1973. 37, 1000-1002. SCHAEPER, T., FERGUSON, J. B., KLBIN, J. A., & RAWSON,E. B. Pupillary responses during mental activity. Psychonomic Science, 1968, 12, 137-138. SIMONS, T. M. Pupillary response of male and female subjects to upillary differences in male and female p i m r e stimuli. Perception and ~syciophyrics, 1967, 2, 553-555. Accepted August 24, 1978.
PUPILLARY SIZE AS AN INDICATOR OF PREFERENCE I N
HUMOR1
J. H.WAGONER AND C. B. SULLENBERGER United Stares Air Force Academy Summmy.-The effects of simple cartoons on pupil size were examined. Each of the 11 subjects was presented three cartoons for 10-sec. with a S-sec. control period ,between the presentations. All subjects received the same task condition. When the presentation was complete, each subject ranked the three cartoons to show their preference on the dimension of humor. The data produced significant correlation between the rank order and the pupillary dilation. Means of pupil size for the cartoons were also significantly different from control means.
Since Hess and Polt's (1960) early study of pupil size and ongoing mental activity of interest, emotion, thought processes and attitudes, research about pupillary reaction has increased. Many of the studies concerning cognitive demand on pupil size (Hess & Polt, 1964; Kahneman & Beatty, 1966; Schaefer, Ferguson, Klein, & Rawson, 1968; Chapman, Chapman, & Brelje, 1969; Poock, 1973) have been consistent in showing that simple problem solving, memory load, and certain cognitive acts correlate positively with pupil dilation. Other research was expanded into testing verbal preferences in relation to pupil dilation. Hess (1965) found that individual preference of five orange beverages could be obtained by observing the amount of pupil dilation while sipping the beverages. For pictures of food a high positive correlation of the rating of preferred food and pupil dilation (Hess & Polt, 1966) was noted. Sexual preference and stimulation was also positively correlated with the pupil dilation (Hamel, 1974; Hess, Seltzer, & Schlien, 1965; Simons, 1967). Further data indicated that dilation was associated with pleasant stimuli and constriction with unpleasant stimuli (Fredericks, 1770; Fredericks & Groves, 1771). Studies were expanded further into political preferences. Hess (1965) showed a low positive correlation between the subjects' verbal responses and pupillary dilation in political preference of either Johnson or Goldwater. When political figures were more differentiated in their political viewpoints, pupil size served as a good indicator of preference (Barlow, 1969). Generally, however, results on social attitudes have not been conclusive. Personal preference in ratings and verbal responses to photographs have been more conclusive. Pupil size is positively correlated with ratings of photographs on a pleasant-unpleasant continuum (Barlow, 1970). The study presented here investigates changes 'in pupil size in relation to different levels of humor as judged by subjects' preferences. This involves two hypotheses. First, that pupils dilate while looking at stimuli seen as humorous and second, that judged humor is associated with an increase in pupil size. The basis for these questions is similar to the previous studies. The reflex is con'The views expressed by this paper are not those of the United States Air Force.
780
J. H. WAGONER
ei C. B.
SULLENBERGER
trolled by the autonomic nervous system, either parasympathetic or sympathetic. The data provide a basis for the inference that in the sympathetic system there is a response to emotional states as well as cognitive load. Since preferences in sexual, pleasant-unpleasant, and some social attitudes are related to pupillary size, it seems valid to assume that humor is also correlated with pupillary size. METHOD Apparatz~s T h e apparatus for recording pupil size was a Space Science, Inc., TV pupilometer. The mechanical stand was made by Bausch and Lomb, Cat. No. 71-61-40. T h e camera was a Sony Video-Camera. An independent infrared light was used to illuminate the eye from a distance of approximately 5 in. T h e T V monitor, Mod. 800.3, another Space Science, Inc. product, was used to focus and center the eye. The pupilometer was connected to a Brush Mark 260 recorder made by Gould. T h e recorder measured the D.C.milliamperes from the TV monitor by deflections of graphical form on the recorder. For each milliampere change there was a millimeter change in the pupil size. All deflections of the recorder were due to pupillary changes and not noise interference. The subjects were studied i n a walled off section of a room with four 60-w fluorescent bulbs for lighting. Three cartoons of "Dennis the Menace" were mounted o n white cardboard. T h e cartoons were from the month of May, 1972. Each cartoon was a single picture with a caption. Subjects Eleven male students aged 19 to 21 yr. served as subjects in the experiment. All the volunteers were cadets in the United States Air Force Academy. All subjects had medium colored irises and focused on a target 2 ft. away. None wore glasses since the pupilometer functioned only with an unobstructed view of the eye. Design and Procedure All 11 subjects were given the same task condition. Each subject was presented the same random order of the three cartoons. Each cartoon was presented 2 ft. from the subject's eye for 1 0 sec. A 5-sec. control period followed each cartoon during which the subject had no stimulus. After the subject had completed the presentation of cartoons, all the cartoons were put in front of him. T h e subject was given a 3-in. X 5-in. card to rank order the cartoons on, 1 being the funniest and 3 the least funny.
RESULTS Pupil size was averaged for dilation values of all subjects for every 2 sec. These data are presented in Fig. 1. The curve is arranged so that each 10-sec. cartoon presentation is separated by a 5-sec. control period. The points on the curve are each based on 11 measurements of pupil size (one for each of the 11 subjects). The mean pupillary dilation of all the experimental values was ,6018 rnm, while that of control values was .2969 mm. By Student's t the means were significantly different ( t = 5.82, df = 10, p < .0005). With the presentation of the cartoons, there was an increase in pupil diameter in almost every
PUPILLARY SIZE AND HUMOR
781
case. The mean of the greatest dilation values during the experimental periods was .4136 mm. Again they were significantly different (t = 4.11, df = 10, p < .005). The dilation which occurred with the presentation of each stimulus lasted throughout the rest of each experimental period. There was a constriction back to a smaller diameter after the removal of the stimulus. The cartoons were put in rank order according to how much dilation they elicited for each subject. First, means were calculated for each cartoon presented for each subject. Then the carcoon which elicited the most dilation for a subject was assigned a score of 1, etc. These dilation scores were compared with the scores which the subjects had given in their rank ordering of the cartoons. Using the chi-square test of independence and the Cramer's statistic, the subjects' ratings of the cartoons and their pupil dilations gave the same idormation ( 6 cells, df = 2, x2 = 13.66 and N = 33, C, = .643). The cartoons which the subjects picked as the funniest also elicited the largest pupil dilations.
"dm,, , , , , , , , , , , ,
FIG. 1. Change in pupil size over time for subjects while observing "Dennis the Menace" cartoons
#
,,,,,I
6
1 0 1 4 u I 2 2 2 6 3 0 3 4 3 8 4 2
z
3
2
TIME IN SECONDS
The results indicate that the subjects' pupils dilate significantly in response to the stimuli of "Dennis the Menace" cartoons as compared to the neutral control. The first hypothesis is supported. The marked degree of significance of cartoon means of pupil size from control means can be observed by the statistics ( p < .0005) and-changes on the graph in Fig. 1. This difference is the most solid finding in this study. The results also indicate that a person's rank-order preference of the cartoons can be predicted by the amount of pupillary dilation. Thus judged humor seems to be associated with the amount of increase in pupil size. Even with this moderate correlation about half of the subjects stated they had difficulty rating at least one of the cartoons. A possible explanation for this minor contradiction may be that cognitive weighing of humorousness is inexact especially compared with accurate measurement of pupil diameter. As an implication, measurement of pupil size may be as accurate in predicting personal preference in humor even when individual judgments are increasingly difficult. In summary, changes in pupil size in relation to judged preference in three simple cartoons were examined. Eleven subjects participated in the presentation
782
J. H. WAGONER
&
C. B. SULLENBERGER
and rank ordering of the cartoons on a scale of humorousness. The most clear finding indicated that pupils dilate when subjects view cartoons. Also, cartoons rated as funniest significantly elicited the larger pupil dilation. REFERENCES BARLOW, J. D. Pupillary size as an index of preference in political candidates. Perceptual and Motor Skills, 1969, 28, 587-590. BARLOW, J. D. Pupillary size as an index of preference. Perceptual and Motor Skills, 197C, 331-336. CHAPMAN,L. J., CHAPMAN,J. P., & BRELJE, T. Influence of the ex rimenter on pupillary dilation to sexually provocative pictures. Journal of ~ E o r m a lfiychology, 1969, 74, 396-400. FREDERICKS. R. S. Repression-sensitization and pupillary response to pleasant and unpleasant stimuli. Dissertation Abstracts International, 1970, 31 (5-8), 2982. FREDERICKS, R. S., & GROVES, M. H. Pupil change and stimulus pleasantness. Psoceedingr of Annual Convention of the American Psychological Association, 1971, G(Pt. l ) , 371-372. HAMEL, R. F. Female subjective and pupillary reaction to nude male and female figures. Journd of Psychology, 1974, 87, 171-175. HESS,E. H. Attitude and pupil size. Scientific American, 1965, 212, 46-54. HESS,E. H., & POLT, J. M. Pupil size as related to interest value of visual stimuli. Science, 1960, 132, 349-350. HESS,E. H., & POLT,J. M. Pupil size in relation to mental activity during simple problem-solving. Science, 1964, 143, 1190-1192. HESS,E. H., & POLT,J. M. Changes in pupil size as a measure of taste differences. Perceptual and Motor Skills, 1966, 23, 45 1-455. HESS,E. H., SELTZER,A. L., & SHLIEN,J. M. Pupil response of heterosexual and homosexual males to pictures of men and women: a pilot study. Journal of Abrwrmul Psychology, 1965, 70, 165-168. KAHNEMAN, D., & B E A ~J., Pupil diameter and load on memory. Science, 1966, 154, 1583-1585. POOCK, G . K. Information processing vs pupil diameter. Perceptual and Motor Skills, 1973. 37, 1000-1002. SCHAEPER, T., FERGUSON, J. B., KLBIN, J. A., & RAWSON,E. B. Pupillary responses during mental activity. Psychonomic Science, 1968, 12, 137-138. SIMONS, T. M. Pupillary response of male and female subjects to upillary differences in male and female p i m r e stimuli. Perception and ~syciophyrics, 1967, 2, 553-555. Accepted August 24, 1978.
