Perceptual and Motor Skills, 1977,45, 75 1-756. @ Perceptual and Motor Skills 1977

PUPILLARY RESPONSES AS A MEASURE OF AITITUDES ABOUT ALCOHOLIC BEVERAGES SUE BEALL1 Texas A. & M. University Summary.-Pupillary and verbal responses of 3 9 adult subjects were not significantly associated though mean pupillary responses while viewing slides of a seascape, an automobile accident, and a control slide were significantly different. There was a positive relation between stated dislike of the accident scene and pupillary constriction. Pupillary responses and Bcll Alcohol Scale scores correlated -.42.

Pupillographic measurement in relation to attitudes began in the early 1960s. The early studies showed the pupil of the eye to be an indicator of various neural responses. Pupil size was shown to be an indicator of interest in certain visual stimuli (Hess & Polt, 1960). Attitudes toward sexuality were measured by pupil dilation and constriction (Hess, 1965; Hess, Seltzer, & Shlien, 1965). Pupillary responses were also used as an indicator of taste differences in beverages (Hess & Polt, 1966). Other research utilizing the same methodology and instrumentation did not show similar relationships between pupil dilation and constriction with attitudes about racial acceptance (Woodmansee, 1970). Since the research completed by Hess and Woodmansee differed in results and conclusions about the validity of pupillography in measuring attitudes, this study was initiated to replicate the methodology and attempt to establish relationships between pupillary responses and attitude involvement. In the present study an effort was made to determine the relationships between pupillary responses (dilation/constriction) and attitudes about alcoholic beverages.

METHOD The subjects were 39 female students from the Texas Woman's University during the Spring semester of 1975. They were divided into two groups, 19 non-drinkers and 20 social drinkers on the basis of their scores on an Alcohol Attitude Scale developed by Bell ( 1955 ) . The scale was reliable (0.92) and produced significantly different scores for abstainers and non-abstainers ( p = .01). The pupillographic measurement was made for each subject in two sessions, pre- and posttests 1 week apart. The basic pupillographic technique followed by both Hess and Woodmansee in each of their reports was utilized with only minor variations in equipment and protocol. The process included filming the left eye with 16-mm. high speed infra-red black and white film (Kodak 2481, Estar base) while the subject viewed a series of color slides. 'Department of Health and Physical Education, Texas A&M University, College Station, Texas 77843.

752

S. BEALL

Apparatus and Stimuli The camera used to record the film data was the Action-Master/ZOO, Model 16 mm-lVN, manufactured by Photo-Sonics, Incorporated. A 75-mm. singlereflex lens was attached to the camera with a series of "C" mount extension rings to allow for dose-up focusing of the eye. A support apparatus was used to adjust camera height and horizontal location in front of the eye, situate the head of the subject with a stationary head rest and adjustable chin rest, and provide a light source for the eye. A drawing of the apparatus is shown in Fig. 1.

FIG. 1. Drawing of apparatus with a subject's head in position

A 25-w bulb, housed in a cylindrical reflector on the head rest apparatus, provided direct light to the left eye for photographing. The light was filtered by a 3- X 3-in. NO. 87 Wrattan Gelatin Filter. The light could also be adjusted horizontally and vertically for correct positioning. The visual stimuli utilized in this research were three slides of alcoholic beverages, a neutral scene (seascape), and a negative scene (automobile accident). The three slides of alcoholic beverages included: a glass of wine, a mug of beer, and a glass of bourbon with the bottle in the background. Control slides of two blue and yellow concentric circles were shown between stimulus slides to give the pupil a chance to return to a base level of response after each stimulus. Slides were projected onto a rear projection screen set at a distance of 192 cm. in front of the subject at an 18' angle above eye level. Two Kodak Carousel Ektagraphic Projectors and a Model 2 Dissolve Control Unit were used to project the slides in a continuous sequence at 10-sec. intervals. The continuous lighting of the screen with stimulus slides and control slides prevented light changes from effecting pupillary responses. The amount of light emitting from the screen was maintained at 2.5 ft-c. for each slide by adding shaded pieces of clear plastic to slides with bright spots above the 2.5-fr-C. level.

PUPILLARY RESPONSE AND A?TITUDE

753

Procedare Each subject answered the Alcohol Attitude Scale prior to the first filming session. The following statement was read to each subject prior to entering the filming room: "Respond with Yes if you would like to be a part of the scene, or respond with No if you would not like to be a part of the scene." The subject was seated in front of the apparatus and asked to place her chin and forehead in the head rest. Adjustments were made for comfort and proper lighting of the left eye. While the subject focused on a spot in the center of the screen a boresight tool was used to focus the camera lens on the pupil of the eye. It was then replaced with the camera's film magazine and the room was darkened. After 1 min. which allowed the subject's eyes to adjust to the darkness, the camera and slide sequence were started by the investigator from a control desk. At the completion of the first filming session each subject was asked to return for a second filming in 1 wk. Each session provided 40 frames of film data for each of the five stimulus slides and four control slides shown. This was accomplished by setting the camera's pulsation device at four frames per second for film exposure and by setting the timing device on the camera and the dissolve unit for 10-sec. periods. The innermost 20 frames for each set of 40 were analyzed on a Vanguard Film Analyzer, which magnified each frame 23 X its natural size. The first and last 10 frames of each set were omitted to allow for possible error due to pupillary adjustment to slide changes. Thus the innermost 20 frames of each set represented the most accurate pupillary response for each stimulus slide. Each of these frames was measured in inches on a horizontal diameter of the pupil. The 20 measurements were totaled and averaged for each slide, giving a mean pupil size for each stimulus slide. RESULTS The average pupillary response while viewing the seascape (neutral scene), the automobile accident (negative scene), and a control slide was analyzed by analysis of variance with repeated measures. The mean pupillary responses on the three slides were 2.37, 2.11, and 2.28 in., respectively. The SDs for each of the three slides were .42, .45, and .39, respectively. The resulting F ratio of 37.16 ( 9 > 0.01) indicates that the repeated measures of the three different kinds of visual stimuli were significantly different for the 3 9 subjects. Table 1 presents chi-square information on verbal response and pupillary response to the seascape and accident scene. There is some indication that the stated preference of like or dislike is not dependent upon pupillary response to a seascape or neutral scene. However, there is a positive relationship between the stated preference of disliking the accident or negative scene and pupillary constriction. Table 2 shows a tally of the corresponding pupil response and verbal re-

S. BEALL

TABLE 1 CHI-SQUAREON VERBAL RESPONSEAND PUPILLARYRESPONSE TO SCENESOF A SEASCAPE AND A N AUTOMOBILE ACCIDENT Verbal Response Like f

Pupillary Response Dilation Constriction Total 25

.015

Xa

Dislike f

2

.566

x'

X9

Note.-At

P.86

12 .033 0 .022

Verbal Response Like f

37

Xa

Dislike f

2

xa

= 636

Pupillary Response Dilation Constriction Total 0 8.64 1 0

0

.23 38 0 x' = 8.87

0

39

= 3.8.

sponse for each of the 39 subjects. For each stimulus slide separately chi-square technique was applied to determine the independence of verbal and pup~llary responses. A chi-square on each of the alcoholic beverage slides indicated that pupillary responses and verbal responses to the three stimuli were not dependent on each other. The chi-square computed for the wine stimulus slide was 1.93, for the beer slide the value was 2.45, and for the liquor slide 1.15. None of these three met the tabled value of 3.8 ( p = 0.05). TABLE 2

Wine Dilate Constrict Like Dislike

13

2

10

14

Beer

Dilate Constrict 8 15

2 14

Liquor Dilate Constrict 6 5 10

18

The Bell Alcohol Attitude Scale scores and the pupillary responses for the

39 subjects were correlated -.42, using the Pearson product-moment technique. This correlation indicates that as attitude scale scores became higher toward rejection of alcohol, the pupillary responses tended to become smaller or more constricted. This correlation of -.42 is a moderate but substantial relationship ( p = 0.05 ) . The pupillographic technique followed in this research was reliable ( r = .916). Hess and Woodmansee had also established the reliability of this technique. Hess utilized the Friedman two-way analysis of variance to show that the difference in the mean ranks of five orange beverages was significant at the .002 level. Woodmansee'concluded that the pupillographic technique was reliable in measuring the affective dimension of attitudes but not positive attitudes versus negative attitudes. In Table 3 a discrimination between social drinkers and non-drinkers is indicated by the percentage of dilation or constriction. The positive percentage

755

PUPILLARY RESPONSE AND ATTITUDE

of dilation on each of the stimuli for the social drinkers indicates a larger pupil size when they viewed the stimulus than when they viewed the control. A negative percentage indicates a smaller mean pupil size during stimulus viewing than when viewing the control. It may also be noted in Table 3 that dilation and constriction seem to be consistent for both groups over the pre- and posttest measurements. Dilation for the slide scenes of alcoholic beverages was most often noted for the non-drinkers. TABLE 3 PUPIL-SIZE INCREASEOR DECREASE WHENCOMPARING STIMULI To CONTROLS EXPRESSEDIN PERCENT OF TOTALS FOR m0 TRIALS Groups Social Drinkers Pretest Posttest Non-drinkers Pretest Posttest

Seascape (Neutral)

Wine

Slides Beer

03.42 07.66

07.23 10.07

-01.50 02.10

-04.64 -00.09

Liquor

Accident (Negative)

07.73 10.15

06.93 05.74

-05.16 -07.83

-01.42 01.14

-08.28 -04.17

-14.05 -14.24

Since the repeated measures of pupillary responses to a neutral scene, a negative scene, and a control slide were significantly different for these 39 subjects, it seems that differences are dependent upon personal preference for or rejection of the objects or scenes viewed. N o relationship seems to exist between neutral scenes and pupil dilation or constriction but verbal expression of dislike does seem to be related to pupillary constriction when viewing a negative scene such as an automobile accident. These data suggest that disliking is related to pupillary constriction, a finding which supports conclusions of Hess ( 1965) .

Pupillary responses of a l l subjects were not dependent upon verbal responses to the alcoholic beverage scenes. Personal preference expressed as dislike of the alcoholic beverage scenes was much heavier for non-drinkers than their pupillary response implied. This discrepancy between verbal response and pupillaty response may indicate that pupillographic measurement of attitude gives a more complete description of the attitude set because it allows for gradations of measurement within the dilation or constriction categories. Attitude scales or questionnaires which elicit Yes/No responses do not provide such descriptions. Since non-drinkers did not exhibit a strong negative response (constriction) to the alcoholic beverage slides, it seems that alcoholic beverages ate not repulsive to view even though the individuals say they would not want to be

a part of the alcoholic beverage scene. It may be noted in Table 3 that the percentage of constriction for non-drinkers (-00.09) on the posttest as they viewed the wine slide was only slightly different than their response to the control slide which preceded it. For the same group there was also dilation (01.14) when they viewed the beer slide on the posttest. The greatest difference between social drinkers' and non-drinkers' responses seemed to appear when they viewed the liquor slide. The dilation noted on both trials for social drinkers was greater for beer and wine than for liquor. Thus one might conclude that for these social drinkers and non-drinkers beer and wine are more acceptable forms of beverage alcohol than is liquor. Correlation of the pupillographic measurement with the Bell Alcohol Attitude Scale measurements was not as high as was envisioned. It must be considered however that the attitude scale was devised in 1955, and the instrument may not have been as valid for use in 1975 as some 20 yr. earlier. Since the scores on the scale were computed for all "agree" statements the Yes/No categories limited the perceptivity of the measurement. It is recommended that pupillographic measurement of attitude be validated by correlation with another physiological measurement such as galvanic skin response or with a written instrument such as the semantic differential. REFERENCES BELL,S. E. Attitudes to drinking alcoholic beverages: an alcohol attitude scale. Unpublished M.S. thesis, Univer. of Toronto, 1955. Hass, E. H. Attitude and pupil size. Scientific American, 1965, 62, 46-54. HBSS,E. H., & POLT,J. M. Changes in pupil size as a measure of taste differences. Percept& and Motor Skills, 1966, 23, 45 1-455. Hass, E. H., SELTZER, A. L., & SHLIEN, J. M. Pupil response of hetero- and homosexual males to pictures of men and women. Journal of Abnormal Psychology, 1965, 70, 165-168. WOODMANSEE, J. J. The pu il response as a measure of social attitudes. In G. F. Sommers (Ed.), ~ t t i r u 2rneasurernent. Chicago: Rand McNally, 1370. Pp. 392395.

Accepted August 10, 1977.

Pupillary responses as a measure of attitudes about alcoholic beverages.

Perceptual and Motor Skills, 1977,45, 75 1-756. @ Perceptual and Motor Skills 1977 PUPILLARY RESPONSES AS A MEASURE OF AITITUDES ABOUT ALCOHOLIC BEVE...
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