PUPIL SIZE, AFFECT AND EXPOSURE FREQUENCY

Abstract

Four investigations of the affect-pupil size relationship are reported here as attempts to test Hess's (1965) attraction-dilation and aversion-constriction hypotheses. In the first two studies, no evidence was found for a relationship between pupil size and frequency of exposure to a stimulus as defined by Zajonc (1968). However, it was observed that the stronger a stimulus was rated in terms of affect (like-dislike), whether positive or negative, the larger the pupil size. Pupil size at the neutral point was not smallest, as expected, but was elevated, relative to the points adjacent to it. Two additional studies, using a pseudo task which induced feelings of success or failure, confirmed the previous findings. A positive relationship was found between pupil size and affect intensity, and again, elevated pupil size at the neutral points. There was no evidence of constriction to any stimulus, positive or negative, in any of the four studies. It was concluded that pupil size is linearly related to the intensity continuum of affect and curvilinearly related to its valence (positive-negative) continuum.