Portrait Hemispheric Laterality Measured Using Pupil Diameter and Aesthetic Judgments

Eckhard Hess’s claim that pupils dilate to pleasant images and constrict to unpleasant images was confounded because of inconsistent contrasts and luminances across his images. Building upon the work of Powell and Schirillo (2011) that explored multiple portraits by Rembrandt, we offer a new and promising methodology that overcomes this limitation. We presented leftwardor rightward-facing female and male portraits by 12 artists from various epochs to observers in either their original or mirror-reversed positions. Simultaneously, we asked observers to report how (dis)pleasing they found each image while measuring their pupil size. We found that pupil diameter was a function of arousal only while viewing male portraits. That is, for male images rated both low and high in pleasantness, larger pupil diameters were obtained. We postulate that our findings may be the result of the perceived dominance of males and how hemispheric laterality may drive emotional expression.