Hemispheric laterality measured in Rembrandt's portraits using pupil diameter and aesthetic verbal judgements

Abstract

Eckhard Hess claimed that pupils dilate to pleasant images and constrict to unpleasant images. However, his work was confounded since his image's luminances and contrasts across conditions were inconsistent. We overcome this limitation and suggest a new, promising methodology for research in this area. We presented rightward or leftward facing male and female portraits by Rembrandt to observers in either their original or mirror-reversed position. Since emotional content may be expressed differently on each side of the face, we used Rembrandt's portraits since most of his males had their right-cheek exposed and females had their left-cheek exposed. This raises questions regarding the emotional and cognitive significance of such biased positioning. Simultaneously, we measured observers pupil size while asking observers to report how (dis)pleasing they found each image. We found that in viewing male portraits pupil diameter was a function of arousal. That is, larger pupil diameter occurred for images rated both low and high in pleasantness. We discuss these findings in regard to the perceived dominance of males and how emotional expressions may be driven by hemispheric laterality.

Keywords:

• Hemispheric laterality
• Pupil size
• Face perception
• Emotion
• Aesthetic judgements

Acknowledgements

Special thanks to Rebecca White for help with data management and Lisa Scalzo for editing.

Notes

¹The estimated variance covariance matrix (G matrix) of the random effect of viewer is not positive definite, which meant that the between-subjects variation component being estimated was negative. Since it is not possible to have a negative variance, SAS automatically set the negative variance estimates to zero.