The Aesthetic and Economic Value of Social and Non-Social Stimuli Seen from an Eye-Tracker : Pupillary Changes and Eye Fixations can Index the Aesthetic Value of HumanFaces as well as of Wine Labels

Abstract The present study examines the effect that hedonic value can have on economic decisions (e.g., willingness to pay) as well as oculomotor behavior and pupillary responses (i.e., measures of the allocation of attention). Due to the well-known interactions between reward circuitry in the brain, modes of activity in the LC, and pupillary dilations (Aston-Jones & Cohen, 2005; Laeng, et al., 2012), pupillometry with eye tracking should be a promising method to study the effect of hedonic stimuli. To our knowledge, no previous study has provided evidence that changes in the eye pupil’s diameter can index parametrically the hedonic response (i.e., proportionally to the level of attractiveness of either social or non-social stimuli). Specifically, pupillary changes along with eye fixations of 49 participants were monitored while they were viewing images of either human faces or wine bottles. Both sets of stimuli had initially being rated by an independent group of 80 participants for their hedonic value. Participants made economic decisions by estimating either price or salary that participants would be willing to give for each wine bottle or person, respectively. Results showed a linear increase in pupil dilations in response to parametric increases in facial attractiveness, whereas non-linear, i.e. U-shaped, pupillary changes were registered in response to wine labels. Moreover, above median level of attractiveness in faces and wine labels triggered, respectively, smaller and greater numbers of eye fixations. The data from economic decisions revealed a linear increase in the level of offered monetary payoffs as a function of hedonic level for both faces and wine labels. Areas of interest analyses revealed the visual features that attracted the most attention and a left-side laterality effect. Finally, only facial attractiveness showed gender-dependent effects on both economic decisions and biological responses.