The influence of hunger on visual processing of objects

The focus of this study is to assess the influence of individuals homeostatic state (i.e. hunger) on visual processing of objects using measures of spontaneous eye blink and pupil response. Spontaneous eye blink and pupil response are closely linked with cognitive state as well as underlying neurophysiologic function, specifically autonomic function, arousal, and homeostatic state. Data was collected across two visits, one in a fasted state and another in a satiated state. Participants (current N=9; data collection ongoing) were randomly assigned to either the fasted condition or satiated condition at their first visit and completed the opposite condition at their 2nd visit. Prior to the fasting session, individuals went 8 hours with no food. For the satiated session, individuals were given food (pastries and juice) prior to participation and were instructed to “eat until you feel satiated”. At each visit, participants were presented with 256 images of faces, food, places, and visual ‘white noise’ divided across two experimental blocks. Images were presented for 2.5 seconds. Images were chosen to include categories that were relevant to the altered homeostatic drive state (food) and categories that have rewarding properties but are not relevant to the drive state (faces). Eye tracking was used to collect measures of spontaneous eye blink and pupil response while participants monitored the stimuli for the appearance of a white fixation cross. Preliminary results indicate that both pupil size and blink rate increase during the fasting state, with the greatest changes occurring in response to food images. This study suggests an influence of internal state on visual processing of object images. The impact of altered homeostatic drive appears to impact both domain-general and domain-specific responses to objects that are reflected in pupil response and blink rate.