Individual differences in PROP bitterness responsiveness modulate visual awareness of food stimuli

Individuals with heightened taste sensitivity often exhibit broader sensory responsiveness to food stimuli, yet little is known about whether individual differences in gustatory sensitivity influence visual food processing. In this exploratory study, we examined whether sensitivity to 6-n-propylthiouracil (PROP) bitterness also influences the visual processing of food stimuli, specifically processed and highly processed sweet and salty items with comparable caloric content. Using the breaking Continuous Flash Suppression (bCFS) and Binocular Rivalry (BR) paradigms, we measured the speed of unconscious processing and perceptual dominance, respectively, in relation to visual awareness. Participants were assessed for their familiarity and liking of food, and the Multidimensional Assessment of Interoceptive Awareness-2 and the Eating Disorder Inventory-2 questionnaires were administered. Our findings indicate that sweet stimuli reached awareness (bCFS) significantly faster than salty stimuli, and that individuals with higher PROP responsiveness showed faster access to both categories. Perceptual dominance (BR) for sweet stimuli was also positively correlated with PROP responsiveness, further supporting the contribution of individual differences in taste perception to the modulation of visual perception. Neither familiarity nor liking of the food stimuli influenced bCFS detection latencies or BR dominance durations. To our knowledge, this is the first study to show that heightened individual gustatory responsiveness modulates visual awareness of food. These findings offer new insights into the interplay between taste and vision.