Unseen food images capture the attention of hungry viewers: Evidence from event-related potentials

Abstract

Motivationally relevant visual targets appear to capture visuospatial attention. This capture is evident behaviorally as faster and more accurate responses, and neurally as an enhanced-amplitude of the N2pc – an index of spatial attention allocation, which is observed even when observers are unaware of the target. In the case of reinforcers such as food or substances of dependence, it is likely that the motivational state of craving accompanying deprivation potentiates this capture. The automaticity of such attentional capture by reward-associated stimuli, as well as its possible interaction with craving, is as yet not completely understood, though it is likely a major explanatory factor in motivated behaviors. For the present experiment, participants completed two EEG recording sessions: one just after eating lunch (sated/non-craving), and the other following a minimum 12-h period of fasting (hungry/craving). For both sessions, participants identified food- and clothing-related targets embedded in an object-substitution masking paradigm, which yielded trials of full target visibility, as well as trials for which targets were present but undetected. Although masking equally disrupted visual awareness of both classes of targets as measured behaviorally, a three-way hunger by visibility by target interaction was observed in the neural data, with unseen food targets eliciting an enhanced N2pc. Interestingly, this subliminal attentional capture by food-related items was observed only during the “hungry” session. No such capture was evident under conditions of full visibility. These findings indicate that attentional capture by food-related images, and reflected in enhancements of the N2pc, is spurred by hunger, and that this effect can be viewed as automatic, or independent of explicit awareness of food-relevant target content.