Exploring emotional biases in vision using electrophysiology during free viewing conditions

Elucidating the neural mechanisms that subserve conscious awareness is a fundamental goal of neuroscience. There is abundant evidence that conscious perception is gated by the ability to direct attention to behaviorally relevant stimuli in the environment, through top-down modulation of sensory pathways by attention control networks. Attention can be directed by internal goals (endogenous) or salient external cues (exogenous). There is also evidence that attention can be guided by emotional significance of stimuli even when these are goal-irrelevant (1), suggesting that emotional information can be detected prior to conscious awareness (2). The exact neural pathways and timing of these emotional effects remain unresolved, as well as their relationship to other attention mechanisms (3). Non-invasive electrophysiological methods with EEG and MEG provide powerful tools to dissect the specific types and stages of processing that controls how attention is directed to sensory stimuli (2) and can now be applied to ecological free-viewing conditions (4-7) rather than unnatural experimental paradigms as used in many studies (3). Here we will exploit the latter approach by combining expertise from both labs on emotion perception (1, 2, 3) and combined EEG-eyetracking methodology (4,5). We will record fixation-related brain potentials (FRPs) while participants freely explore visual scenes and direct their gaze at stimuli with different properties: either goal-relevant (target objects to be searched/counted), emotionally significant but task-irrelevant (e.g. faces, animals), or physically salient and irrelevant (based on sensory feature analysis of pictures (8). FRPs will allow us to identify and compare neural signatures for different conditions of attentional capture.