Emotional perception: The role of visual attention, awareness, and perceptual decisions

The processing of emotion-laden information is often described as "automatic", namely, independent of attention and even visual awareness. In a series of studies we have sought to carefully test this idea with both behavioral and fMRI methods. Our findings do not favor the "automaticity" assumption and, instead, reveal that both attention and task relevance (whether a stimulus was a target or a distractor) strongly modulate responses evoked by emotional faces. In more recent studies we have investigated the neural correlates of near-threshold emotional perception. Unlike previous studies, we did not find evidence for differential responses to masked fearful faces when awareness was characterized via signal detection theory at the single-participant level. In addition, responses were reliably driven by the subject's percept, and less so by the physical stimulus per se - this was the case even in the amygdala. Finally, I will present recent results on the neural correlates of perceptual decision making while subjects performed difficult detection and discrimination tasks. Our analysis of fMRI data with both univariate and multivariate statistical and machine learning techniques revealed that (1) behavioral decisions could be predicted with high accuracy (at times approaching 90%) and that (2) the neural correlates of perceptual decisions may be encoded in a distributed fashion in the brain. Collectively, these studies show that while emotional stimuli may comprise a privileged stimulus category, their processing is highly dynamic and depends on the interplay of a host of factors that sculpt the associated neural responses, including task context, attention, awareness, and perceptual interpretation.