Abstract
Access to visual awareness is modulated by markers of social relevance, including facial expression, gaze direction, and social face traits such as dominance. The neuronal mechanisms mediating this modulation remain incompletely understood. During binocular rivalry, observers’ perceptual experience alternates between two different monocular images. This allowed us to measure how markers of social relevance affected visual competition during rivalry. We hypothesised that dominant faces would be associated with slowed switch rates, and this modulatory effect would correlate with BOLD signal changes in inferior frontal gyrus (IFG). Stimuli comprised monocularly presented faces (measuring 0 or +3SD along a trait dominance dimension; Oosterhof & Todorov, 2008), and Gabor patches presented to the other eye. In a behavioural experiment, 69 participants reported their perception by holding one of three buttons to indicate perception of a face, grating, or mixture. In a second imaging experiment, 19 of these individuals performed the same behavioural paradigm while undergoing BOLD contrast fMRI using a 3T Siemens Trio. Each rivalry period was matched with a ‘replay’ period: non-rivalrous stimuli reproduced the sequence of percepts through binocular stimulation and transitions yoked to the preceding rivalry period. In the behavioural experiment, binocular rivalry switch rate was significantly slower in socially dominant compared to neutral-face trials. In the neuroimaging experiment, perceptual transitions during binocular rivalry engaged a fronto-parietal network, including right insula and superior parietal lobule. Perception of dominant faces was associated with activity in fusiform face area bilaterally, left superior temporal sulcus (STS) and left IFG. The interaction between main effects of rivalry and face dominance, highlighting regions differentially responsive during rivalry/replay depending on social dominance, was reflected in activation bilaterally in IFG, STS, and amygdala, and hypothalamus. These results demonstrate that socially relevant facial cues modulate access to visual awareness and provide new insight into the underlying neural mechanisms.
Meeting abstract presented at VSS 2013