Spatial attention shifting to emotional faces is contingent on awareness and task relevancy

Abstract

The relationship between visual attention and visual awareness has long been hotly debated. There has been limited evidence on whether the neural marker of spatial attention precedes or succeeds that of visual awareness in the processing of emotional faces. The current study aims to investigate the temporal sequence between the electrophysiological signatures of visual awareness (the visual awareness negativity - VAN) and spatial attention (the N2pc), in contexts where emotional faces are task-relevant (Experiment 1) or task-irrelevant (Experiment 2). Fifty-six healthy participants were presented with fearful and neutral faces under different levels of visibility using backward masking. They either performed a face detection task (Experiment 1) or a contrast detection task while ignoring the faces (Experiment 2). Compared to subliminal stimuli, supraliminal stimuli produced more negative ERPs at 170-270 msec and 210-310 msec in Experiments 1 and 2, respectively, identified as the VAN. The P3, a component also frequently considered to reflect awareness, produced a similar effect with larger amplitudes for supraliminal than subliminal stimuli in both experiments. With respect to spatial attention, a significant N2pc was observed in response to fearful faces but only in the supraliminal viewing condition of Experiment 1, in which faces were task-relevant. Crucially, the VAN was found to precede the N2pc in this case. Our results suggest that spatial attention as indexed by the N2pc, is oriented towards fearful faces when they are relevant to participants' task and are consciously processed. Moreover, an early phenomenal stage of awareness, reflected by the VAN, precedes spatial attention shifting to fearful faces.

Keywords: Emotional faces; N2pc; Spatial attention; VAN; Visual awareness.