Abstract
When attending to a feature in the visual environment (e.g., the color red), sensory processing of stimuli sharing that feature is enhanced throughout the visual field. These global effects of feature-based attention are observed in lower visual areas for simple features such as color or orientation (Saenz et al., 2002) and have been shown to extend to basic shape processing in higher visual area LO (Peelen & Kastner, 2009). Here, by examining the face-specific N170 component in the EEG signal, we asked if the global spread of attention would be observed for higher levels of face processing. We presented grayscale images from different categories (faces, buildings, cars, chairs, fish) in a rapid RSVP stream presented either in the left or right visual field, and asked participants to covertly attend to either faces or buildings while recording their brain’s electrical activity. During each trial, task-irrelevant images of faces or houses were briefly presented at random intervals in the unattended visual field (“probes”). On half of the trials, no target image was present in the RSVP stream, and these trials were used for the EEG analysis. We measured the event-related potentials (ERPs) elicited by the task-irrelevant probes and identified the face-sensitive N170 component at posterior electrode sites by comparing ERPs elicited by faces relative to houses. Next, we compared the N170 when participants attended to faces vs. buildings in the RSVP stream. We found an increased N170 (p=0.02) when participants performed the face task, suggesting that neural processing of faces – as indexed by the N170 component – was enhanced throughout the visual field. There was no attentional modulation of the ERPs elicited by house stimuli (p=0.50). These results suggest that when attention is tuned to complex, real-world face stimuli, tuning extends across the visual field, even to unattended locations.
Meeting abstract presented at VSS 2015