Neural Differences between Covert and Overt Attention Studied using EEG with Simultaneous Remote Eye Tracking

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Paper

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5120114/
Year: 2016

Summary

• EEG analysis of the period preceding the saccade latency showed similar occipital response amplitudes for overt and covert shifts, although response latencies differed.
• combined EEG and eye tracking can be successfully used to study natural overt shifts of attention
• There were no striking differences in early response components between overt and covert shifts in fronto-central areas
• Most studies of covert vs. overt attention involve instructing the participant to attend to a particular region of the field via a centrally presented cue, and so can be considered as an endogenous direction of attention. In contrast, our experiment provided an exogenous trigger for attention, by the appearance of a target in a peripheral field location. Thus it is possible that a different pattern of activation would be seen in the covert direction of attention by an endogenous cue

Research on neural mechanisms of attention has generally instructed subjects to direct attention covertly while maintaining a fixed gaze. This study combined simultaneous eye tracking and electroencephalogram (EEG) to measure neural attention responses during exogenous cueing in overt attention shifts (with saccadic eye movements to a target) and compared these with covert attention shifts (responding manually while maintaining central fixation). EEG analysis of the period preceding the saccade latency showed similar occipital response amplitudes for overt and covert shifts, although response latencies differed. However, a frontal positivity was greater during covert attention shifts, possibly reflecting saccade inhibition to maintain fixation. The results show that combined EEG and eye tracking can be successfully used to study natural overt shifts of attention (applicable to non-verbal infants) and that requiring inhibition of saccades can lead to additional frontal responses. Such data can be used to refine current neural models of attention that have been mainly based on covert shifts.