Attentional Engagement and Disengagement: Quantifying Attentional Shifts Utilizing the Steady State Visual Evoked Potentials

In the present study we aimed to measure and discern between attentional shift processes. We utilized the EEG frequency tagging technique in an experimental design that required participants to switch their attentional focus between four stimuli flickering at distinct frequencies. Through the analysis of steady-state visual-evoked potential (ssVEP) responses we were able to study the time course and temporal dynamics of different attentional shifts. Specifically, engagement with a to-be attended target, disengagement from a previously attended target and reengagement with a new target. Importantly, our experimental design and analysis allowed for measuring these processes not only on the group, but also on the individual subject level. On the group-level, both attentional disengagement and reengagement were evident, with the process of disengagement occurring prior to reengagement. Interestingly, on the individual subject level several distinct patterns of attentional shifts emerged: While a major portion of participants mirrored the group-level trend, in a subgroup of participants only attentional disengagement could be identified, in some only reengagement, and others showed no discernible shifts in ssVEP amplitude. Notably, the timing of these attentional shifts varied across individuals relative to target switch events. Echoing prior studies, our findings shed light on the independent and gradual nature of attentional shift processes and underscore the importance of examining these shifts at both the group and individual levels. Our study provides deeper insights into the neural mechanisms that drive attentional dynamics.