Anna Grubert¹, Ziyi Wang¹, Courtney Turner¹, Kaijie Zhang¹, Daisy Searle¹; ¹Durham University

Multiple attentional templates (mental target representations) can be activated in parallel during visual search when multiple targets are task relevant. Such target representations are held in visual working memory (vWM), which storage capacity is known to differ between individuals. We tested whether individual vWM capacity predicts an individual’s ability to activate multiple attentional templates by correlating behavioural and electrophysiological measures of vWM capacity with indices of attentional selection efficiency. In a change detection task, participants memorised one, two, or three colours and then judged whether a subsequent test display was identical or contained a colour change. Individual vWM capacity was substantiated by means of Pashler’s k and amplitudes of the contralateral delay activity (CDA). In a visual search task, participants reported the orientation (vertical/horizontal) of a target-colour bar presented among five differently coloured nontargets. One, two, or three possible target colours were cued before each block. Search efficiency, indicative of the ability to activate multiple templates simultaneously, was indexed by N2pc amplitudes. In addition, we assessed the time course of template activation by measuring N2pc components elicited in response to colour singleton probes presented prior to the search displays. Both tasks produced load effects: Increasing memory load yielded higher k values and larger CDA amplitudes in the change detection task, while increasing the number of target colours reduced N2pc amplitudes during search. Critically, substantial individual capacity differences emerged in the change detection task, and these differences predicted visual search performance reliably. Individuals with higher k values and larger CDA amplitudes showed smaller N2pc load costs, demonstrating their ability to search with multiple concurrent templates. These individuals also demonstrated earlier and simultaneous template activation in preparation for search. Together, our results suggest that individual vWM limits predict an individual’s ability to activate multiple templates simultaneously in multiple-colour search.

Acknowledgements: This work was funded by a research grant of the Leverhulme Trust (RPG-2020-319).