The consequences of color chromaticity on electrophysiological measures of attentional deployment in visual search.

We investigated to what extent color vividness of visual items influences how humans prioritize information in a search task. For this, color chromaticity was manipulated over two search experiments. While recording the electroencephalogram, participants searched for a shape of certain color among three other shapes, when it emerged from a stream of flickering gray placeholders. Each location was tagged with a specific frequency evoking the steady-state-visual-evoked potential (SSVEP) allowing to track attentional deployment on multiple items. Color vividness boosted SSVEP amplitudes independent of item type, i.e., targets or distractors, while leaving other measures of attentional deployment-event-related potentials and alpha-band amplitudes-mostly unaffected. Interestingly, relative modulation of target and distractor SSVEP amplitudes was comparable between experiments suggesting similar attentional deployment. The results highlight that attentional deployment to search items depends on low-level stimulus features that need to be controlled to allow for inferences about capture or suppression of individual items.