Selection and binding of visual features outside of the focus of attention

Abstract

Purpose. It is widely believed — although not tested directly — that global attentional modulation, which is present outside the focus of attention will affect selectively the processing of the visual feature that is attended inside the focus. Our goal was to determine the units of selection outside the focus of attention. Methods. We tested whether global attentional modulation outside the focus of attention will spread to task-irrelevant features of those unattended objects that share the attended feature (cross-feature attention: CFA). In the first experiment we investigated whether the duration of the motion aftereffect (MAE) evoked by the unattended motion signal present in one of the visual hemifields is modulated, depending on whether the attended color in the opposite hemifield did or did not match the color of the MAE-producing moving dots during adaptation. In the second experiment, we measured CFA effects on a subthreshold motion prime and thus excluded the possibility that the motion signal was attended directly. Results. The processing of both the adapting motion signal and the sub-threshold motion prime outside the focus of attention was strongly modulated depending on whether the color they were associated with matched or did not match the color that was attended inside the focus of attention. With control experiments we ruled out the possibility that the color-to-motion CFA effects found in the present study were due to some spared attentional resources allocated to the unattended hemifield with the motion prime. Conclusion. Visual features that originate from the same spatiotemporal location are bound throughout the visual field and as a result the units of global selection outside of the focus of attention are bound clusters of spatiotemporally co-occurring visual features.

Footnotes

 Supported by grants from the Hungarian National Research and Development Program (2/035) and NEI/NIH EY 013758-01