Nora Indenberga¹ (), Seeun Oh¹, Sydney T. George¹, Melisa Menceloglu¹, Taosheng Liu¹; ¹Department of Psychology, Michigan State University

Feature-based attention operates globally, modulating neural responses to stimuli inside and outside of the focus of spatial attention, which is assumed to enable guided visual search. Because feature dimensions differ in their guiding power (e.g., color > orientation), this may be also reflected in their ability to spread. Here, we compared the global spread of attention to color and orientation. We used a dual-task paradigm where participants maintained central fixation and completed a primary task on one side and a secondary task on the other side of fixation. In the color version, participants were cued to attend to one of two overlapping red and blue dot fields to detect occasional dimming in the primary task, while discriminating which of two separate groups of dots in 8 colors contained an overrepresentation of red or blue in the secondary task, regardless of the cue. In the orientation version, participants were cued to attend to vertical or horizontal lines to detect occasional dimming in the primary task while discriminating which of the fields of lines with 8 orientations contained an overrepresentation of vertical or horizontal lines in the secondary task. For both, the feature cue was only predictive for the primary task. We compared accuracy on the secondary task as a function of match vs. mismatch between the cued and overrepresented feature to quantify the global spread. We observed a spread effect for color and only marginal effect for orientation with no difference between those effects. In a follow-up experiment, we strengthened the attentional selection of the feature for the primary task and observed greater and significant spread effects both for color and orientation, which were comparable. Our results may suggest that the differences in guiding power between features may be due to reasons other than their ability to be selected globally.

Acknowledgements: Funding Information: NIH (R01EY032071) and NSF (2019995)