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

Attention to visual features can guide visual search. While research has shown that color is a more powerful guiding attribute than orientation, this may partly be explained by stimuli parameters and distractor heterogeneity favoring color selection. Here, we tested this with closely-matched visual search tasks that isolated feature-based top-down guidance. Participants searched for a target T among distractor Ls (1T and 7Ls or all 8Ls). In the color task, the target could be either red or blue while distractors were in six other colors and red and blue. In the orientation task, the target could be either vertical (0° rotated upright letter) or horizontal (270° rotation) while distractors were in six oblique orientations or 0° and 270°. If a target was present, distractors did not share its feature. In both tasks, participants experienced cued and uncued blocks. In the cued blocks, the color (red/blue) or orientation (vertical/horizontal) of the target was cued with 100% validity and participants were instructed to use them to search for T. No cues were provided in the uncued block. We found that while color cueing significantly speeded responses, orientation cueing actually slowed responses. We reasoned that the letter stimuli might have rendered the orientation cueing detrimental as the stimuli consisted of orthogonal lines. Thus, we conducted a follow-up experiment with the same paradigm but using elongated shapes (rectangles with rounded or pointed ends) instead of letters. We found that color cueing speeded responses while orientation cueing had no effect on response times. Overall, our findings support previous reports and indicate that color more effectively guides visual search than orientation, in a well-matched design with heterogeneous distractors. The dominance of color may be due to its greater invariance and saliency. Future studies may explore the stimulus parameters that can enable effective orientation cueing.

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