Highly efficient attentional selection of colors despite high target-distractor similarity

Poster Presentation 43.340: Monday, May 22, 2023, 8:30 am – 12:30 pm, Banyan Breezeway
Session: Attention: Features

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Angus Chapman1, Viola Störmer2; 1University of California San Diego, 2Dartmouth College

A major constraining factor for attentional selection is the similarity between targets and distractors. When similarity is low, target items can be identified quickly and efficiently, while high similarity can incur large costs on processing speed. Models of visual search have explained these effects by contrasting a fast, efficient parallel stage with a slow serial processing stage where search times are strongly modulated by the number of distractors in the display. Further, recent work has argued that the magnitude of these search slopes should be inversely proportional to target-distractor similarity (Lleras et al., 2020). Here, we assessed the relationship between target-distractor similarity and search slopes. In our visual search tasks, participants detected an oddball color target among distractors (Experiments 1 & 2, N=50 each) or discriminated the direction of a triangle in the oddball color (Experiment 3, N=50). We systematically varied the similarity between target and distractor colors (along a circular CIELab color wheel) and the number of distractors in the search array. We observed logarithmic search slopes that were inversely proportional to the number of distractors in the array, consistent with recent models of efficient processing in visual search. Surprisingly, we also found that searches were highly efficient (i.e., near zero slopes) for targets and distractors that were extremely similar (~20° in color space). These findings indicate that visual search is systematically influenced by target-distractor similarity across different processing stages. Most importantly, we found that search can be highly efficient and entirely unaffected by the number of distractors despite high perceptual similarity, in contrast to the general assumption that high similarity must lead to slow and serial search behavior. Most broadly, these results point to the importance of assessing target-distractor similarity at a high resolution when the goal is to better understand attentional efficiency.