Diagnostic parts are not exclusive in the search template for real-world object categories

Visual search can be aided by a search template: a preparatory representation of relevant target features. But which features are relevant in complex, real-world category search? Previous research suggests that this template must be flexible to account for variations in naturalistic stimulus properties such as size and occlusion, and that shapes of diagnostic parts of objects are a likely candidate. Here, in three experiments, we systematically evaluated the contribution of diagnostic object parts and whole object shape to the category-level search template. Our hypothesis was that features that better match the active search template will capture attention during search more strongly than partially-matching features. Results showed that while whole objects captured attention reliably and globally across the visual field, diagnostic parts failed to do so in all three experiments. This suggests that whole object shape is a necessary component of the category-level search template.