title: Visual search asymmetry with uncertain targets.
abstract: The underlying mechanism of search asymmetry is still unknown. Many computational models postulate top-down selection of target-defining features as a crucial factor. This feature selection account implies, and other theories implicitly assume, that predefined target identity is necessary for search asymmetry. The authors tested the validity of the feature selection account using a singleton search task without a predefined target. Participants conducted a target-defined and a singleton search task with a circle (O) and a circle with a vertical bar (Q). Search asymmetry was observed in both tasks with almost identical magnitude. The results were not due to trial-by-trial feature selection, because search asymmetry persisted even when the target was completely unpredictable. Asymmetry in the singleton search was also observed with more complex stimuli, Kanji characters. These results suggest that feature selection is not necessary for search asymmetry, and they impose important constraints on current visual search theories.
authors.affiliation: Graduate School of Informatics.
authors.forename: Jun
authors.initials: J
authors.lastname: Saiki
authors.affiliation: Graduate School of Informatics.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Koike
authors.affiliation: Graduate School of Informatics.
authors.forename: Kohske
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Graduate School of Informatics.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Inoue
mesh_terms: D002755:Choice Behavior; D006801:Humans; D008962:Models, Theoretical; D014796:Visual Perception