title: Foveal target repetitions reduce crowding.
abstract: Crowding is the limitation of peripheral vision by clutter. Objects that are easily identified when presented in isolation are hard to identify when presented flanked by similar close-by objects. It is often assumed that the signal of a crowded target is irretrievably lost because it is combined with the signals of the flankers. Here, we asked whether a target signal can be enhanced (or retrieved) by items presented far outside the crowding region. We investigated whether remote items matching a peripheral, crowded target enhanced discrimination compared to remote items not matching the target. In Experiment 1, we presented the remote item at different locations in the visual field and found that, when presented in the fovea, a matching remote item improved target discrimination compared to a nonmatching remote item. In Experiment 2, we varied stimulus onset asynchronies between target and remote items and found a strong effect when the remote item was presented simultaneously with the target. The effect diminished (or was absent) with increasing temporal separation. In Experiment 3, we asked whether semantic knowledge of a target was sufficient to improve target discrimination and found that this was not the case. We conclude that crowded target signals are not irretrievably lost. Rather, their accurate recognition is facilitated in the presence of remote items that match the target. We suggest that long-range grouping mechanisms underlie this "uncrowding" effect.
authors.affiliation: Laboratory of Experimental Psychology, University of Leuven, Leuven, Belgium Université Paris Descartes, Sorbonne Paris Cité, Paris, France CNRS UMR 8158, Paris, France.
authors.forename: Bilge
authors.initials: B
authors.lastname: Sayim
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Paris, France CNRS UMR 8158, Paris, France Experimental Psychology, University College London, London, UK.
authors.forename: John A
authors.initials: JA
authors.lastname: Greenwood
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Paris, France CNRS UMR 8158, Paris, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Cavanagh
mesh_terms: D015350:Contrast Sensitivity / Q000502:physiology*; D003441:Crowding; D003463:Cues; D005584:Fovea Centralis / Q000502:physiology*; D006801:Humans; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011601:Psychophysics; D014794:Visual Fields / Q000502:physiology
keywords: crowding; cueing; grouping; long-range interaction; masking; peripheral vision; similarity; uncrowding; unmasking