title: Global statistical regularities modulate the speed of visual search in patients with focal attentional deficits.
abstract: There is growing evidence that the statistical properties of ensembles of similar objects are processed in a qualitatively different manner than the characteristics of individual items. It has recently been proposed that these types of perceptual statistical representations are part of a strategy to complement focused attention in order to circumvent the visual system's limited capacity to represent more than a few individual objects in detail. Previous studies have demonstrated that patients with attentional deficits are nonetheless sensitive to these sorts of statistical representations. Here, we examined how such global representations may function to aid patients in overcoming focal attentional limitations by manipulating the statistical regularity of a visual scene while patients performed a search task. Three patients previously diagnosed with visual neglect searched for a target Gabor tilted to the left or right of vertical in displays of horizontal distractor Gabors. Although the local sizes of the distractors changed on every trial, the mean size remained stable for several trials. Patients made faster correct responses to targets in neglected regions of the visual field when global statistics remained constant over several trials, similar to age-matched controls. Given neglect patients' attentional deficits, these results suggest that stable perceptual representations of global statistics can establish a context to speed search without the need to represent individual elements in detail.
authors: Center for Mind/Brain Sciences, University of Trento Rovereto, Italy ; Center for Neurocognitive Rehabilitation, University of Trento Rovereto, Italy ; Cognitive Neuropsychology Lab, Harvard University Cambridge, MA, USA.
authors: Lucilla
authors: L
authors: Lanzoni
authors: Center for Mind/Brain Sciences, University of Trento Rovereto, Italy.
authors: David
authors: D
authors: Melcher
authors: Center for Mind/Brain Sciences, University of Trento Rovereto, Italy ; Center for Neurocognitive Rehabilitation, University of Trento Rovereto, Italy.
authors: Gabriele
authors: G
authors: Miceli
authors: Center for Mind/Brain Sciences, University of Trento Rovereto, Italy.
authors: Jennifer E
authors: JE
authors: Corbett
keywords: attention; ensemble statistics; mean size representation; perceptual averaging; visual neglect; visual search