Perceptual grouping operates independently of attentional selection: Evidence from hemispatial neglect

Sarah Shomstein, Ruth Kimchi, Maxim Hammer, Marlene Behrmann

Research output: Contribution to journalArticlepeer-review


To what extent can human observers process visual information that is not currently the focus of attention? We evaluated the extent to which unattended visual information (i.e., that which appears on the neglected side of space in individuals with hemispatial neglect) is perceptually organized and influences the perceptual processing of information on the attended side. To examine this, patients (and matched controls) judged whether successive, complex checkerboard stimuli (targets), presented entirely to their intact side of space, were the same or different. Concurrent with this demanding task, irrelevant distractor elements appeared on the unattended side and either changed or retained their perceptual grouping on successive displays, independently of changes in the ipsilesional task-relevant target. Changes in the grouping of the unattended task-irrelevant distractor elements produced congruency effects on the attended target-change judgment to the same extent in the neglect patients as in the control participants, and this was true even in those patients with severe attentional deficits. These results suggest that some perceptual processes, such as grouping, can operate in the absence of attention.

Original languageEnglish
Pages (from-to)607-618
Number of pages12
JournalAttention, Perception, and Psychophysics
Issue number3
StatePublished - Apr 2010

Bibliographical note

Funding Information:
This work was supported by National Institute of Neurological Disorders and Stroke Grant No. NS07391-09 to S.S. and National Institute of Mental Health Grant No. MH54246 to M.B.

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Sensory Systems
  • Language and Linguistics
  • Linguistics and Language


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