Cerebral asymmetry in visual attention

The traditional view of cerebral lateralization of various cognitive functions has been challenged by results from recent experimental and clinical studies. Evidence has been gathered to suggest that a seemingly unitized cognitive function can be further broken down into various processing subcomponents which are distributed across the two hemispheres. For instance, according to such a more complex conceptualization of cerebral lateralization, language is seen not as a unitary ability, but rather as a collection of syntactic, semantic, and prosodic components, with each lateralized in particular manners. In much the same way, the present study attempts to examine the cerebral lateralization patterns of the seemingly unitary visual perception process. In a visual half-field experiment, 20 normal subjects were asked to make same/different judgments to laterally presented arrays of stimuli of the same type as previously studied by Treisman and her colleagues in experiments attempting to separate the preattentive and attentive stages of visual perception. Hemispheric differences were obtained only in tasks requiring attentive processing (i.e., Treisman's glueing). Results indicate a local attentional strategy for the left hemisphere and a global attentional strategy for the right hemisphere.