Authors:

PEERS, P., LUDWIG, C., RORDEN, C., CUSACK, C., Driver, J., Bundesen, C., Duncan, J

Reference:

Year of publication:

2002

CBU number:

5434

Abstract:

Bundesen's Theory of Visual Attention (TVA) provides a quantitive framework for measurement of several distinct aspects of visual and attentional function. Principal components of the theory include processing capacity (C), reflected in overall speed of uptake of visual information, the ability to alter attentional weights to allocate more resources to behaviorally relevant stimuli (alpha), and the capacity (k) of short term visual storage. In the present study, patients with unilateral parietal and frontal lobe injuries, along with age matched controls, were tested on a series of tasks designed to measure each of these TVA parameters. Tasks included single stimulus report at different exposure durations, partial and whole report tasks, and clinical measures of verbal and visual working memory. It was found that unilateral brain injury was associated with gloval reductions in processing capacity C (slowing in the uptake of visual information), as well as reduced attentional weights for the contralesional side of space. Storage capacity (K) was closely correlated with performance on measures of working memory in both controls and patients, although there was evidence that impairment on K following unilateral brain damage could not be explained purely by a more general working memory deficit. The data suggest that the deficits observed in patients are the result of a combination of impairments and cannot be explained fully by a simple reduction in the reduction in the allocation of attentional resources to the contralesional side.