Attentional control parameters following parietal-lobe damage: evidence from normal subjects.

Attentional control involves the factors, or cognitive parameters, that determine which environmental inputs receive attention and which do not. Cognitive studies of attentional control have highlighted two general classes of control parameters, bottom-up (data driven or exogenous) parameters and top-down (goal driven or endogenous) parameters. Which of these control parameters is affected following parietal-lobe damage? In parietal-damaged patients, it is possible that a disorder in one control parameter (e.g. goal driven) would appear as a disorder in another parameter (e.g. data driven). To investigate the control parameters that might be affected in parietal patients, we simulated neglect in normal participants by disrupting data-driven information processing. When half of a computer monitor was degraded by translucent tracing paper while normal participants performed a cued spatial attention task (Experiment 1), the normal participants showed a pattern of results similar to patients with unilateral parietal-lobe damage--the so-called "disengage deficit." This pattern of results replicated when neutral attentional cues were included in the experiment (Experiment 2). However, the disengage deficit was not simulated in normal participants with predictive central symbolic cues (Experiment 3) or predictive peripheral cues (Experiment 4). Because perceptual degradation influences data-driven attentional control parameters, we suggest that these control parameters may be disrupted following parietal-lobe damage.