Limb activation and the rehabilitation of unilateral neglect: Evidence of task-specific effects

The present study investigated the effectiveness of limb activation as a rehabilitation technique for visual neglect. Patients made left limb movements in left space or right limb movements in left space and performance was compared to that under no-limb-movement control conditions. The effects observed on a simple digit report task were equivocal and limb activation did not produce consistent improvements in the patients' ability to report left-sided stimuli. In a second study, the patients' eye movements were recorded while they performed a simple overt orienting task under limb activation conditions. There was no improvement in the leftward saccades made by any patient under either limb activation condition. A third study examined the effects of limb activation on the frequency of whole-word omissions in text reading. The number of left-sided whole-word omissions was reliably reduced with concurrent left limb activation. Furthermore, a smaller reduction in whole-word omissions was observed following right limb activation. It was also found that left-sided word omissions were reduced when limb activation was performed prior to the reading task, rather than concurrently. It is suggested that limb activation may improve overt orienting in tasks requiring voluntary control, but not when the task has an automatic reflexive component.