Abstract
Patients with visuospatial neglect and/or extinction respond much more slowly to a stimulus presented to their impaired, contralesional side of space when it is preceded by a stimulus presented to the intact, ipsilesional side of space. This response pattern is referred to as a disengage deficit, indicating that attention is slow to be disengaged from ipsilesional stimuli. Past studies have measured the disengage deficit for reflexive orienting (nonpredictive peripheral onsets) and volitional orienting (predictive central arrows). Recent evidence that nonpredictive arrows engage reflexive attention, however, implies that past studies using predictive arrows confounded reflexive and volitional attention. We therefore examined the disengage deficit in the same participants for when an attention cue engages only reflexive attention (nonpredictive peripheral onsets and arrow cues), reflexive and volitional attention (predictive peripheral onsets and arrow cues), and only volitional attention (predictive number cues). Results indicate that the significant disengage deficit for reflexive orienting (nonpredictive onsets and arrows) was unmoved when volitional attention was also engaged (predictive onsets and arrows), suggesting that volitional orienting does not contribute to disengage difficulties. This interpretation was confirmed when only volitional attention was manipulated by predictive number cues: significant cuing effects for contra- and ipsilesional fields were observed but there was no disengage deficit. The results are discussed with respect to their implications for understanding the attentional mechanisms underlying the disengage deficit as well as its assessment and rehabilitation in patient populations.
This work was supported by grants from the Michael Smith Foundation for Health Research and the German Academic Exchange Service (DAAD) awarded to B. Olk and by Canadian grants from the Natural Sciences and Engineering Research Council, and the Social Science and Humanities Research Council awarded to A. Kingstone.