The role of perceptual load in neglect: Rejection of ipsilesional distractors is facilitated with higher central load

Neglect is known to produce a bias towards the ipsilesional side. Here we e xamined whether this bias is automatic or can be modulated by manipulating perceptual load in a relevant task [e.g., Lavie, N. (1995). Perceptual load as a necessary condition for selective attention. Journal of Experimental Psychology: Human Perception and Performance, 21, 451-468]. Three patients with left neglect and three healthy controls made speeded choice responses to a target letter in the center of the display while attempting to ignore an irrelevant distractor presented on left or right. Perceptual load was ma nipulated by inducing a search for the target that appeared with another ce ntral stimulus, which was either a blob (low load) or a nontarget letter (h igher load). Response competition effects from ipsilesional distractors wer e significantly reduced by higher load. The same increase of load, however, did not decrease distractor effects in the control group, as expected [e.g ., Lavie, N., & Cox, S. (1997). On the efficiency of attentional selection: Efficient visual search results in inefficient rejection of distraction. P sychological Science, 8, 395-398]. These results demonstrate that ipsilesio nal bias in neglect is not fully automated and emphasize an additional rest riction of perceptual capacity. Moreover, they supported our prediction tha t reduced perceptual capacity in neglect can lead to improved distractor re jection with just small increases in perceptual load.