The severity of visual hemineglect follows a bimodal frequency distribution

The purpose of this study was to determine whether the severity of visual hemineglect follows a unimodal or bimodal frequency distribution. Seventy-seven consecutive patients with a unilateral cerebral infarct (36 left- and 41 right-hemisphere lesions) were evaluated. The severity of neglect was measured as the number of omissions on a line cancellation task. The frequency distribution of the number of lines omitted was bimodal following right lesions. One group of patients showed no or only mild neglect, whereas other patients showed severe neglect. Very few patients showed neglect of intermediate severity. The frequency distribution following left lesions was unimodal. Most patients exhibited no or only mild neglect. These results suggest that, following right lesions, the dichotomy regarding the severity of neglect is real and cannot be explained by observers' tendency to categorize.