Initial rightward orienting bias in clinical tasks: normal subjects and right hemispheric stroke patients with and without neglect.

In order to develop the diagnosis of hemi-inattention in patients with right hemispheric cerebrovascular accident (RCVA), the initial starting point of cancellation performance was studied in seven commonly used visual cancellation tasks, an Object Finding task, and a blindfold Tactuo-motor search task. The subject groups consisted of 34 patients with RCVA and 31 healthy subjects. Patients were divided into groups of contralateral neglect and no neglect. One additional case of ipsilesional neglect and one of nonlateralised attentional disorder in relation to early orienting bias, are reported. Patients with contralateral neglect showed a strong tendency to start their cancellation performance on the right. Also, half of the nonneglect patient group demonstrated right bias in initiating their cancellation performance, suggesting the presence of a subclinical hemi-inattention group. Contrary to expectations, also a small proportion of normal subjects were right-biased. Task dependent differences in the assessment of early rightward orienting bias were found.