Digit span performance and unilateral neglect.

This study tested the alternative hypotheses of Weinberg et al. (J. clin. Psychol. 28, 361, 1976) and Robertson (Neuropsychologia 28, 217-222, 1990) regarding the nature of dysfunctions underlying impaired backward digit span among patients with unilateral neglect. Results support the Weinberg et al. hypothesis that visual imagery plays a primary role in performance of Digits Backward. The findings also indicate a unilateral component to the Digits Backward task. Both neglecting and non-neglecting patients with high digit span discrepancy (DD) evidenced attentional bias to right space and a specific impairment in rotating objects in left space. Results were not consistent with Robertson's hypothesis that high DD arises from a general attentional deficit. In fact, patients with low DD evidence greatest impairment on tests of attention.