Arrangement of Numbers in Clock Drawings by Patients of Unilateral Spatial Neglect

Abstract

  In this study, factors associated with the arrangement of numbers on a clock drawing were investigated in cases of unilateral spatial neglect (USN) . The subjects were 32 patients with USN who could not draw a clock correctly. The transposition index (TI) , which refers to distribution rate of outer numbers in the outer number on the left and right sides, was used to analyze number placement. We analyzed the following four items: 1) the association between TI and the site of damage, 2) association between TI and laterality index (LI) in a line cancellation task, 3) reaction when numbers were placed in the counter-clockwise direction, and 4) reaction when a single number was placed. The results indicated that deviations in number placement differed according to cases and TI was widely distributed. Furthermore, in cases in which numbers were only distributed only on the right side in the outer circle, two different reactions were confirmed; some subjects placed ≤6 numbers and other subjects filled in ≥6 numbers, representing cases of parietal lobe impairment and extensive brain damage including the frontal lobe, respectively. No correlation was observed between TI and LI. When placing numbers counter-clockwise or a single number, some cases did not show any deviation in number placement. These results suggested that errors in figure placement in a clock drawing by USN cases are affected by other impairments accompanying USN.