Around the clock surveillance: simple graphic disturbance in patients with hemispatial neglect carries implications for the clock drawing task.

BACKGROUND Drawing, and the clock drawing task in particular, is widely used as a diagnostic tool in the study of hemispatial neglect. It is generally assumed that the errors in graphic production, such as the misplacement of numbers, reflect a visuospatial deficit, and that drawing production itself (for example, producing the circle) is unimpaired. OBJECTIVES To test this assumption by examining whether the production of simple circles is affected by neglect. METHODS 16 right hemisphere stroke patients copied circles of various sizes and their drawings were measured for size accuracy. RESULTS Patients with more severe neglect produced greater scaling errors, consistently drawing the circle smaller than the original. Errors were not in the horizontal axis alone--shrinkage occurred equally in both height and width axes. CONCLUSIONS Neglect can co-occur with constructional difficulties that serve to exacerbate the symptoms presented. This should be taken into account in the assessment of even apparently simple drawing tasks.