VISUAL AND MOTOR COMPONENTS IN SIMPLE LINE BISECTION - AN INVESTIGATION IN NORMAL ADULTS

Visuomotor bisection and bisection judgement of centrally presented 10 -cm horizontal lines were proposed to 43 normal adults, both on paper and on the vertical screen of a computer. Tasks on paper showed slight left-side of the line overestimation and weak link between actual bis ection and judgement. Tasks on screen showed, on the contrary, right-s ide of the line overestimation and stronger link between actual bisect ion and judgement. Centrally pretransected lines were often judged wro ngly. These results suggest an important role of motor factors on clas sical paper-and-pencil visuomotor line bisection, and the relevance of the distinction between peripersonal and extrapersonal space.