Influence of contextual stimuli on line bisection.

The influence of contextual stimuli on line-bisection performance was investigated. Subjects were required to bisect lines flanked at one end by one pair of solid black rectangles. Bisection was performed along three orthogonal axes (horizontal, radial, vertical). The results showed the presence of a bisection bias in the direction opposite to the location of flanking rectangles. This finding suggests that the presence of rectangles beside one end of a line interfered with representation of the line as a whole and induced the subjects to neglect the flanked part of the line.