Age-related differences in distractor interference on line bisection.

Using a bisection paradigm, we investigated age-related differences in susceptibility to distractor interference. Older and younger participants were asked to bisect a horizontal line flanked by a pair of distractors, placed in either left or right hemispace. The results showed that (1) in both groups the distractors interfered with line bisection so that the localization of subjective midpoint was selectively shifted away from their position; (2) the shifting of subjective midpoint was greater in the older than in the younger group when the distractors were placed in the left hemispace. We suggest that the increase of the bisection bias in the older group depends on changes in attentional mechanisms involved in inhibiting irrelevant information.