Spatial perception and control.

We investigated whether the perceived vanishing point of a moving stimulus becomes more accurate as one's degree of control over the stimulus increases. Either alone or as a member of a pair, participants controlled the progression of a dot stimulus back and forth across a computer monitor. They did so via right and left buttonpresses that incremented the dot's velocity rightward and leftward, respectively. The participants in the individual condition had control of both buttons. Those in the group condition had control of only one. As the participants slowed the dot to change its direction of travel, it unexpectedly disappeared. Localizations of the vanishing point became more accurate as the participants' control over the dot increased. The data bridge a gap between accounts of localization error that rely solely on stimulus and cognitive factors, and accounts derived from research on action and spatial perception, which tend to rely on action-planning factors.