Correcting some misperceptions of time-to-collision: a critical note

Stewart et al (1993, Perception 22 1227-1224) attempted to demonstrate that the ratio of angular speed to angular acceleration, [symbol see text]/[symbol see text], of the approaching object is preferred as the source of time-to-collision information to the ratio of visual angle to angular speed, [symbol see text]/[symbol see text]. It is demonstrated that this is not justified.