EFFECTS OF TEMPORAL AND SPATIAL SEPARATION ON VELOCITY AND STRENGTH OF ILLUSORY LINE MOTION
Effects of line length and of spatial or temporal distance between the cue and the line on perceived velocity and on perceived strength of illusory line motion (when a stationary line is perceived as unfolding or expanding away from a previously presented stationary cue) were examined in four experiments. Ratings of perceived velocity decreased with increases in stimulus onset asynchrony between appearance of the cue and appearance of the line (from 50 to 450 milliseconds), whereas ratings of perceived strength increased with increases in stimulus onset asynchrony (from 50 to 250 or 450 milliseconds). Ratings of perceived velocity increased with increases in length of the line, whereas ratings of perceived strength were not influenced by increases in length of the line. Ratings of perceived velocity and ratings of perceived strength were not influenced by increases in distance of the near end of the line or the far end of the line from the cue. Implications of the data for theories of illusory line motion that involve an attentional gradient or apparent motion are discussed.