SPLTRAK Abstract Submission
Misrepresentation of motion direction causes prediction errors in multiple object tracking
Rebecca St. Clair, Adriane E. Seiffert
Department of Psychology, Vanderbilt University

Do people use local motion information to predict the future locations of targets during multiple object tracking?  Our previous research suggested this may be true because tracking accuracy was lower when the motion of texture on the targets conflicted with the motion of the targets themselves compared to when it did not (St. Clair, Huff, & Seiffert, 2010, JOV).  However, these findings allowed for the possibility that it was the perception of object position and not object motion that was affected by the texture motion.  Here, we investigated whether the motion direction is misrepresented for objects with conflicting texture motion.  Observers tracked 3 of 10 dots that moved independently and linearly in a box filled with random-dot texture.  The dots were either grey or filled with a random-dot texture that moved at 2 times the dot speed in either in the same direction, the opposite direction, or orthogonal to each dot's trajectory.  At the end of the tracking period, observers used the mouse to adjust the orientation of a line to match the direction of motion of a randomly-chosen target.  The mean absolute error was lower for grey targets (38°) and targets with same-moving textures (35°) than for opposite-moving textures (56°; t(12) = 4.58, p <0.01) and orthogonal-moving textures (59°; t(12) = 4.60, p <0.01).  These findings are consistent with our hypothesis that people misrepresent the direction of objects with conflicting texture motion.  The misrepresentation of direction causes inappropriate predictions of future target locations that result in tracking errors.