The optimal motion stimulus: comments on Watson and Turano (1995)

Watson and Turano (Vision Research 1995;35:325-336) described experimental research aimed at determining the motion stimulus that the visual system detects best. They reported conflicting results in the determination of the optimal spatial size and they interpreted them as an effect of probability summation. They also reported disagreement with earlier results of Watson et al. (Nature 1983;302:419-422). This study shows (i) that probability summation is not responsible for those results and (ii) that they can be explained as a consequence of the method that was used to search for the optimal stimulus.