Fig. 4.

Direction discrimination performance (solid lines) is plotted on the primary y-axis as a function of ISI duration for high and low luminance (left column and right column respectively). Performance of 100% occurs when observers perceived continuous apparent motion of the two-stoke stimulus (clockwise motion for the example given in Fig. 1). The first five rows are results for the individual observers and the final row is the mean average of the observers with error bars of ±1 SE of the group mean. The secondary y-axis plots the model output (dashed lines) against ISI duration for the best fitting, scale parameter, k.