Effect of dot density on human and model Dmax.

<p>A. The value for Dmax derived from the raw direction discrimination performance data. Dmax is plotted as a function of dot density for each of the three observers. Open circle MC; open square SN; open diamond ST. Error bars show the 95% confidence interval for Dmax derived from the fitting procedure. B. Open diamonds show the Dmax values derived from the average performance of the three observers with the filled squares indicating the values of Dmax derived from the model results of direction discrimination performance as a function of displacement size. The error bars are as for the top panel. When error bars are not present, errors are smaller than the symbol size.