The responses of individual subjects are also well-fit by the functional form of the theoretically obtained bound on memory performance. Top two panels: the quality of fit (weighted squared error of fit) as a function of the two parameters of the theory (dark blue = best fit; dark red = worst fit), for each of the 10 subjects in the study. Middle two panels: The quality of fit along the valley defined by the dark blue area in the top two panels, plotted as a function of , for each of the 10 subjects. Most subjects have an optimal value of . The two outliers (subjects 7 and 8, with and , respectively, have rather flat fit quality along the entire valley, as a function of , and thus other values of produce very similar fit quality.) Bottom two panels: Individual subject performance (circles: mean-squared error averaged across trials; error bars are the across-trial SEM) as a function of storage interval duration, for different item numbers (1, 2, 4 and 6 items, black, blue, cyan and green, respectively). Solid curves: fits from the theoretical bound on performance (minimum weighted squared error).