The effects of exposure duration and luminance on the 3-dot hyperacuity task.

The 3-dot hyperacuity task was given to two subjects under three experimental paradigms: constant luminance, constant energy and constant duration. Hyperacuity was obtained under conditions (3 dots, 2 msec exposure) which rule out any significant temporal or spatial averaging. There was a clear threshold decrease in the constant luminance paradigm as exposure duration increased, no significant variations in threshold with the constant energy paradigm, as exposure duration varied and a U-shaped function in the constant exposure duration paradigm as luminance varied. It is concluded that what limits performance, at least for short exposure durations, is the total energy of the stimulus. The implications of the present results to the static and dynamic approaches to hyperacuity are discussed.