A unified model for the combined temporal and spatial Broca-Sulzer effect

A briefly pulsed light is brighter than a pulse of longer duration. For a brief flash of fixed duration and small area, enlarging a target results initially in an increase in brightness. Beyond some critical area, the target dims with further increases in size. These two phenomena are the temporal and the spatial Broca-Sulzer effect respectively. Each effect can be modeled using a generalization of the Hartline-Ratliff equation. The resulting analysis produces a mathematically unified treatment of both effects.