Which law describes the relationship of a stimulus area that is below the threshold for spatial summation?

Rico's Law addresses the phenomenon of spatial summation and is specifically applicable to stimuli that are below the threshold level for perception. This law suggests that visual perception can be enhanced by the summation of multiple stimuli in proximity, even when those individual stimuli themselves do not reach the absolute threshold for detection. In essence, it emphasizes how overlapping or closely presented stimuli can collectively contribute to perception in ways that a single stimulus cannot.

In contrast, Weber's Law pertains to the just noticeable difference (JND) in relation to the intensity of the initial stimulus, highlighting a proportional relationship rather than spatial metrics. The Dowling-Rushton Law primarily relates to the relationship of stimulus intensity and perceived brightness, and DeVries-Rose Law is concerned with the changes in visual sensitivity in response to stimulus intensity, typically at thresholds for detection rather than below them. Thus, Rico's Law stands out by specifically outlining the threshold dynamics for spatial summation of stimuli.