Activity level as a function of hunger.

Abstract
Using a photo-electric cell activated by interruption of a light beam bisecting the living cage of a rat, the relation between activity (in terms of number of transverse crossings of this beam per half-hour period) and time-since-feeding was investigated for food deprivations of 0, 12, 24, and 48 hrs. The curve relating activity (y) to deprivation (x) was found to be a monotonically increasing, negatively accelerated one within the limits of deprivation investigated.