Skinner built a small, sound-proof chamber that provides an experimentalspace within which an animal can be studied (Nye, 1992). In this box, an animalcan be isolated from interferring influences and subjected to specificconditions. The operant behavior studied is lever pressing by a rat. Thechamber contains only a bar (or lever) and a small tray outside the box. Thetray holds the food pellets that are dropped into the tray when the bar ispressed under certain conditions.