The operant chamber configuration in our laboratory includes a stainless-steel rod floor (A), graduated drinking sipper attached to a stationary mount (B), food receptacle (C), food pellet dispenser (D), lickometer circuit (E) with electrical connections (dotted gray lines) to metal sipper and rod floor, and house light (F). Apparatus is positioned within a sound-attenuating cabinet and a fan is used to ventilate the chamber and mask external noise. Iterations to this configuration and its components are discussed in the text.