A space designed to minimise interference from stimuli (e.g., laboratory noises) irrelevant to experimental conditions, and including devices for recording behaviour (see OPERANDUM) and presenting stimuli. In typical chambers, stimulus sources include mechanisms for delivering reinforcers (e.g., food dispensers); discriminative-stimulus sources (e.g., speakers for presenting auditory stimuli; lamps or projectors for presenting visual stimuli); aversive-stimulus sources (e.g., see SHOCK); a houselights which provides general illumination; feedback devices, which produce stimuli such as clicks after each response; and auditory sources that mask outside noises (often a fan that provides masking noise along with ventilations)