The modified Geller and Seifter conflict procedure, involves a multiple schedule of reinforcement. In one schedule (signaled by a tone or light), responding is reinforced at irregular intervals (Variable Interval (VI)). In the second schedule (signalled by a different signal), every response is reinforced (Fixed Ratio (FR)) or (Continuous Reinforcement (CRF)) while also punished by the delivery of a brief, inescapable electric shock. Untreated trained animals show stable and relatively high rates of responding during the VI, but suppressed responding during the punishment component. The ability to antagonize response suppression in the punished periods is considered a good predictor for clinical efficacy of anxiolytics.