Aprocedure in which stimuli with known reinforcing properties are presented on fixed-time or variable-time schedules completely independent of behavior. the discontinuing of the reinforcement of a previously reinforced behavior (i. e., responses no longer produce reinforcement.) a behavioral effect associated with extinction in which the behavior suddenly begins to occur after its frequency has decreased to its prereinforcement level or stopped entirely. a schedule for the delivery of noncontingent stimuli in which the interval of time from one delivery to the next randomly varies around a given time. the process by which behaviors maintained by automatic reinforcement are placed on extinction by masking or removing the sensory consequence. behaviors maintained with negative reinforcement are placed on when those behaviors do not produce a removal of the aversive stimulus. an increase in the frequency of responding when an extinction procedure is initially implemented. the relative degree to which operant behavior continues to occur during extinction.