EXPERIMENTAL ANALYSIS OF HUMAN BEHAVIOR BULLETIN 2000, 18, 6- 11 BRIEF REPORT ASSESSING BEHAVIORAL MOMENTUM IN HUMANS WITH MENTAL RETARDATION AND UNSTABLE BASELINES

Nevin described behavioral momentum by drawing an analogy between physical motion and behavioral persistence (Nevin, 1992; Nevin & Grace, 2000). In classical mechanics, the degree to which an opposing force will reduce the velocity of a moving body depends upon that body's momentum. Momentum is directly proportional to mass, and thus increasing mass increases resistance to change. Nevin suggested a parallel in the discriminated operant, with rate of responding analogous to velocity. According to the momentum analogy, the degree to which a disrupting event will reduce the rate of a response depends upon the behavioral momentum. Previous research indicates that the momentum of a discriminated operant may be directly related to the rate of reinforcement in the presence of the discriminative stimulus, and thus increasing reinforcer rate may increase behavioral "mass " and resistance to change. Behavioral momentum is typically assessed by measuring relative disruption in the components of multiple schedules with different obtained reinforcer rates. Disrupters are events that typically reduce response rates, and they may include procedures such as prefeeding, concurrently available alternative reinforcers, extinction, and so forth. Behavioral mass is indexed by the difference in response-rate reductions in the components during disruption, expressed as proportions of baseline rates. A behavioral momentum effect is shown by smaller reductions in the component with the higher rein