Behavioral Momentum: Translational Research in Intellectual and Developmental Disabilities
Dube, William V., Ahearn, William H., Lionello-DeNolf, Karen, McIlvane, William J., The Behavior Analyst Today
During Nancy Neef's tenure as editor of the Journal of Applied Behavior Analysis, there was an increasing trend in the number of articles in that journal that sought to establish a connection between basic and applied research (Wacker, 1996). Wacker (1996) explicitly pointed out the "need for studies that bridge basic and applied research," the trend continued during his term as JABA's editor, and one began to hear the term "bridge study" with increasing frequency among behavior analysts. Now, over 12 years later, the importance of translational research is almost universally acknowledged within our field (e.g., McIlvane et al., in press). Such research--occupying a conceptual midpoint between basic research and applied research--has become a priority at the highest levels of science and medicine, for example, as seen in the establishment of the National Institutes of Health new Clinical and Translational Science Award (e.g., Morrison, 2008).
The Behavior Analyst Today (BAT) was "founded as a newsletter for master level practitioners ... [and] has evolved to being a primary form of communication between researchers and practitioners, as well as a primary form of communication for those outside behavior analysis" (BAT, 2004). For this reason, the intended audience for this paper is the practitioner interested in learning about the current status of translational research in behavioral momentum as a foundation for considering ways in which behavioral momentum theory may--or may not--be relevant to clinical issues. This paper will provide a selective review of that translational research, with an emphasis on human populations with intellectual and developmental disabilities (IDD). We will describe some of the ways in which momentum theory, arising in the basic research laboratory with nonhuman animals, has been shown to be applicable to the behavior of humans with IDD.
Nevin's behavioral momentum theory (Nevin, 1992, Nevin & Grace, 2000) makes an analogy between the relationships described in the physics of motion and the measurement of response strength. In classical mechanics, the momentum of a moving body is defined as the product of its velocity and mass. Nevin (1992) suggested a parallel in behavior. Rate of responding is analogous to velocity, and resistance to change analogous to mass. Resistance to change refers to the persistence of behavior in the face of some perturbing force or operation (e.g., distraction), and this behavioral analogue of mass is positively related to the overall level of reinforcement signaled by the stimuli that define the context in which the behavior occurs.
Consider a basketball and a bowling ball rolling down an inclined plane at equal speeds. Although velocities are equal, the force necessary to decelerate the bowling ball will be greater because of its greater mass; the bowling ball is more resistant to change. Now consider two operant responses, controlled by different discriminative stimuli A and B, but occurring at the same rate (velocity). According to behavioral momentum theory, if the historical level of reinforcement for the response controlled by stimulus A is greater than that for the response controlled by stimulus B, then response A will be more resistant to change than response B.
Basic Laboratory Research with Nonhuman Animals: Two Examples
We will begin by briefly describing two representative experiments from the basic research laboratory. These experiments illustrate a commonly used arrangement to study behavioral momentum, here designated as the multiple-schedule disrupter paradigm. We will use them to make three points that are important for evaluating the translational research to be discussed below: (a) In the basic research laboratory, resistance to change is assessed by relative measures; (b) given behavior in two contexts with different characteristic levels of reinforcement, behavior in the richer context will be more resistant to change; and (c) resistance to change is determined by the stimulus-reinforcer relations of the reinforcement contingencies. …