Behavioral Choice, Momentum, and Inhibition in Mental Retardation
The behavior of individuals with mental retardation often seems relatively insensitive to environmental feedback. It may be described as rigid, inflexible, and perseverative. Inflexibility is evident in overt behavior and in aspects of cognition. People with intellectual disabilities, for example, are slower than unimpaired individuals to shift their bases for responding in a variety of discrimination learning and classification paradigms. This research examines the interrelated topics of sensitivity to reinforcing consequences and behavioral flexibility.
We have implemented a computer-based assessment procedure that yields quantitative analyses of sensitivity to reinforcement contingencies in mental retardation. Test procedures are embedded in a computer game that can be configured appropriately for individuals across the range of mild to severe mental retardation. Results show individual differences in sensitivity to frequency and magnitude of reinforcement, both within and between subjects (Dube & McIlvane, 2002a). These findings indicate the need for reinforcer assessments that evaluate not only preference, but also rate and magnitude parameters. They also illustrate the potential for quantitative behavior-analytic methods to contribute to the study of motivational processes in individuals with mental retardation (Dube & McIlvane, 2006).
We have also completed several studies of behavioral momentum, which is the relation between stimulus control, reinforcer rate, and behavioral flexibility (which may also be viewed as persistence, or resistance to change). The results of one study using laboratory models of special-education tasks demonstrated that persistence depends on reinforcer rate (Dube & McIlvane, 2001). Another study developed a new testing procedure for more efficient evaluation of momentum effects. Typical procedures require steady-state behavioral baselines; the new procedure allows testing in situations with variable response rates (Dube, Mazzitelli, Lombard, & McIlvane, 2000). A full experimental test of the new procedure has shown that reinforcer rate effects are generally found in individuals with mental retardation (Dube & McIlvane, 2003).
We have also investigated momentum effects in discrimination reversal learning (Dube & McIlvane 2002b; McIlvane & Dube, 2000). Lower reinforcement rates during acquisition tend to produce greater flexibility, as shown by fewer errors in within-session reversals. Flexible reversal learning may be an important prerequisite for conditional-discrimination tasks such as matching to sample.
For application, one study has shown that the treatment of stereotypic behavior by response-independent reinforcement procedures (sometimes referred to as noncontingent reinforcement or environmental enrichment) may decrease the rates of such behavior but also increase its persistence (Ahearn et al., 2003). A recently completed study found that maladaptive behavior was more resistant to extinction following higher rates of reinforcement (paper in preparation).
Publications
Ahearn, W. H., Clark, K. M., Gardenier, N. C., Chung, B. I., & Dube, W. V. (2003). Persistence of stereotypy: Examining the effects of external reinforcers. Journal of Applied Behavior Analysis, 36, 439-447.
Dube, W. V., Mazzitelli, K., Lombard, K. M., & McIlvane, W. J. (2000). Assessing behavioral momentum in humans with mental retardation and unstable baselines. Experimental Analysis of Human Behavior Bulletin, 18, 6-11.
Dube, W. V. & McIlvane, W. J. (2001). Behavioral momentum in computer-presented discriminations in individuals with severe mental retardation. Journal of the Experimental Analysis of Behavior, 75, 15-23.
Dube, W. V. & McIlvane, W. J. (2002a). Quantitative assessments of sensitivity to reinforcement contingencies in mental retardation. American Journal on Mental Retardation, 107, 136-145.
Dube, W. V. & McIlvane, W. J. (2002b). Reinforcer rate and stimulus control in discrimination reversal learning. The Psychological Record, 52, 405-416
Dube, W. V., McIlvane, W. J., Mazzitelli, K., & McNamara, B. (2003). Reinforcer rate effects and behavioral momentum in individuals with developmental disabilities. American Journal on Mental Retardation, 108, 134-143.
Dube, W. V. & McIlvane, W. J. (2006). Behavior-analytic experimental strategies and motivational processes in persons with mental retardation. In H. Switzky, L. Hickson, & R. Schalock (Eds.), International review of research in mental retardation, Vol. 31: Mental retardation, personality, and motivational systems (pp. 261-288). San Diego, CA: Academic Press.
McIlvane, W. J. & Dube, W. V. (2000). Behavioral momentum and multiple stimulus control topographies [Commentary]. Behavioral and Brain Sciences, 23, 109.