Murray, L. K., & Kollins, S. H. (2000).
Effects of methylphenidate on sensitivity to reinforcement in children diagnosed with attention deficit hyperactivity disorder: An application of the matching law.
Journal of Applied Behavior Analysis,
33, 573-591.
The behavior of children diagnosed with attention deficit
hyperactivity disorder (ADHD) has been hypothesized to be the
result of decreased sensitivity to consequences compared to
typical children. The present study examined sensitivity to
reinforcement in 2 boys diagnosed with ADHD using the matching
law to provide more precise and quantitative measurement of this
construct. This experiment also evaluated the effects of
methylphenidate (MPH) on sensitivity to reinforcement of children
with ADHD. Subjects completed math problems to earn tokens under
four different variable-interval (VI) schedules of reinforcement
presented in random order under both medicated and nonmedicated
conditions. Results showed that, in the medicated condition, the
matching functions for both subjects resulted in higher
asymptotic values, indicating an overall elevation of behavior
rate under these conditions. The variance accounted for by the
matching law was also higher under the medicated conditions,
suggesting that their behavior more closely tracked the changing
rates of reinforcement while taking MPH compared to placebo.
Under medicated conditions, the reinforcing efficacy of
response-contingent tokens decreased. Results are discussed with
respect to quantifying behavioral changes and the extent to which
the drug interacts with prevailing contingencies (i.e., schedule
values) to influence behavioral variability.
DESCRIPTORS: _attention deficit hyperactivity disorder,
methylphenidate, sensitivity to reinforcement, matching law