Date of Award

6-1999

Degree Name

Master of Arts

Department

Psychology

First Advisor

Dr. Scott Kollins

Second Advisor

Dr. Wayne Fuqua

Third Advisor

Dr. Alan Poling

Access Setting

Masters Thesis-Open Access

Abstract

This experiment evaluated the effects of methylphenidate on sensitivity to reinforcement of children diagnosed with ADHD using matching law.

Four children (2 males and 2 females) between the ages of 6 and 10 who were previously diagnosed with ADHD completed easy math problems to earn tokens under four different variable-interval (VI) schedules of reinforcement presented in random order. The rate of completed math problems was plotted against the mean frequency of obtained reinforcers at each schedule value in tokens per minute. The data were fit to the following single-rate hyperbolic equation (Herrnstein, 1970): R = kr/r+r0.

Results show that the behavior of female participants was not well described by the matching law under MPH or placebo conditions, thus making any comparison between conditions uninterpretable. Under MPH conditions, the matching functions for both male subjects resulted in a higher asymptotic value (k), higher variance accounted for, and higher values of r0. In addition, it was demonstrated that MPH may alter the reinforcing value of different consequences.

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