Biomedical subjects
Publications and source records attributed to M R Dixon.
The present study examined the possible function of inappropriate verbal behavior of an adult man who had been diagnosed with both mental retardation and psychosis. Results of a functional analysis indicated that inappropriate verbal utterances were maintained by attention. An intervention consisting of the differential reinforcement of appropriate verbal behavior effectively reduced the inappropriate behavior.
This study examined the use of a progressive-delay schedule of reinforcement to increase self-control and decrease disruptive behavior in children with autism. When initially given the choice between an immediate smaller reinforcer and a larger delayed reinforcer, all participants chose the smaller reinforcer. When access to the larger reinforcer required either no activity or engaging in a concurrent task during the delay, all participants demonstrated both self-control and preference for a response requirement. Disruptive behavior decreased during delays that required a concurrent task compared to sessions without an activity requirement.
The present study examined the temporal characteristics of play exhibited by recreational slot machine players. 12 women (M = 24 yr., range 22-28) played a computerized version of a slot machine with probability of payoff, i.e., a winning spin, ranging from .2 to .6. Intertrial intervals or the time between the termination of one trial to the initiation of the next trial varied within subjects as a function of wins and losses. Winning trials were associated with larger intertrial intervals and losing trials with smaller intertrial intervals for 10 of the 12 women. No differences were found across probability levels between subjects. Results are discussed in terms of the post-reinforcement pause that occurs on specific schedules of reinforcement.
OBJECTIVE: To test the hypothesis that a decreased unipedal stance time (UST) is associated with a history of falling among older persons. DESIGN: Fifty-three subjects underwent a standardized history and physical examination and three trials of timed unipedal stance. SETTING: The electroneuromyography laboratories of tertiary care Veterans Administration and university hospitals. SUBJECTS: Ambulatory outpatients 50 years and older referred for electrodiagnostic studies. OUTCOME MEASURES: UST and fall histories during the previous year. RESULTS: Twenty subjects (38%) reported falling. Compared with the subjects who had not fallen, those who fell had a significantly shorter UST (9.6 [SD 11.6] vs 31.3 [SD 16.3] seconds, using the longest of the three trials, p < .00001). An abnormal UST (<30sec) was associated with an increased risk of having fallen on univariate analysis and in a regression model (odds ratio 108; 95% confidence interval 3.8, >100; p < .007). The sensitivity of an abnormal UST in the regression model was 91% and the specificity 75%. When UST was considered age was not a predictor of a history of falls. CONCLUSIONS: UST of <30sec in an older ambulatory outpatient population is associated with a history of falling, while a UST of > or = 30sec is associated with a low risk of falling.
This study examined the use of a progressive delay procedure combined with verbal mediation to teach self-control to children with attention deficit disorder. Results showed that when participants were initially given the choice between an immediate smaller reinforcer and a larger delayed reinforcer, all participants chose the smaller reinforcer. When slight delays to obtain a larger reinforcer were instated in conjunction with intervening verbal activity, all participants demonstrated self-control regardless of the content of the verbal activity.
The present study examined the use of a progressive delay procedure to teach self-control to two groups of dually diagnosed adults. When given a choice between an immediate smaller reinforcer and a larger delayed reinforcer, both groups chose the smaller reinforcer during baseline. During treatment, progressive increases in work requirements for gaining access to a larger reinforcer resulted in both groups selecting larger delayed reinforcers. The results are discussed with respect to increasing cooperative work behavior and self-control.
The present paper describes a computerized slot machine simulation designed to examine many of the potential variables involved in gambling behavior. This program was created in Visual Basic Version 6.0 and is designed to run on any Windows 95 or higher equipped computer. The program allows for experimenter manipulation of probabilities of payoffs, visual display of potential winning symbols, exact sequences of wins and losses, as well as pose run time questions to the subject on prespecified trials. The program records data on a trial-by-trial basis to a text file for easy importation into many data analysis and statistical programs. Conceptual and experimental questions that may be addressed with the described program are also discussed.
The present study evaluated a technique for teaching self-control and increasing desirable behaviors among adults with developmental disabilities. Results showed that when participants were initially given the choice between an immediate smaller reinforcer and a larger delayed reinforcer, all participants repeatedly chose the smaller reinforcer. Concurrent fixed-duration/progressive-duration reinforcement schedules then were introduced in which initially both the smaller and larger reinforcers were available immediately. Thereafter, progressively increasing delays were introduced for the schedule associated with the larger reinforcer only. When initial short-duration requirements for access to the larger reinforcer were gradually increased, participants repeatedly selected the larger reinforcer, thereby demonstrating increased self-control.
Risk-taking behavior occurs when an individual chooses to engage in a game of chance. Although the outcomes of these games are completely random, many individuals believe that they can exercise some control over the outcomes. The present study examined the extent to which five undergraduate roulette players would pay additional money for opportunities to engage in an illusory activity that had no influence on the game's outcome, i.e., choosing random numbers rather than having the experimenter choose them. All five subjects engaged in this type of activity and the extent to which they did was linearly related to the player's winnings. These findings may suggest why people continue to gamble when the odds of winning are against them.