Myrna E. Libby

A Comparison of Most-to-Least and Least-to-Most Prompting on the Acquisition of Solitary Play Skills

Two studies are presented in which common prompting procedures were evaluated while teaching children with autism to build Lego® play structures. In the first study, most-to-least (MTL) and least-to-most (LTM) prompting were compared. All participants learned to build the play structures when the teacher used MTL, which was associated with fewer errors than LTM. Nonetheless, three participants learned more quickly with LTM. This finding suggests that MTL may prevent errors, but it sometimes slows learning. The second study compared LTM to MTL without and with a delay (MTLD). MTLD provided an opportunity for the child to independently initiate responding but still minimized the likelihood of errors. Results showed that acquisition was nearly as rapid when the teacher used MTLD as LTM but it produced fewer errors than LTM. Best practice guidelines for choosing prompting procedures are proposed.

A Procedure for Identifying Precursors to Problem Behavior.

We describe a procedure for differentiating among potential precursor responses for use in a functional analysis. Conditional probability analysis of descriptive assessment data identified three potential precursors. Results from the indirect assessment corresponded with those obtained from the descriptive assessment. The top-ranked response identified as a precursor according to the indirect assessment had the strongest relation according to the probability analysis. When contingencies were arranged for the precursor in a functional analysis, the same function was identified as for target behavior, supporting the utility of indirect and descriptive methods to identify precursor behavior empirically.

THE EFFECTS OF REINFORCER CHOICE ON RATES OF CHALLENGING BEHAVIOR AND FREE OPERANT RESPONDING IN INDIVIDUALS WITH SEVERE DISABILITIES

A multielement design was used to evaluate the eAects of three reinforcement conditions on the free-operant and challenging responses of two individuals with severe disabilities. Preference assessments identified three stimuli that could function as reinforcers for each participant. Reinforcers were delivered on a variable ratio schedule for a free-operant response. In the participant-selected condition, each reinforcer delivery consisted of placing an array of three diAerent stimuli in front of the participant, who was allowed to select one. In the constant condition, each reinforcer delivery consisted of placing an array of three identical stimuli in front of the participant. Within each session the three stimuli were held constant, but varied across sessions. In the experimenter-selected condition, each reinforcer delivery consisted of an array of three identical stimuli being placed in front of the participant. Within each session, the three stimuli were presented in an order predetermined by the experimenter such that, on average, each stimulus was available every third reinforcer delivery. For both individuals, the participantselected condition resulted in lower average rates of challenging responses and slightly higher average free-operant response rates. No diAerences in responding were noted between the constant condition and the experimenter-selected condition. #1998 John Wiley & Sons, Ltd. Individuals with severe disabilities frequently require dense reinforcement for both skill acquisition and the reduction of challenging behaviors. Finding and maintaining eAective reinforcers are essential for eAective intervention. Most reinforcement procedures used in applied settings are derived from basic animal research in which establishing operations, such as deprivation, were manipulated (Michael, 1982). Although there is some evidence that manipulating establishing operations can aAect responding in individuals with developmental disabilities

Functional analysis and treatment of screaming in a young girl with severe disabilities

Descriptive assessments suggested that the screaming of a 6-year-old girl with autism and severe mental retardation was maintained by automatic reinforcement. During two phases of a functional analysis, differentiation across experimental conditions was not achieved. Levels of screaming decreased across sessions in all experimental conditions. A time-out treatment procedure led to a rapid decrease in screaming. Copyright

A COMPARISON OF PROCEDURAL VARIATIONS IN TEACHING BEHAVIOR CHAINS: MANUAL GUIDANCE, TRAINER COMPLETION, AND NO COMPLETION OF UNTRAINED STEPS

We compared variations for teaching a sequence of responses through forward chaining. Seven children who had been diagnosed with autism participated in a comparison of teacher completion (TC) of steps beyond the training step and manually guiding the student (SC) to complete steps beyond the training step. A no-completion (NC) condition, in which the steps beyond the training step were not completed, was added to the comparison with 4 of the participants. Results showed that learning occurred with all procedures, although 5 participants acquired the chains most efficiently in the SC condition and the other 2 learned most efficiently in the TC condition. Of the participants for whom an NC condition was included, the tasks were acquired with the shortest average session length and total training time. Despite the potential benefits of TC and SC procedures, NC is a viable option and may be preferable for some students.