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.

Preference assessments were conducted for 4 individuals with developmental disabilities across conditions of (a) control, allowing equal access to all stimuli prior to the preference assessment; (b) deprivation, allowing no access to one stimulus for 48 hr prior to the assessment; and (c) satiation, allowing free access to one stimulus for 10 min immediately prior to the assessment. Deprivation resulted in increased preference, whereas satiation resulted in decreased preference compared to control conditions.

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 degree of response suppression was measured in 5-sec. intervals during a signal that was associated with electric shock. Four groups of 6 rats were tested with signals of fixed or random duration and with shocks that occurred at the end of the signal or at random times during the signal. In all cases, there was a transient effect of the onset of the signal, but thereafter, the 4 groups showed qualitatively different fear gradients. The magnitude of fear was closely related to the expected time to the next shock.

The effects of choice and no choice of reinforcer on the response rates of 3 children with autism were compared across single-operant and concurrent-schedule procedures. No consistent differences in responding between choice and no-choice components emerged during single-operant phases. During the concurrent-schedule phases, however, all participants had substantially higher rates of responding to the button that led to a choice among reinforcers than to the button that did not lead to choice.