Constant time delay with discrete responses: a review of effectiveness and demographic, procedural, and methodological parameters.

Constant time delay, a variation of progressive time delay, is a response prompting strategy designed to provide and remove prompts in a systematic manner on a time dimension. Constant time delay has two defining characteristics: (a) initial trials involve presentation of the target stimulus followed immediately by delivery of a controlling prompt; and (b) on all subsequent trials, the target stimulus is presented, a response interval of a fixed duration is delivered, the controlling prompt is provided, and a second response interval is delivered as needed. Reports of 36 studies using the constant time delay procedure with discrete behaviors were identified and analyzed. The results are described in terms of demographic variables (i.e., the types of subjects, settings, behaviors, instructors, and instructional arrangements), and the procedural parameters of the strategy. The effectiveness of the strategy and the outcome measures are summarized. Finally, the methodological adequacy of the constant time delay research is examined. Implications for practice and for further research are presented.