Twenty-two studies were included in the review (n=76, of which 53 were classified as having ASD): 10 studies used CTD (n=36, 16 with ASD); and 12 studies used PTD (n=40, 37 with ASD).
CTD was effective in teaching targeted skills to most of the participants. Error percentages were the most consistently reported outcome. Based on seven studies the mean error percentage was 9.95 per cent errors to criterion (range 1.35 per cent to 32.5 per cent).
PTD was effective with all 37 participants from studies included in this review. Three studies reported mean error percentages giving an average mean error of 2.8 per cent (given variously in tables as 2.6 per cent and 2.7 per cent) errors towards criterion (range 0.3 per cent to 5.3 per cent). Nine studies reported maintenance data showing that acquired behaviours were maintained over time.
Errors to criterion were greater in patients receiving CTD (10 per cent) compared to patients receiving PTD (2.6 per cent). Transfer of stimulus control was faster using PTD (after four sessions) compared to CTD (after 5.5 sessions). Compared to other instructional procedures, the CTD procedure was more effective than the SLP procedure. The PTD procedure was more effective than SLP, LTM and visual fading procedures.