Thirty-eight studies were included in the review (n=147): 36 single-subject research designs and two group experimental studies. Treatment integrity was reported in 14 studies and (where reported) was found to be high.
Social stories (six studies) had PND scores between 46.7% and 100% (mean 67.21%) and were deemed of questionable effectiveness. Peer-mediated interventions (nine studies) had PND scores between 35.09% and 100% (mean 60.69%) ande were deemed low to questionable effectiveness. Video modelling (11 studies) had PND scores between 50% and 100% (mean 84.25%), which was considered to be effective. Cognitive-behavioural training (three studies) had one study with a PND of 100%; effect sizes in one study ranged from 0.24 to 0.59 and in the other study ranged from 1.24 to 1.47. Other interventions (single studies) included pivotal research training, theory of mind, scripts and cue cards, picture exchange communication system (PECS) training and tactile prompting device.
Across the categories of interventions, 12 out of 36 studies reported maintenance effects with PND scores from 38% to 100% (mean 78.5%). Nine studies reported generalisation effects of the intervention with PND scores that ranged from 40% to 100% (mean 80.95%). Nine studies reported follow-up data with PND scores that ranged from 60% to 100% (mean 92.15%).