Figure 6.

The top panel shows the percentage duration of arranging and ordering of furniture and the percentage duration of item engagement during Christie's treatment evaluation. BL  =  baseline, MI  =  matched items, EXT  =  extinction, Sr⁺ for ENG  =  reinforcement contingent on item engagement; the asterisk indicates the point at which separate play skills training was conducted (between Sessions 44 and 45). Letters in the teacher implementation phase represent sessions conducted by different teachers (Teachers A, B, and C).