Both participants attended to the video during 100% of time samples across all sessions in both conditions. Imitation of actions during simultaneous video modeling is depicted in Figure 1. The final mean of each phase is calculated based on the last three data points and is reported throughout the results section to provide a measure of final level of acquisition. Data are not provided for imitation of actions during video priming because play sets were not available during video priming training sessions. Mark’s imitation of actions (top panel) gradually increased as the time delay was increased until he was imitating all 10 actions during each video model in both conditions. While watching the video with the Gen 1 House, he first imitated 7 actions and then 10 actions during the each of the last two sessions. Erin (bottom panel) also gradually began to imitate more as the time delay was increased, reaching a mean of 8.33 actions imitated per session for the last three sessions.