Mirror-drawing skill in children with specific language impairment: Improving generalization by incorporating variability into the practice session.

This study aimed to investigate the procedural deficit hypothesis (PDH) in children with specific language impairment (SLI) by using a mirror-drawing task, a sensorimotor adaptation paradigm that does not involve sequence learning and has never before been used in SLI. A total of 30 school-aged children with SLI matched to 30 typically developing (TD) control children had to trace several figures seen only in mirror-reversed view in two practice sessions separated by a one-week interval. Two practice conditions were compared: a constant condition in which children had to trace the same figure throughout the learning trials, and a variable one in which they had to trace different figures in each trial. The results revealed a similar learning pattern between SLI and TD children in both practice conditions, suggesting that initial learning for a non-sequential procedural task is preserved in SLI. However, the children with SLI generalized the mirror-drawing skill in the same way as the TD children only if there was variability in the way the material was trained (variable practice). No significant schedule effects were observed in the control group.