Background: Motor impairment is considered as one of the main features of autism and Asperger syndrome. The aim of this study was to investigate the explicit motor-sequence learning in children with autism spectrum disorder (ASD) and its consolidation after 24 hours.

Materials and Methods: In this clinical trial study, 15 boys with ASD and 16 matched healthy controls were selected using the autism spectrum screening questionnaire among the elementary schools in Najafabad (Isfahan, Iran). Participants in both groups performed the serial reaction time task in 10 blocks at the first day and 2 blocks after 24 hours.

Results: The mean and standard deviation of explicit learning speed through 8 regular blocks in the first day was 1.5±0.405 in the ASD group and 1.14±0.29 in healthy controls. There was a significant difference in the explicit learning speed between the two groups which indicated an explicit learning deficit in the ASD group (P=0.009). Moreover, there was a significant difference between the two groups for explicit learning speed mean in the first and second days of the experiment (ASD: 1.295±0.31 healthy controls: 1.06±0.21, P=0.046) suggesting a defect in consolidation of the explicit motor-sequence learning in the ASD group.

Conclusion: Defect in the explicit motor-sequence learning and its consolidation in the ASD group may be due to the left hemisphere dysfunction, which is specialized for explicit motor learning, and confirms the motor impairments in individuals with ASD.