EXPRESS: Massed practice improves learning of serial motor skills.

Memory encompasses the ability to encode, store, and consolidate information. Temporal spacing between events can influence information processing in working memory and impact memory consolidation. The effects of intertrial spacing on working memory can be tested by manipulating practice distribution. However, the effects of spacing of practice on serial motor skill learning remain unknown. This study manipulated two different inter-trial intervals when learning a serial motor skill. We recruited 30 children, mean age 9.4 ± 0.8 years, with no prior experience in the task of sequentially pressing four keys on a computer numeric keypad. Participants were randomly assigned to either a massed practice condition with a 2-second inter-trial interval or a distributed practice condition with a 30-second inter-trial interval. After 24 hours, retention tests were conducted in both massed and distributed conditions. We found that a short inter-trial interval promoted better memory consolidation and learning in both retention conditions, with massed practice demonstrating greater consistency than distributed practice in the distributed retention test. Furthermore, the specificity of practice effect on learning was not observed. These findings suggest that shorter inter-trial intervals enhance memory consolidation and improve serial motor skill learning. We propose a different theoretical framework based on Decay Theory to explain the role of practice distribution in memory consolidation and learning.