Skill acquisition is enhanced by reducing trial-to-trial repetition.

Developing approaches to improve motor skill learning is of considerable interest across multiple disciplines. Previous research has typically shown that repeating the same action on consecutive trials enhances short-term performance but has detrimental effects on longer term skill acquisition. However, most prior research has contrasted the effects of repetition only at the block level; in the current study we examined the effects of repeating individual trials embedded in a larger randomized block, a feature that is often overlooked when random trial orders are generated in learning tasks. With 4 days of practice, a "Minimal Repeats" group, who rarely experienced repeating stimuli on consecutive trials during training, improved to a greater extent than a "Frequent Repeats" group, who were frequently presented with repeating stimuli on consecutive trials during training. Our results extend the previous finding of the beneficial effects of random compared with blocked practice on performance, showing that reduced trial-to-trial repetition during training is favorable with regard to skill learning. This research highlights that limiting the number of repeats on consecutive trials is a simple behavioral manipulation that can enhance the process of skill learning. Data/analysis code and Supplemental Material are available at https://osf.io/p3278/.