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/ . NEW & NOTEWORTHY Numerous studies have shown that performing different subtasks across consecutive blocks of trials enhances learning. We examined whether the same effect would occur on a trial-to-trial level. Our Minimal Repeats group, who primarily responded to different stimuli on consecutive trials, learned more than our Frequent Repeats group, who frequently responded to the same stimulus on consecutive trials. This shows that minimizing trial-to-trial repetition is a simple and easily applicable manipulation that can enhance learning.

13Developing approaches to improve motor skill learning is of considerable interest 14 across multiple disciplines. Previous research has typically shown that repeating the same 15 action on consecutive trials enhances short-term performance, but has detrimental effects on 16 longer term skill acquisition. However, most prior research has contrasted the effects of 17 repetition only at the block level; here we examined the effects of repeating individual trials 18 embedded in a larger randomized block a feature that is often overlooked when generating 19 random trial orders in learning tasks. With four days of practice, a "Minimal Repeats Group", 20 who rarely experienced repeating stimuli on consecutive trials during training improved to a 21 greater extent than a "Frequent Repeats Group", who were frequently presented with repeating 22 37