External focus and autonomy support: two important factors in motor learning have additive benefits.

We examined whether the combination of two factors that have consistently been found to enhance motor learning - an external focus (EF) of attention and autonomy support (AS) - would produce additive benefits. Participants practiced throwing with their non-dominant arm. In a 2×2 design, they were or were not asked to focus externally (i.e., on the target), and were or were not given a choice (autonomy support). The latter involved choosing 2 5-trials blocks during practice on which they used their dominant arm. All four groups - EF/AS, EF, AS, and C (control) - completed a practice phase consisting of 60 trials. The distance to the target (bull's eye) was 7.5m. One day later, participants performed retention (same target distance) and transfer tests (8.5m). Both external focus instructions and autonomy support enhanced retention and transfer performance. Importantly, the combination of these factors resulted in additive learning advantages. The EF/AS group showed the greatest throwing accuracy, and the EF and AS groups outperformed the C group. In addition, self-efficacy measured after practice and before retention and transfer was increased by both factors. Thus, promoting an external focus of attention and supporting learners' need for autonomy seem to independently influence learning.