Meta-analyzing enhanced expectancies on motor learning: positive effects but methodological concerns

The OPTIMAL theory of motor learning predicts enhanced expectancies facilitate learning. This meta-analysis investigated this prediction by quantifying effect sizes from studies manipulating feedback after good trials, comparative feedback, perceived task difficulty, conceptions of ability, self-modeling, or extrinsic rewards, and assessing learning. After searching databases, 48 studies met inclusion criteria for quantitative analysis. Fifty-six effect sizes were calculated from performance differences between enhanced expectancies and neutral/diminished expectancies groups at delayed retention tests. Results revealed a Hedges’ g = 0.54 (95% CI [0.38, 0.69]) that may be overestimated due to small-study effects and underpowered studies. Moderator analyses revealed feedback after good trials, comparative feedback, perceived task difficulty, and conceptions of ability manipulations significantly improved learning. Few studies used other manipulations, precluding reliable estimates of their effects. Further, significant effects of enhanced expectancies were shown for children/adolescents, young adults, and older adults. Few studies examined special populations, preventing a reliable effect estimate. Finally, the effect of enhanced expectancies on learning was not affected by type of comparison group (neutral/diminished expectancies). Findings suggest enhanced expectancies may facilitate motor learning, consistent with OPTIMAL theory, but pre-registered/registered reports and more powerful studies should be conducted to confirm the effect and estimate its size more accurately.