Abstract
Imagery is often proposed to be an effective way to enhance the physical performance of athletes and exercisers. A meta-analytic evaluation of the extant literature was conducted to provide an objective assessment of the veracity of that proposal. Previous metaanalyses in the area have reported significant benefits of imagery, although the most recent of these was conducted more than 15 years ago, since when much additional research has been conducted. Search procedures, which included a systematic trawl of 14 electronic databases and manual searches of 12 relevant journals, identified a total of 205 relevant articles for detailed review. Of these, 108 studies met the inclusion and exclusion criteria and were included in the meta-analysis. Overall, 291 effects from 4,220 participants were derived from the studies. Using a random effects model, weighted mean effects and moderating variables were assessed via the Comprehensive Meta-Analysis software. The overall weighted mean effect (d = 0.53) indicated that imagery is associated with significant benefits to performance in sport and exercise. This moderate beneficial effect is similar to those reported in previous metaanalyses. Several moderating variables were identified. Males derive greater benefits from imagery (d = 0.52) than females (d = 0.36). Experienced participants derive greater benefits from imagery (d = 0.52) than novices (d = 0.44). Cognitive tasks, such as remembering complex routines, were enhanced more by imagery (d = 0.98) than strength tasks (d = 0.36) and motor tasks (d = 0.46). Imagery research published in Tier A journals reported larger effects (d = 0.95) than in Tier B journals (d = 0.63), Tier C journals (d = 0.42), and unpublished research (d = 0.19). The present findings have strengthened the evidence base for the use of imagery in sport and exercise domains. Used appropriately, imagery is typically associated with significant performance benefits. Given the larger effects reported in Tier A journals, where it may be assumed that tighter control of potential confounds has occurred, the true benefits of imagery may be greater than suggested by the overall effect found in the present metaanalysis.