Abstract: | This meta-analysis investigated the strengths of the relationship between various types of motivations and accompanying future outcomes that individuals intend to change, based upon 337 effect sizes from 62 studies. Considerable variation exists within and between the effect sizes of the 14 types of motivations, ranging from a small negative effect size, r = −.13, I2 = 93.85% (k = 13), to a medium positive effect size, r = .38, I2 = 0.0% (k = 3). The following factors moderated some of the 14 summary effect sizes: (a) the type of assessment data (self-report vs. physical data); (b) the type of future outcomes (physical behavior, psychological state, and intellectual ability); (c) the use of a motivational intervention; (d) the use of a longitudinal design; and (e) the time period between the point that measured motivation and future outcomes. The moderating effects suggest that the effect size of motivations may fluctuate across various domains, while future outcomes may be almost unaffected or even affected negatively by particular types of motivations, although certain other types of motivations play positive roles. |