A meta-analysis on unconscious thought effects

A meta-analysis was performed on the unconscious thought effect (UTE). All available published and unpublished data on unconscious thought were included. Our aims were to provide a statistically robust estimate of the effect size of the UTE, to identify significant moderators, and to discuss possible underlying processes of the UTE. To assess the UTE, performance of participants thinking unconsciously was compared to participants thinking consciously, and to immediate decision makers. Across a total of 92 studies, the overall aggregated effect size was g = .224, with a 95% confidence interval from .145 to .303. This result provides strong support for the existence of the UTE. However, as estimated from a random-effects model, about 66% of the variance in effect sizes was attributable to systematic differences between studies. This result indicates that although the UTE is a real effect, it does not always occur. Several moderators were identified that help to explain the mixed results across various studies. The findings are discussed with regard to the boundary conditions and potential underlying processes of the UTE.