Critical importance of stimulus unawareness for the production of subliminal psychodynamic activation effects: a meta-analytic review.

Meta-analysis that assessed the magnitude of behavior change produced by subliminal vs. supraliminal drive-related stimuli was performed on all subliminal psychodynamic activation (SPA) studies that employed both types of stimuli (N of studies = 11, N of subliminal-supraliminal comparisons = 43). The analysis revealed that subliminal presentation of drive-related stimuli produced significantly stronger effects on behavior than supraliminal presentation of the same stimuli. Stimulus content, type of outcome measure, and subject characteristics all influenced the magnitude of subliminal-supraliminal response differences. These results support Silverman's (1983) hypothesis that drive-related stimuli must be presented subliminally in order to produce SPA effects. Furthermore, given the pattern of subliminal-supraliminal effect sizes obtained, a partial cue hypothesis of SPA effects is not tenable. Implications of these findings for research that examines the restricting effects of awareness on responding to drive- and affect-related stimuli are discussed.