Fisk, G.D. & Haase, S.J. (2005). Unconscious perception or not? An evaluation of detection and discrimination as indicators of awareness. American Journal of Psychology, 118(2), 183-212.
Most investigations of unconscious perception employ a dissociation design in which an awareness variable (e.g., detection) is compared to a perceptual processing variable (e.g., identification or semantic priming). Unconscious perception is inferred when the awareness variable lacks sensitivity to the stimulus, but evidence of perceptual processing is still obtained. In the present experiments, the relationship between word identification and detection (Study 1) or discrimination (words v. nonwords; Study 2) was examined with a variety of techniques. In both experiments, dissociations suggestive of unconscious perception occurred when the data were examined with subjective threshold approaches, but these differences disappeared when the variables were compared with techniques derived from signal detection theory (SDT). Overall, these results do not provide compelling evidence in support of unconscious perception in subjective threshold paradigms. In addition, detection appears to be the most sensitive and appropriate task for assessing stimulus awareness, provided that several SDT assumptions are met.