Unconscious perception at the objective detection threshold exists

Abstract

Does unconscious perception at the objective detection threshold (ODT) exist? In this reply, formal meta-analyses of previously narratively reviewed evidence (Snodgrass, Bernat, & Shevrin, 2004) provide strong evidence for large, reliable unconscious perceptual effects, and further strengthen previous conclusions for their ODT status. These meta-analyses dispel general concerns that ODT effects are small, unreliable, or susceptible to file drawer concerns (cf. Reingold, 2004). Furthermore, the specific objections (Holender & Duscherer, 2004) to individual ODT effects are refuted, and objections to our proposed solutions to the exhaustiveness, exclusiveness, and null sensitivity problems (Haase & Fisk, 2004; Reingold, 2004) are shown to be inapplicable, contradicted by the available evidence, or both. Accordingly, the strong evidence for ODT effects, taken together with the nonmonotonic relationship, contradicts the single-process conscious perception model (e.g., Holender & Duscherer, 2004) and provides stronger evidence for unconscious perception than hitherto available. This research was undertaken as part of a research program on conscious and unconscious processes in the Ormond and Hazel Hunt Memorial Laboratory, directed by H.S. and supported by gifts from Robert Berry and the Smart Family Foundation. Special thanks to Mark Van Selst and Philip Merikle for making their raw data available. Correspondence concerning this article should be addressed to M.

Subliminal unconscious conflict alpha power inhibits supraliminal conscious symptom experience

“…Subsequent research revealed that at the ODT different things happen than at the supraliminal threshold. For example, in a series of replicated studies (Snodgrass et al, 1993a,b, 2004a,b), Snodgrass discovered inhibitory processes at the ODT that were a function of individual differences, findings quite germane to our current study. These effects were based on standard cognitive tasks (e.g., word choices).…”

“…For example, mean 1 could be larger than mean 2, but this says nothing about whether scores in condition 1 are correlated with scores in condition 2. We have previously documented in our review (Snodgrass et al, 2004a), extremely subliminal conditions (i.e., wherein detection d ′ = 0) frequently yield exclusively bidirectional effects—that is, effects driven by individual differences but with no main (i.e., mean) effects. This is exactly the case with our data: An ANOVA on our data produced no mean effects, while the regression analysis was strikingly productive.…”

“…The ODT may not only be the purest unconscious state our current methods can produce, but may also constitute a qualitatively different psychophysiological state susceptible to unconscious conflict activation. (It is also possible that similar findings might occur at other subliminal thresholds such as the subjective threshold at which d ′ > 0, but participants aver that they do not see the stimulus, hence subjective (Snodgrass et al, 2004a,b). This remains for future research to determine).…”

“…Snodgrass in a series of subsequent studies (Snodgrass et al, 1993a,b, 2004a,b) combined a signal detection theory approach with Shevrin's earlier psychophysical method, making it possible to go beyond the limitations of classical psychophysics and assess accuracy separately from bias. This made it possible to obtain an accurate measure of the objective detection threshold (ODT) free of criterion bias at which detection ( d ′) was not different from zero.…”

Suppressed semantic information accelerates analytic problem solving

“…However, it remained possible that suppression would not be complete on every trial; for instance, some participants might detect letter features on some trials. Debates on the unconscious perception can be found elsewhere in the literature (see Pratte & Rouder, 2009; Snodgrass, Bernat, & Shevrin, 2004; Yang & Blake, 2012). A total of 100 trials were presented: 40 problem word trials, 40 irrelevant word control trials, and 20 catch trials (all catch trials were excluded from the analysis).…”