Distinguishing conscious from unconscious perceptual processes.

Abstract

A widely accepted assumption is that the boundary between conscious and unconscious perceptual processes is most appropriately defined in terms of a threshold for discriminative responding. Although many studies have been based on this assumption, no generally accepted conclusions have emerged concerning whether or not unconsciously perceived visual stimuli lead to semantic analysis. In the present studies, the boundary between conscious and unconscious perceptual processes was equated with a subjectively-defined threshold based on claimed awareness rather than an objective threshold based on discriminative responding. The results of two experiments involving a Stroop-priming task indicated that masked colour words presented above and below a subjective threshold were effective primes for the subsequent naming of colour patches. More importantly, the results also indicated different effects; variations in the proportion of trials on which primes and targets were congruent led to the adoption of a predictive strategy when the primes were presented above the subjective threshold, but no evidence for the adoption of a predictive strategy was found when the primes were presented below the subjective threshold. It is concluded that a subjectively-defined awareness threshold captures the phenomenological distinction between conscious and unconscious experiences and provides a basis for establishing the qualitative differences that distingish conscious from unconscious perceptual processes.