A dissociation between conscious perception and stimulus processing: the effects of prior exposure to high-visibility stimuli

摘要

Recent research has shown that discrimination of a barely visible stimulus is greatly enhanced following exposure to a clear version of this stimulus (Ahissar & Hochstein, 2004; Lin & Murray, 2014). However, whether such enhancement affects only conscious perception of the critical stimulus or also the extent to which it is processed and can indirectly affect behavior has not been addressed. Here, we presented a small prime arrow followed by a larger target arrow that served as backward pattern mask. Observers responded to the direction of the target. We manipulated the stimulus-onset asynchrony (SOA) between the prime and mask either by randomly mixing them or by presenting them in separate blocks of increasing durations (i.e., decreasing mask effectiveness). Conscious perception of the prime was assessed either using the 4-level Perceptual Awareness Scale (subjective measure) or as forced-choice discrimination performance (objective measure). Processing of the prime was measured as the effect on performance of the compatibility between the prime and target arrows. The results show that for short exposure durations, both subjective and objective awareness of the prime were dramatically lower in the blocked than in the mixed condition. However, compatibility effects were unaffected by the blocked vs. mixed SOA manipulation. Thus, prior exposure to high-visibility primes affected conscious perception but not processing of briefly presented primes. The methodological implications of these findings for the study of unconscious processing are discussed.