Recognition and lexical decision without detection: unconscious perception?

Stimulus detection and concurrent measures of stimulus recognition were compared to establish whether perception occurs in the absence of detection. The target stimuli were familiar words (Experiments 1 and 2), nonwords (Experiment 3), or both words and nonwords (Experiment 4). On each trial, either a stimulus or a blank field was presented. Ss first decided whether a stimulus had been presented and then made either a forced-choice recognition decision (Experiments 1, 2, and 3) or a lexical decision (Experiment 4). Both words and nonwords were recognized and discriminated following correct detections (i.e., hits). However, in the absence of stimulus detection (i.e., misses), only words were recognized or discriminated. These qualitatively different patterns of results following hits and misses for words and nonwords suggest that stimulus detection may provide an adequate measure of conscious awareness.