Asking participants to rate their awareness of a briefly flashed, masked word during a semantic priming experiment changes the underlying cognitive processes. In two groups performing a lexical decision task, masked primes were shown for 20, 40, or 60 milliseconds. One group also rated prime visibility trial-by-trial using the Perceptual Awareness Scale; the other did not. Reaction-time and drift-diffusion modeling showed general priming effects on reaction time and drift rate only in the group without the rating task. In the rating group, residual priming effects appeared only on trials where participants reported seeing the prime, and affected non-decisional processing time. The concurrent rating task interferes with semantic priming, likely because it diverts attention to identifying the masked prime.
Whether emotional information can be processed without conscious awareness has been debated since psychology began. Many studies have used the masked sequential priming paradigm, where a briefly presented prime is followed by a mask to prevent conscious perception, and participants categorize target stimuli by valence. Faster responses when prime and target share the same valence suggest non-conscious processing. This review examines three questions: the methods used to establish non-conscious processing, evidence for non-conscious extraction of evaluative information, and evidence for non-conscious processing beyond simple positive/negative discrimination, such as emotion-specific features. The review highlights current debates and future directions for the field.