Repetition Priming

Repetition priming is the finding that a person processes a stimulus more quickly or more accurately when they have encountered that same, or a very closely related, stimulus previously, even when they have no conscious memory of that earlier encounter at all. It is distinguished from semantic priming, documented elsewhere in this section, by the basis of the improvement: semantic priming depends on a meaningful relationship between two different but related items, such as doctor and nurse, whereas repetition priming depends specifically on prior direct exposure to the identical or near-identical stimulus itself, such as reading the same word twice within an experimental session. Repetition priming is one of the most extensively studied forms of implicit memory, the broad category of memory effects that influence behavior without requiring, or sometimes even permitting, conscious recollection of the specific past experience responsible for them, and it has been documented in populations with severe amnesia who show clear priming benefits for previously encountered material despite having no explicit memory of ever having seen it before. Because the effect can persist across substantial delays and appears to rely on different underlying brain systems than those responsible for conscious, effortful recollection, repetition priming has played an important role in cognitive neuroscience research distinguishing separate implicit and explicit memory systems within the brain.