Repetition priming without identification of the primes: evidence for a component process view of priming

The aim of the present study was to examine whether priming can occur due to recent perceptual processing of the same stimulus with minimal influence from conceptual process and also to investigate its underlying neural mechanisms using fMRI. Words were presented in mirror orientation in a word identification priming task. The presentation durations of the primes were titrated individually so that each participant could only identify approximately half of the primes, while the remainder disappeared before participants could identify the meaning of the word. A substantial behavioral priming effect was found when these unidentified primes were repeated later, suggesting that recent exposure to the perceptual processes without accessing the meaning is sufficient to prime later identical processes of the same repeated stimuli. Imaging data showed significant repetition suppression in several brain regions mediating perceptual, but not semantic or conceptual, processes. Together, our findings are consistent with the general predictions of transfer appropriate processing (TAP) and the component process view of priming, positing that priming is a function of more efficient cognitive processes that are repeated from study to test, and this increased efficiency is reflected in repetition suppression effects evident on fMRI.