Long-term priming has been one of the most thoroughly studied phenomena in cognitive
psychology during the past 20 years. Excitement in this area was initially inspired by the
observation that densely amnesic patients show robust (sometimes normal) memory for
pictures and words when items are presented in a fragmented format at test and memory
is tested indirectly. This occurs despite poor (sometimes chance) performance on recall and
recognition tasks (e.g.,Warrington and Weiskrantz, 1974). These findings led to important
claims regarding the nature of amnesia, and more generally, opened up research to the
experimental study of ‘unconscious’ or ‘implicit’ memories. Later work showed that this
memory—now called long-term priming—can be studied in people with normally functioning
memories (e.g., Jacoby and Dallas, 1981; Tulving et al., 1982), making unconscious
memory still more accessible to empirical study.
Within this tradition, a primary question has been how priming (and more generally
implicit memory) relates to recall and recognition. One of the central debates from this
perspective is whether priming and episodic memory should be explained within a single
memory system or through qualitatively different memory systems. An underlying
assumption in this perspective, then, is that priming is mediated by a system whose
main function is memory—although the specific function of this system is rarely
described.