Intact Conceptual Priming in the Absence of Declarative Memory

Abstract

Priming is an unconscious (nondeclarative) form of memory whereby identification or production of an item is improved by an earlier encounter. It has been proposed that declarative memory and priming might be related-for example, that conceptual priming results in more fluent processing, thereby providing a basis for familiarity judgments. In two experiments, we assessed conceptual priming and recognition memory across a 5-min interval in 5 memory-impaired patients. All patients exhibited fully intact priming in tests of both free association (study tent; at test, provide an association to canvas) and category verification (study lemon; at test, decide: Is lemon a type of fruit?). Yet the 2 most severely amnesic patients performed at chance on matched tests of recognition memory. These findings count against the notion that conceptual priming provides feelings of familiarity that can support accurate recognition judgments. We suggest that priming is inaccessible to conscious awareness and does not influence declarative memory.Declarative memory supports the capacity for conscious recollection of facts and events and can be contrasted with a collection of non-declarative memory abilities, including habits and skills, simple forms of conditioning, and other ways by which experience can change how people interact with the world (Milner, Squire, & Kandel, 1998). One well-studied example of nondeclarative memory is the phenomenon of priming, whereby an encounter with an item improves the ability to identify or produce the same item (perceptual priming) or a related item (conceptual or semantic priming;Schacter & Buckner, 1998;Tulving & Schacter, 1990).There has been extended exploration of the possibility that priming and declarative memory might be related in some way. For example, it has been proposed that recognition memory may be supported in part by the fluency with which items are processed. That is, priming may result in improved, more fluent processing that provides a basis for judging items as familiar (Jacoby & Dallas, 1981;Verfaellie & Keane, 2002;Yonelinas, Regehr, & Jacoby, 1995). This idea has been addressed most thoroughly in the case of perceptual (or repetition) priming, which is demonstrated in tasks such as word identification and word-stem completion. In perceptual priming, a specific perceptual operation is enhanced, and the priming effect does not depend on carrying out semantic or elaborative encoding at the time of study. Three studies are particularly relevant to this issue. First, in undergraduate volunteers, familiarity judgments and repetition priming (word identification or word-stem completion) were affected differently by manipulations of perceptual and conceptual processing. Thus, recognition and repetition priming were sharply dissociable (Wagner, Gabrieli, & Verfaellie, 1997). Second, the severely amnesic patient E.P. was fully intact at perceptual priming, despite performing at chance on matched tests of recognition memory (Hamann & Squire, 1997). Third, in five additional e...

On the contribution of perceptual fluency and priming to recognition memory

“…and G.P. exhibited fully intact conceptual priming during free-association tests and category verification tests but performed at chance on recognition memory tests involving the same words as those used to demonstrate priming (Levy et al, 2004). These findings suggest that conceptual fluency is not a useful source of information about familiarity.…”

“…A difficulty with this view is that patients with large medial temporal lobe lesions and profound memory impairment can perform at chance on conventional recognition memory tests, despite exhibiting intact perceptual and conceptual priming (Hamann & Squire, 1997;Levy, Stark, & Squire, 2004;Stark & Squire, 2000). There appear to be two ways to understand these findings.…”

Neural correlates of conceptual implicit memory and their contamination of putative neural correlates of explicit memory

“…Effective connectivity analyses might also provide relevant evidence. However, compelling dissociations between conceptual priming and explicit memory have been provided by neuropsychological studies in amnesic patients (Graf et al 1985;Vaidya et al 1995;Keane et al 1997;Levy et al 2004). Research that might verify such dissociations in healthy individuals by directly examining putative functional relationships can now be pursued by making use of neural correlates of memory as characterized in the present study.…”

Investigating the functional interaction between semantic and episodic memory: Convergent behavioral and electrophysiological evidence for the role of familiarity

“…Moreover, evidence from normal (Wolk et al, 2004) and amnesic (Olichney et al, 2000) participants suggests that conceptual priming modulates the N400 component, separate from the mid-frontal ERP old/new effect. There are also clear examples of dissociations between conceptual priming and episodic memory retrieval using other neuroimaging methods (Donaldson et al, 2001) and neuropsychological data (Levy et al, 2004). We therefore favor the view that, at least for verbal material, the conscious experience of familiarity and the unconscious activation associated with conceptual priming are both functionally and neurally distinct.…”