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.

Fig. 1

Free-association priming, cued recall, and recognition memory in Experiment 1. Results are shown separately for the control group (CON, n=6), amnesic patients with large medial temporal lobe lesions (MTL, n=2), and amnesic patients with lesions thought to be limited to the hippocampal region (H, n=3). Participants were given each of the three tests four different times, using similar materials. The measure of priming (a) is the difference between the percentage of studied and unstudied words produced at test in response to an associate of each word. The measure of cued recall (b) is the percentage of studied words recalled in response to an associate of each studied word. The measure of recognition memory (c) is the percentage of correct responses (hits plus correct rejections) for yes/no recognition. The data points for the MTL and H groups show the scores of individual patients averaged across the four separate tests. The dashed line in (c) indicates chance performance. Brackets show standard errors of the mean.

Fig. 2

Category-verification priming and recognition memory in Experiment 2. Results are shown separately for the control group (CON, n=12), amnesic patients with large medial temporal lobe lesions (MTL, n=2), and amnesic patients with lesions thought to be limited to the hippocampal region (H, n=3). Participants were given each of the two tests four different times, using similar materials. The measure of priming in (a) is response time for studied words minus response time for unstudied words. Panel (b) shows the priming score from (a) divided by the response time for unstudied words (baseline response time). The measure of recognition memory (c) is the percentage correct responses (hits plus correct rejections) for yes/no recognition. The data points for the MTL and H groups show the scores of individual patients averaged across the four separate tests. The dashed line in (c) indicates chance performance. Brackets show standard errors of the mean.