What Are the Functional Bases of Individual Differences in Memory Ability?

People differ markedly in memory ability, as in all other cognitive skills. Nevertheless, there are no satisfactory accounts of individual differences in the efficiency of functional processes underlying memory, possibly because cognitive psychologists have been more impressed by massive individual differences associated with extensive, domain specific practice (Ericcsen, Krampe, & Tesch-Rohmer, 1993) or invention and use of mnemonic techniques (Ericcsen & Chase, 1982; Ericcsen & Poison, 1988). Current models for how the efficiency of the functional processes underlying memory may vary between individuals polarize between identical hypotheses, remarkably without any cross-reference. One psychometric model proposes that all cognitive skills, including memory, load on a single factor of general intellectual ability such as Spearman’s (1927) “g” (for a recent discussion, see Gustafson, 1984). Interest in this somewhat dated view has been revived by the suggestion that “g” can be reified in terms of some particular performance parameter of the functional cognitive system. One suggestion has been information processing speed (Anderson, 1992; Bates & Eysenck, 1993; Brand & Deary, 1982; Eysenck, 1986; Hulme & Turnbull, 1983; Jensen, 1980; Nettelbeck, 1982; Smith & Stanley, 1983; Vernon, 1983, 1985; Vernon & Jensen, 1984). A more recent is “working memory capacity” (Carpenter, Just, & Shell, 1990; Kyllonen & Crystal, 1990). The evidence is modest, but ubiquitous correlations between performance on pencil-and-paper “intelligence tests” (IQ Test Scores, IQTS) and performance indices derived from simple laboratory tasks such as Choice Reaction Time (CRT) or tachistoscopic recognition thresholds (“Inspection Times,” ITs) and supposedly more direct indices of Central Nervous System (CNS) efficiency such as latencies of early, p¹⁰⁰ evoked potentials (Carly, 1994; Reed & Jensen, 1992), of thalamic events (Reed & Jensen, 1993), or complex patterns of potentials (Blinkhorn & Henderson, 1982; Hendricksen, 1982; Hendricksen & Hendricksen, 1980).