In: Nursing
what is memory? How is memory affected across the life span?
Memory is the faculty of the brain by which data or information
is encoded, stored, and retrieved when needed. It is the retention
of information over time for the purpose of influencing future
action. Knowledge and access to knowledge is well preserved in
adulthood. It declines rather late in life, more precociously with
pathologies of memory than with normal aging. Several factors that
influence memory development such as changes in the brain regions
envisioned by Lindenberger and collegues in their life span theory
of memory development.Although space precludes a detailed treatment
of other influences.We treat briefly two other aspects: a
psychological account of memory development based on the concept of
cognitive resources, and the infl uence of pathological memory
change in later life.
Cognitive Resources
By some accounts, basic processing mechanisms can be viewed as
resources that can be flexibly allocated in service of achieving
cognitive goals. Here, we selectively discuss two basic cognitive
resources (i.e., WM and processing speed) that received
considerable attention in both fi elds of cognitive development and
aging. WM is a critical resource for encoding information into
episodic memory, as well as other higher-order forms of cognition
such as inductive reasoning (e.g., Kyllonen & Christal, 1990;
Hultsch et al., 1998; Salthouse, 1991). Developmental changes in WM
have been cited as a major cause ofhigher cognitive development in
children (Gathercole, 1998) and as a cause of age-related decline
in episodic memory (Salthouse & Babcock, 1991; Stine-Morrow et
al., 2006). WM changes are highly associated with episodic memory
changes in adulthood (Hertzog et al., 2003; Hultsch et al., 1998).
Theories of cognitive development emphasizing the role of
processing speed have also been formulated for both ends of the
life span (Birren, 1965; Kail & Salthouse, 1994; Salthouse,
1996). For instance, Kail and Park (1994) showed that there is a
relationship between processing speed and memory span mediated by
articulation rate. In aging, cross-sectional studies have found
that between 44 and 80% of cross-sectional age variance in memory
task was associated with psychometric tests of perceptual speed
(Salthouse, 1996; Verhaeghen & Salthouse, 1997). However,
reduced resource explanations of aging have been challenged on
several grounds, including (1) the measurement properties and
cognitive constituents of tests of processing speed (e.g., Hertzog,
1989; Lustig, Hasher, & Tonev, 2006);
(2) whether one of these information-processing constructs is more
basic than the variables they are used to predict (Deary, 2001;
Light, 1991); and (3) methodological problems with regression-based
estimates of resource-determined age-related variance using
cross-sectional data (Hofer, Flaherty, & Hoffman, 2006;
Lindenberger & Pötter, 1998). For example, longitudinal data
typically show smaller effects of changes in speed and WM on
changes in episodic memory performance (Hertzog et al., 2003;
Hultsch et al., 1998).