Implicit Memory and Cognitive Aging
It is well documented that explicit (declarative, conscious) memory declines in normal aging. Studies have shown a progressive reduction in this form of memory with age, and healthy older adults (typically aged 65+ years) usually perform worse than younger adults (typically aged 18–30 years) on laboratory tests of explicit memory such as recall and recognition. In contrast, it is less clear whether implicit (procedural, unconscious) memory declines or remains stable in normal aging. Implicit memory is evident when previous experiences affect (e.g., facilitate) performance on tasks that do not require conscious recollection of those experiences. This can manifest in rehearsed motor skills, such as playing a musical instrument, but is typically indexed in the laboratory by the greater ease with which previously studied information is processed relative to non-studied information (e.g., repetition priming). While a vast amount of research has accumulated to suggest that implicit memory remains relatively stable over the adult lifespan, and is similar in samples of young and older adults, other studies have in contrast revealed that implicit memory is subject to age-related decline. Improving methods for determining whether implicit memory declines or remains stable with age is an important goal for future research, as the issue not only has significant implications for an aging society regarding interventions likely to ameliorate the effects of age-related explicit memory decline, but can also inform our theoretical understanding of human memory systems.