Knowledge, expertise, and aging.
Not surprisingly, older adults have acquired more domain-specific knowledge than younger adults. In one study, Ackerman (2000) administered measures of cognitive ability alongside measures of knowledge in 18 domains (including art, music, world literature, biology, technology, and law) to a sample of 228 educated adults between the ages of 21 and 62. As expected, middle-aged adults displayed much higher domain-specific knowledge compared with younger adults.
The effect of age on expertise also depends on the nature of the accumulated knowledge (procedural or declarative). In general, success in domains that rely heavily on declarative knowledge tends to be correlated with cognitive ability (Ackerman, 2011; Schipolowski, Wilhelm, & Schroeders, 2014). There are between-domain differences, however. Fluid or nonverbal intelligence is more strongly related to knowledge in mathematics and the sciences, whereas verbal or crystallized intelligence is more strongly related to knowledge in the humanities (Ackerman, 2011; Park, Lubinski, & Benbow, 2007). In contrast, domains in which performance depends more on procedural knowledge (e.g., sports and dance) show diminished associations with cognitive ability as expertise increases, perhaps because of their reliance on perceptual-motor functions (Ackerman, 2011).
From a life span perspective, general knowledge, domain-specific knowledge, and procedural skills, once acquired, tend to be preserved over most of the life span (Ackerman, 2011), and the acquisition of knowledge has been shown to help compensate for the decline of cognitive ability in a wide variety of domains, from football to music to chess to science (Ericsson, 2013). In addition, the benefits of knowledge are cumulative: Early success provides advantages that initiate a virtuous cycle (Merton, 1968; Petersen, Jung, Yang, & Stanley, 2011), with early knowledge stimulating the discovery and use of more knowledge, so multiplying the chances that creative ideas will emerge.
While many cognitive abilities decline as we age, knowledge and expertise increase, and these factors play a major, necessary role in creativity. Increased knowledge may help compensate for decreased mental speed, decreased short-term memory, poorer fluid reasoning, and less originality as we age.