This special edition commemorates the roughly 50 years of theoretical work on cognitive aging. As an Introduction to this issue, we first briefly review cognitive aging efforts prior to the mid-1960s, then describe the mid-1960s as a pivotal point for cognitive aging theory, and finally comment on how the field has evolved since then.
Cognitive Aging Research Prior to the Mid-1960s
Observations of cognitive aging date back millennia. Take, for instance, the sixth century BC poet Solon who, in writing about life’s hebdomads, or periods of 7 years, “… in the ninth, though he’s still capable, his tongue and expertise have lost some of their force” (Baars, 2012). Empirical proof of cognitive aging appeared in the 1930s, when Miles evaluated the perceptual, motor, and cognitive abilities of 1600 people aged 6 to 95 years old, and reported declines after age 30 in these skills, including learning ability (e.g., Miles, 1933). Age-related slowing emerged as a salient feature in the 1930s; the fact that most intelligence tests were speeded led Lorge (1940) to correct intelligence test data for speed of processing, finding that intelligence did not, in fact, decline with age. Lorge’s discovery of the relationship between speed and intellectual capacity reminds us of Salthouse’s later and more encompassing theory that agerelated changes in speed underlie changes in a number of cognitive domains (e.g., Salthouse, 1996).
– The Gerontological Society of America