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Abstract:
Previous research has consistently demonstrated age
differences in executive abilities in the absence of differences in
other cognitive abilities (Daigneault & Braun, 1993). Although,
these differences are consistent with frontal lobe neuropathology
associated with the healthy aging, it remains possible that the
differences are related to age declines in psychomotor speed
(Salthouse, 1996). The relationship between age and executive
ability was examined in 40 healthy older and 46 young adults in
order to determine whether the relationship between age and
executive ability is unique or an artifact of psychomotor slowing.
Participants were administered tasks of set formation and set
shifting ability in both verbal and nonverbal domains. Each
executive task was paired to a psychomotor speed task with parallel
demands barring an executive component. Hierarchical regression
analyses were used to examine the unique contribution of age to
executive task performance after adequately controlling for
psychomotor speed. Psychomotor speed was entered in the first step
of the analyses, and age was entered in the second step. Results
revealed that increased age was associated with poorer executive
performance (p < .01). Further, after controlling for
psychomotor speed, age uniquely contributed to executive task
performance (p < .01). These results suggest that although
psychomotor speed factors may significantly attenuate the relation
between age and executive abilities, once speed-related factors are
adequately controlled, a unique relationship between age and
executive abilities remains.
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