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A theory is proposed to account for some of the age-related differences reported in measures of Type A or fluid cognition. The central hypothesis in the theory is that increased age in adulthood is associated with a decrease in the speed with which many processing operations can be executed and that this reduction in speed leads to impairments in cognitive(More)
Recent research findings in the domain of transcription typing are reviewed in the context of a four-component heuristic model. The four components consist of an input phase in which to-be-typed text is grouped into familiar chunks, a parsing phase in which the chunks are decomposed into discrete characters, a translation phase in which characters are(More)
A meta-analysis was conducted on 91 studies to derive a correlation matrix for adult age, speed of processing, primary-working memory, episodic memory, reasoning, and spatial ability. Structural equation modeling with a single latent common cognitive factor showed that all cognitive measures shared substantial portions of age-related variance. A mediational(More)
Critical requirements for the hypothesis that executive functioning is a potential mediator of age-related effects on cognitive functioning are that variables assumed to reflect executive functioning represent a distinct construct and that age-related effects on other types of cognitive functioning are reduced when measures of executive functioning are(More)
Many variables have been assumed to reflect speed of processing, and most are strongly related to age in the period of adulthood. One of the primary theoretical questions with respect to aging and speed concerns the relative roles of specific and general age-related effects on particular speed variables. Distinguishing between specific (or unique) and(More)
It is widely believed that keeping mentally active will prevent age-related mental decline. The primary prediction of this mental-exercise hypothesis is that the rate of age-related decline in measures of cognitive functioning will be less pronounced for people who are more mentally active, or, equivalently, that the cognitive differences among people who(More)
The proposal that age-related differences in some measures of speed of performance may not be independent of the age-related differences in other measures of speed of performance has been associated with considerable controversy. Because converging evidence can often resolve this type of controversy, correlation-based procedures are proposed to distinguish(More)
Cross-sectional comparisons have consistently revealed that increased age is associated with lower levels of cognitive performance, even in the range from 18 to 60 years of age. However, the validity of cross-sectional comparisons of cognitive functioning in young and middle-aged adults has been questioned because of the discrepant age trends found in(More)
Results from three studies are reported in which adults between 18 and 84 years of age performed various versions of the Digit Symbol Substitution Test. The first study revealed that the age-related declines in digit-symbol performance were largely independent of both the amount of education the participants had received and their self-reported health(More)