The relationship between working memory capacity and executive functioning: evidence for a common executive attention construct

Abstract

Attentional control has been conceptualized as executive functioning by neuropsychologists and as working memory capacity by experimental psychologists. We examined the relationship between these constructs using a factor analytic approach in an adult life span sample. Several tests of working memory capacity and executive function were administered to more than 200 subjects between 18 and 90 years of age, along with tests of processing speed and episodic memory. The correlation between working memory capacity and executive functioning constructs was very strong (r = .97), but correlations between these constructs and processing speed were considerably weaker (rs approximately .79). Controlling for working memory capacity and executive function eliminated age effects on episodic memory, and working memory capacity and executive function accounted for variance in episodic memory beyond that accounted for by processing speed. We conclude that tests of working memory capacity and executive function share a common underlying executive attention component that is strongly predictive of higher level cognition.

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Figures

Figure 1

Age-related differences in performance on each factor score for each cognitive domain. There were significant age-related declines in performance on all factor scores, except vocabulary, which showed an age-related increase.

Figure 2

Model A: Factor analysis examining the relation between the working memory capacity, executive functioning, and processing speed constructs. Model B: Factor analysis with a single executive attention construct defined by the working memory capacity and executive function measures. Circles represent the latent variables, boxes represent each observed variable. RS = Reading Span; LRS = Letter Rotation Span; MS = Match Span; CS = Computation Span; BDS = Backward Digit Span; MA = Mental Arithmetic; MC = Mental Control; FAS = Letter Fluency; WCST = Wisconsin Card Sorting Test; RAPM = Raven's Advanced Progressive Matrices; SR = Space Relations; LS = Letter Sets

Figure 3

Structural equation models examining the relation between age and episodic memory with either working memory capacity (A1), executive functioning (A2), or executive attention (A3) as the mediator. Solid lines represent significant correlations (p < .01), dotted lines represent non-significant correlations.

Figure 4

Structural equation models examining the relation between age and episodic memory, with processing speed mediating the relationship between working memory capacity (B1), executive functioning (B2), or executive attention (B3), and episodic memory. Solid lines represent significant correlations (p < .01), dotted lines represent non-significant correlations.