Executive functions and intelligence are related, but not
interchangeable. That answer sounds simple until we ask what executive
functions means. Inhibition, shifting between rules, updating
working memory and maintaining goal-relevant information are often
grouped under the same label, yet research does not show that all of
them relate to intelligence in the same way. The relationship is therefore not:
more executive function = more intelligence.
It is a pattern of unequal overlap among partly distinct
cognitive processes.
Why should they overlap at
all?
Consider a novel reasoning problem. Finding the solution may require discovering a relationship, but
successful performance also depends on keeping the task goal accessible,
preserving intermediate results, abandoning an interpretation that has
stopped working and preventing irrelevant information from taking
control of the search. Those control demands create an obvious point of contact between
reasoning and executive function. The overlap is especially plausible for fluid intelligence: the
capacity to solve unfamiliar problems without relying entirely on
previously learned answers. Novel problems place a premium on
maintaining and reorganizing information while controlling
attention. But plausibility is not evidence that executive function and
intelligence are the same construct. To test that claim, researchers
need several tasks and models that can separate what the tasks share
from what is specific to each one.
Executive function is not
one ability
A foundational latent-variable study by Miyake and colleagues showed
that three commonly studied executive functions—updating, shifting and
inhibition—were correlated but separable. This became known as the
unity-and-diversity view of executive function. Later work has complicated the exact factor structure. A systematic
review and re-analysis of 46 samples found that the best-fitting
organization varies across age groups and studies rather than reducing
cleanly to one universal three-factor model. That uncertainty matters here. If executive function is not one homogeneous ability, asking for
the correlation between executive function and intelligence can
conceal more than it reveals. The more informative question is which executive processes show the
strongest relationship.
Updating has often
shown the clearest link
In an influential 2006 study, Friedman and colleagues compared
intelligence with inhibition, shifting and updating—the process of
replacing no-longer-relevant information in working memory with
information that has become relevant. Updating was strongly related to the intelligence measures. Once
overlap among the executive functions was modeled, inhibition and
shifting showed much smaller, nonsignificant relationships in that
sample. That result is important, but it should not be turned into a
universal ranking. Other studies have produced somewhat different patterns. For example,
work decomposing fluid-intelligence performance has found relationships
involving inhibition as well as updating, depending on which component
of the intelligence task was modeled. The defensible conclusion is therefore not that “updating is
intelligence.” It is that different executive functions relate
differently to intelligence, and updating or closely related
working-memory control processes have often shown particularly
substantial overlap.
Working memory
makes the boundary even less tidy
Working memory sits near the center of this literature because it
involves keeping information accessible while cognition continues. Meta-analytic and latent-variable research shows a substantial
relationship between working-memory capacity and intelligence,
especially fluid reasoning. Estimates vary with the tasks and methods
used. Ackerman and colleagues’ meta-analysis of 86 samples concluded that
working memory and general intelligence were clearly not identical. In
the same debate, Kane and colleagues reanalyzed latent-variable studies
and estimated a much stronger median relationship between working-memory
capacity and fluid reasoning. The disagreement over magnitude is itself instructive. The relationship depends partly on what researchers count as working
memory, which intelligence measures they use, and whether observed tasks
or latent constructs are compared. Strong overlap does not settle construct identity.
Executive
attention offers a mechanism, not a settled verdict
One influential account emphasizes executive
attention: the ability to keep goal-relevant information active
and control interference from information that is no longer useful. Engle has argued that this form of attentional control helps explain
why working-memory measures predict fluid intelligence. In his later
formulation, working-memory tasks emphasize maintaining information,
whereas fluid-intelligence problems can depend heavily on disengaging
from representations that have become unhelpful. That is an explanatory proposal about the mechanism behind the
correlation. It is not the only possible explanation, and factor-analytic overlap
by itself cannot establish that executive attention causes
intelligence. The distinction is central to HIW’s treatment of cognitive
relationships: a statistical association tells us what tends to vary
together. A theory is still needed to explain why.
Measurement
makes the relationship harder to isolate
Executive-function tasks have a well-known task-impurity
problem. A task intended to measure inhibition also requires perception,
comprehension, response selection and usually some form of memory. A
shifting task requires learning the rules being shifted between. An
updating task requires information to be encoded and maintained. Intelligence tests are mixtures too. A reasoning item can recruit
visual processing, working memory, learned strategies and attention
alongside the relational reasoning researchers are interested in. A correlation between two tasks can therefore reflect their target
constructs, shared supporting processes, or both. Latent-variable methods reduce some of this problem by estimating
what several tasks have in common. They do not make measurement
pure.
Are executive
functions part of intelligence?
That depends partly on the level of description. Psychometric models of intelligence already include broad and narrow
cognitive abilities that draw on memory, speed and other processes.
Executive-function research approaches cognition from a somewhat
different tradition, asking how thought and action are controlled in the
service of goals. The two traditions overlap without mapping perfectly onto one
another. Friedman and Miyake’s review of individual differences explicitly
concluded that commonly studied executive functions are not the
same as general intelligence or g, even though they
are related. This leaves a useful asymmetry. Complex intelligent behavior often requires executive control. But
executive control is not sufficient to explain the full structure of
intelligence. Knowledge, reasoning, processing speed, memory, perceptual
abilities and other forms of cognitive variation remain part of the
picture.
What should we conclude?
Executive functions and intelligence overlap because intelligent
performance frequently requires the control of thought: keeping goals
active, managing interference, updating relevant information and
changing what cognition is doing when circumstances demand it. But the overlap is selective. Updating and working-memory-related control have often shown
particularly strong relationships with fluid intelligence. Inhibition
and shifting show more variable associations. The precise pattern
depends on how both executive functions and intelligence are
measured. So the evidence supports neither extreme. Executive functions are not independent of intelligence. They are also not simply intelligence under another name. The scientifically interesting territory lies between those claims:
which control processes contribute to intelligent performance,
how strongly, and why?
References
- Ackerman, P. L., Beier, M. E., & Boyle, M. O. (2005). Working
memory and intelligence: The same or different constructs?
Psychological Bulletin, 131(1), 30–60.
DOI - Engle, R. W. (2018). Working memory and executive attention: A
revisit. Perspectives on Psychological Science, 13(2), 190–193.
DOI - Friedman, N. P., & Miyake, A. (2017). Unity and diversity of
executive functions: Individual differences as a window on cognitive
structure. Cortex, 86, 186–204.
DOI - Friedman, N. P., Miyake, A., Corley, R. P., Young, S. E., DeFries,
J. C., & Hewitt, J. K. (2006). Not all executive functions are
related to intelligence. Psychological Science, 17(2), 172–179.
DOI - Kane, M. J., Hambrick, D. Z., & Conway, A. R. A. (2005). Working
memory capacity and fluid intelligence are strongly related constructs:
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DOI - Karr, J. E., Areshenkoff, C. N., Rast, P., Hofer, S. M., Iverson, G.
L., & Garcia-Barrera, M. A. (2018). The unity and diversity of
executive functions: A systematic review and re-analysis of latent
variable studies. Psychological Bulletin, 144(11), 1147–1185.
DOI - Miyake, A., Friedman, N. P., Emerson, M. J., Witzki, A. H.,
Howerter, A., & Wager, T. D. (2000). The unity and diversity of
executive functions and their contributions to complex “frontal lobe”
tasks: A latent variable analysis. Cognitive Psychology, 41(1),
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