Abstract
Recent research has been shedding light on the interplay between human working memory capabilities and their performance across various cognitive tasks. This connection suggests that variations in these cognitive processes might be underlying factors for individual differences in intelligence. This article offers a concise review of relevant data supporting this notion. Furthermore, it highlights a developing body of work focused on genetically diverse mice, showcasing an analog to general intelligence akin to human intelligence (g). Similar to humans, this animal equivalent of g corresponds with differences in both the storage and processing aspects of the working memory system. The unique advantage of studying animals allows for the manipulation of specific working memory components, like selective attention, enabling observation of causal relationships with general cognitive abilities. In parallel with this animal research, human imaging studies are briefly discussed, indicating common brain structures, such as the prefrontal cortex, that influence selective attention and performance in intelligence assessments. This collective evidence points to a shared evolutionary foundation for processes linked to intelligence, offering insights into enhancing these abilities in various species, young and old.
Introduction
Over the past half-century, the concept of working memory has evolved significantly, from its original introduction by Miller in 1956. While differing slightly from modern interpretations, Baddeley and Hitch’s 1974 depiction aligns closely with contemporary understanding. They explored subjects’ performance under high and low interference conditions in tasks related to list learning, retrieval, and comprehension. This led to the proposal of a limited resource working memory system with storage and processing components that trade-off depending on task complexity. Working memory has since been acknowledged as a dynamic system that simultaneously maintains information and facilitates complex cognitive tasks.
Working memory, with its sub-components, has been postulated as a potential latent factor contributing to general cognitive abilities, or intelligence. This article reviews evidence from the human domain supporting the idea that specific working memory components correlate with performance in various cognitive ability tests. Additionally, it delves into recent findings concerning genetically heterogeneous mice that display traits analogous to human intelligence. This approach explores aggregate performance across multiple learning and attention tasks in animals, similar in some aspects to characterizing individual differences in human intelligence. The unique opportunity presented by animal research allows manipulation of working memory components, like selective attention, revealing causal relationships with overall cognitive abilities. This research runs parallel with human studies using brain imaging, suggesting common brain structures mediating selective attention and intelligence test performance. In essence, this evidence signifies an evolutionary continuity of processes underpinning intelligence, offering a framework for enhancing cognitive abilities across species and ages.
Working Memory and Intelligence in Humans
Underwood’s 1975 assertion emphasized testing individual differences to evaluate psychological theories. If Mechanism “A” underlies Process “B,” differences in Mechanism “A” should predict corresponding variations in Process “B.” This approach has contributed to the view that processing components of working memory may underlie intelligence differences.
General Cognitive Abilities in Genetically Heterogeneous Mice
Addressing complexities in human research, our laboratory devised a regimen to assess cognitive abilities in genetically diverse mice. This entailed testing mice in a battery of five learning tasks, each imposing unique sensory, motor, and information processing demands. The findings from this study were rooted in fundamental tasks.
Neuroanatomical and Neurophysiological Substrates of General Cognitive Abilities
A similar approach has extended to studying the co-variation of brain activity and intelligence, working memory, and selective attention in humans and animals. While correlational in nature, this research provides insight into the interplay between cognitive processes and neural activity.
Summary
The interconnectedness between working memory and intelligence, evident in human and animal research, suggests a shared constraint. Evidence points to limitations in both storage and processing components (e.g., selective attention) of the working memory system as shaping higher cognitive functions. These capacities interact to influence specific task completion.
Acknowledgments
Support for this work was provided by grants from the National Institute of Aging (R01AG029289 and AG022698) and the Busch Foundation.