Timeline of the Development of the Concept of Working Memory

This is a follow up to my last article, Executive Functions and Working Memory. In this one we are going over the historical timeline of the significant studies and theories in understanding of how memory seems to function.

1890 - William James' "The Principles of Psychology"

William James distinguished between primary memory (immediate content of consciousness) and secondary memory (long-term storage). He emphasized the active nature of memory processes, which laid the foundation for future theories of working memory. His ideas influenced the understanding of memory, especially short-term or working memory (James, 1890).

1956 - George A. Miller's "The Magical Number Seven, Plus or Minus Two"

Miller proposed that short-term memory has a limited capacity of about seven items (+/- 2), now known as Miller’s Law. This research was pivotal in understanding the constraints of short-term memory, influencing later working memory models. (Miller, 1956).

1968 - Atkinson and Shiffrin's Multi-Store Model

This work introduced the distinction between sensory memory, short-term memory (STM), and long-term memory (LTM), conceptualizing STM as a distinct stage in memory processing. Atkinson and Shiffrin's model provided a framework that integrated short-term and long-term memory as separate components, influencing future research in working memory. (Atkinson, R. C., & Shiffrin, R. M., 1968).

1974 - Baddeley and Hitch's Model of Working Memory

Alan Baddeley and Graham Hitch introduced the multi-component model of working memory, which included the phonological loop, visuospatial sketchpad, and central executive. This model shifted focus from memory as mere storage to active processing, significantly shaping modern cognitive psychology (Baddeley AD, Hitch G., 1974).

1981 - Baddeley's Refinement of Working Memory

Baddeley further developed the concept of working memory, elaborating on its role in complex cognitive tasks such as reasoning and comprehension. This revision highlighted the differentiation between working memory and long-term memory, emphasizing its importance in cognitive processes (Baddeley, A., 1981).

1984 - Endel Tulving's Research on Memory Systems

Tulving's work on episodic memory provided insights into how memory systems, including working memory, interact and function. His distinction between episodic and semantic memory enriched the understanding of how working memory relates to long-term memory systems (Tulving, E., 1984).

1997 - Luck and Vogel's Research on Visual Working Memory

Demonstrated that visual working memory retains integrated objects, rather than individual features, suggesting a more complex structure. Refined the understanding of visual working memory’s capacity, emphasizing its ability to handle complex information (Luck, S. J., & Vogel, E. K., 1997).

2000 - Baddeley's Addition of the Episodic Buffer

Alan Baddeley introduced the episodic buffer as a component of working memory that integrates information across domains and links to long-term memory. This addition addressed how different types of information are bound together in working memory, making the model more comprehensive (Baddeley, A., 2000).

2001 - Cowan's "The Magical Number 4"

Nelson Cowan refined Miller's work, suggesting that the capacity of working memory is closer to four items rather than seven. This research provided a more accurate understanding of working memory capacity, influencing future studies (Cowan, N., 2001).

2003 - Baddeley's Retrospective on Working Memory

In this review, Baddeley reflected on the evolution of working memory research, discussing its implications for neuroscience and cognitive psychology. This work highlighted the advancements in working memory research and set the stage for future directions (Baddeley, A., 2003).

2005 - Cowen – Embedded Processes Model

Nelson Cowan proposed that working memory is not a separate system but is part of long-term memory, consisting of activated representations held in the focus of attention. This theory challenged the idea of a separate working memory system, emphasizing attentional control within long-term memory (Cowan, 2005).

2014 - Ji et al.'s Changing Concepts of Working Memory

This review emphasized that working memory should be viewed as a limited resource that can be flexibly allocated among items, focusing on quality over quantity. This view reshaped the understanding of how working memory operates under capacity limitations (Ji et al., 2014).

2014 - Advances in Neuroscience and Working Memory

Neuroimaging studies explored the neural correlates of working memory, focusing on areas such as the prefrontal cortex. These studies deepened our understanding of the brain mechanisms involved in working memory (Hackman et al., 2014).

Summary of Key Contributions

References

Atkinson, R. C., & Shiffrin, R. M. (1968). Human memory: A proposed system and its control processes. In Psychology of learning and motivation (Vol. 2, pp. 89-195). Academic press. https://doi.org/10.1016/S0079-7421(08)60422-3

Baddeley AD, Hitch G. (1974) Working memory. In: Bower GH, editor. The psychology of learning and motivation: Advances in research and theory. Vol. 8. New York: Academic Press; 1974. pp. 47–89. https://doi.org/10.1016/s0079-7421(08)60452-1.

Baddeley, A. (1981). The concept of working memory: A view of its current state and probable future development. Cognition, 10(1-3), 17-23. https://doi.org/10.1016/0010-0277(81)90020-2

Baddeley, A.D. (2000). The episodic buffer: a new component of working memory? Trends in Cognitive Sciences, 4, 417-423. https://doi.org/10.1016/S1364-6613(00)01538-2

Baddeley, A. (2003). Working memory: Looking back and looking forward. Nature Reviews Neuroscience, 4(10), 829-839. https://doi.org/10.1038/nrn1201

Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24(1), 87-114. https://doi.org/10.1017/S0140525X01003922

Cowan, N. (2005). Working Memory Capacity (1st ed.). Psychology Press. https://doi.org/10.4324/9780203342398

Hackman, D. A., Betancourt, L. M., Gallop, R., Romer, D., Brodsky, N. L., Hurt, H., & Farah, M. J. (2014). Mapping the trajectory of socioeconomic disparity in working memory: Parental and neighborhood factors. Child Development, 85(4), 1433-1445. https://doi.org/10.1111/cdev.12242

James, W. (1877). The principles of psychology. The Journal of Nervous and Mental Disease, 4(4), 305-309. https://doi.org/10.1097/00005053-187704000-00009

Luck, S. J., & Vogel, E. K. (1997). The capacity of visual working memory for features and conjunctions. Nature, 390(6657), 279-281. https://doi.org/10.1038/36846

Ma, W., Husain, M., & Bays, P. (2014). Changing concepts of working memory. Nature Neuroscience, 17, 347-356. https://doi.org/10.1038/nn.3655

Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological review, 63(2), 81. https://doi.org/10.1037/h0043158

Tulving, E. (1984). Précis of Elements of episodic memory. Behavioral and Brain Sciences, 7(2), 223-238. https://doi.org/10.1017/S0140525X0004440X