Key ideas
Core concepts
- What feels like multitasking is rapid task switching, not simultaneous processing.
- Each switch costs working memory: deactivating one context, activating another, then switching back delays deep focus and fatigues cognitive resources. Multitaskers feel more productive whilst achieving less and making more errors (Rosen, 2008).
Multitasking is the attempt to perform multiple tasks at once. In practice it involves rapid task switching, which increases Cognitive Load and reduces performance through the Redundancy Effect.
Connected to
Cognitive Load Theory | Redundancy Effect | Memory | Practice
Why multitasking fails
Students believe they can study whilst listening to podcasts, scroll social media whilst completing homework, or switch between assignments without performance costs. Human brains cannot process multiple complex tasks simultaneously. The brain instead engages in rapid task switching, and each switch requires working memory resources to deactivate the previous context, activate the new one, and eventually switch back. This delays deep focus. Effective learning of cognitively demanding material requires sustained single-task focus.
Splitting attention across tasks contributes to cognitive load through the Redundancy Effect. Many students enjoy listening to music whilst studying, combining calming music with planning lessons, or listening to a podcast during weightlifting, and these combinations can make activities more enjoyable. But the attention is shifting quickly between activities rather than covering both. Reading a book whilst listening to a podcast shows the limit: most readers reach the end of a page having ignored the podcast entirely.
Those with ample working memory capacity may manage switching costs on simple tasks. Students with limited capacity suffer most, since each switch delays refocus. Attempting to multitask fatigues cognitive resources and reduces the ability to manage more than one task.
Research: Rosen 2008
Psychologists interviewed multitaskers, gave them different tasks to accomplish and compared their results with a control group that was instructed to do only one thing at a time. While those who multitasked claimed to feel more productive, they couldn’t do as much and made more mistakes than their unitasking counterparts.
References
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
Monsell, S. (2003). Task switching. Trends in Cognitive Sciences, 7(3), 134-140. https://doi.org/10.1016/S1364-6613(03)00028-7
Ophir, E., Nass, C., & Wagner, A. D. (2009). Cognitive control in media multitaskers. Proceedings of the National Academy of Sciences, 106(37), 15583-15587. https://doi.org/10.1073/pnas.0903620106
Pashler, H. (1994). Dual-task interference in simple tasks: Data and theory. Psychological Bulletin, 116(2), 220-244. https://doi.org/10.1037/0033-2909.116.2.220
Rosen, C. (2008). The myth of multitasking. The New Atlantis, 20, 105-110.
Rubinstein, J. S., Meyer, D. E., & Evans, J. E. (2001). Executive control of cognitive processes in task switching. Journal of Experimental Psychology: Human Perception and Performance, 27(4), 763-797. https://doi.org/10.1037/0096-1523.27.4.763
Sweller, J., van Merriënboer, J. J. G., & Paas, F. (2019). Cognitive architecture and instructional design: 20 years later. Educational Psychology Review, 31(2), 261-292. https://doi.org/10.1007/s10648-019-09465-5