Plus-Minus Task
A mental arithmetic task: add or subtract 3 to numbers as quickly and accurately as possible across three blocks.
Frequently Asked Questions
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Where does this task come from?
It is Jersild's 1927 paradigm, the first systematic demonstration of task switching: adding or subtracting three is slower in alternating blocks than in pure blocks.
How is the switch cost computed?
Typically as the reaction-time difference between mixed blocks (alternating plus and minus) and pure blocks, averaged across the two operations.
Why is alternating slower?
Each trial requires reconfiguring the operative rule — addition versus subtraction — and the residual cost after practice is treated as a window into executive control.
What influences the size of the cost?
Rule complexity, practice, preparation time between trials, and individual differences in control ability; expect tens to hundreds of milliseconds.
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References
- Jersild, A. T. (1927). Mental set and shift. Archives of Psychology, 89, 5-82.
- Spector, A., & Biederman, I. (1976). Mental set and mental shift revisited. The American Journal of Psychology, 89(4), 669-679.
- 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), 49-100. 10.1006/cogp.1999.0734
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About This Experiment
This experiment is an educational adaptation for demonstration purposes. It is not a clinical diagnostic tool. Results reflect your performance in this specific session and should not be interpreted as an assessment of your cognitive abilities.
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