Change Detection
Remember a colored array, judge change after delay; estimate K and hit/false alarm. Includes export.
Frequently Asked Questions
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Overview
Remember a colored array and judge whether it changes after a delay, estimating working-memory capacity (K) and hit/false-alarm rates.
How to operate
View the sample array, retain it over a delay, then decide change/no-change for the test array. Accuracy and decisions are logged.
How many items can I hold?
Change-detection studies place visual working-memory capacity at roughly 3-4 simple items for most adults — the classic estimates from Luck and Vogel's research.
What is change blindness?
The striking failure to notice large changes when they coincide with a flicker or other disruption — proof that seeing a scene is not the same as encoding it.
Why does this matter outside the lab?
Drivers missing a pedestrian after a glance away, editors missing typos on rereading, and radiologists missing changes between scans all trace back to the same capacity and encoding limits.
Show Details
Introduction
The task probes visual working-memory by judging change after a delay. A common approximation is K = set size × (hit rate − false-alarm rate), reflecting the number of items concurrently maintained.
Each trial: 1) sample array shown ~800ms; 2) blank delay ~800ms; 3) test array; 4) respond change/no-change. Set sizes {2,4,6,8}, each repeated 8 times (total 32 trials).
Colors drawn from a fixed palette without repetition; the test array changes one item with 50% probability (random position and color) or stays identical. Conditions are balanced to minimize strategic responding.
Per-trial index, set size, changed flag, response, correctness; accuracy by set size; hit/false-alarm counts; K estimated from the largest set size. Results are exportable for verification and analysis.
Adjustable delay, trial counts, and set-size range. Current defaults: setSizes = [2,4,6,8]; trialsPerSize = 8; delayMs ≈ 800.
References
- Luck, S. J., & Vogel, E. K. (1997). The capacity of visual working memory for features and conjunctions. Nature, 390(6657), 279-281. 10.1038/36846
- 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.
- Zhang, W., & Luck, S. J. (2008). Discrete fixed-resolution representations in visual working memory. Nature, 453(7192), 233-235. 10.1038/nature06860
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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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