Sensory Memory Experiment (Iconic Memory)
Your eyes see far more than your mind can report. This classic task, inspired by George Sperling's 1960 experiments, flashes a grid of letters for a fraction of a second and asks you to recall them — all of them, or just one cued row.
Frequently Asked Questions
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What is iconic memory?
Iconic memory is the visual form of sensory memory. It briefly holds a near-photographic snapshot of a visual scene for roughly a quarter to half a second after the stimulus disappears, before the information either fades or is transferred into working memory.
What did Sperling's partial report experiment show?
Sperling (1960) showed that when people report all letters from a flashed grid they manage only about 4 of 12, but when cued to report just one random row they recall nearly all 4 letters of that row. Because the row was chosen after the display vanished, the whole grid must have been briefly stored in iconic memory — suggesting a capacity of roughly 4-5 items that decays within half a second.
Why is partial report accuracy higher than whole report?
Whole report forces you to name 12 letters before the trace fades, so much is lost during verbal output. Partial report asks for only 4 letters, which can be read out of iconic memory before decay — revealing how much information the sensory trace actually held.
Is this experiment diagnostic?
No. This is an educational demonstration of a classic cognitive paradigm, not a diagnostic tool. Your scores depend on attention, practice, and screen conditions, so treat them as a personal illustration of iconic memory rather than a measure of ability.
Show Details
What is Sensory Memory?
Sensory memory is the briefest stage of memory, holding raw sensory information for a fraction of a second after the stimulus disappears. Iconic memory is the visual form of sensory memory. It holds an almost photographic snapshot of what you see, but it fades within about half a second — which is why a flash of letters can feel vivid yet vanish almost instantly.
Sperling's 1960 Experiments
George Sperling flashed 3×4 grids of letters for only 50 milliseconds. In the whole report condition, participants could report only about 4 of 12 letters. In the partial report condition, a cue indicated which row to report after the grid vanished — and participants could recall almost all 4 letters of the cued row. Because the cued row was chosen randomly, the success implies the entire grid was briefly available in iconic memory, with an estimated capacity of roughly 4-5 items.
Practical Implications
Iconic memory explains why we can follow fast-moving scenes, read quickly, and integrate frames of a movie into continuous motion. It also shows the limits of attention: the raw snapshot is large, but only a small portion can be transferred into working memory before it fades. Chunking and selective attention help you make the most of this fleeting buffer.
References
- Sperling, G. (1960). The information available in brief visual presentations. Psychological Monographs: General and Applied, 74(11), 1-29. 10.1037/h0093759
- Sperling, G. (1963). A model for visual memory tasks. Human Factors, 5(1), 19-31.
- Averbach, E., & Coriell, A. S. (1961). Short-term memory in vision. Bell System Technical Journal, 40(1), 309-328. 10.1002/j.1538-7305.1961.tb03987.x
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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.
Data Privacy
Your experiment data is processed and stored locally in your browser. No data is uploaded to any server unless you explicitly export it.
