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Showcase 20 · Sense of time

How long was that?

Two short sequences play one after the other, without a clock or progress bar. One barely changes, the other changes constantly. Afterwards, estimate how long each one was and which felt longer. Only then does the clock show what really passed.

The experiment needs JavaScript. The explanation below is readable without it.

How it works

Both sequences show the same grid of shapes and last exactly the same time. The duration is picked between six and ten seconds for each run and only named after your answer. In one sequence the grid changes only twice, in the other about every half second, always just one shape and without flashes. Chance decides which comes first. Timing uses the browser's clock. If a sequence is interrupted, by pausing, scrolling away or switching tabs, the run starts over, so you only compare sequences you watched completely.

Research on time perception describes both directions: in hindsight, an eventful span often seems longer because more of it stays in memory. When you pay attention to time while watching, on the other hand, an uneventful span often feels longer. Whether and how this shows up for you cannot be predicted. The experiment says something about how the brain estimates duration, not about physics: that time can feel different does not prove that it does not exist. Your answers stay in this window; nothing is stored or sent.