A pair of dot clouds flashes for less than a second — one has more than the other. Tap left or right for the side with more. You don’t count. You feel it. That feeling is a real cognitive system.
The Science: Measures the Approximate Number System (Dehaene, 1997; Halberda and colleagues, 2008). Present in infants, non-human primates, and even fish — an ancient magnitude-comparison mechanism, tuned by education but never fully replaced by counting.
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