this post was submitted on 06 Oct 2023
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Your brain finds it easy to size up four objects but not five — here’s why (www.nature.com)
submitted 11 months ago by Infrapink@kbin.social to c/science@beehaw.org
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An experiment found that the brain uses one set of neural circuits to identify the numbers 1–4; these circuits are very specific to their own numbers. A separate set of circuits respond to the numbers 5–9; these are less precise, and are activated by adjacent numbers.

For this reason, it is easier to determine when there are four things than to determine there are five things.

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[–] jarfil@beehaw.org 9 points 11 months ago* (last edited 11 months ago) (1 children)

This has been part of IQ tests for a while: the vast majority of people can hold to 4 items without a problem, some people struggle with that, some people can hold to 5, 6, 7 or rarely more objects without a problem.

It's also why phone numbers in most places started as 5 digit numbers, then as "area code + 7", and now that we use smartphone contact lists to save them, they've gone to full "country code + 9 + extension". There was also an interesting movement opposing the changes: https://www.mentalfloss.com/article/61116/why-did-old-phone-numbers-start-letters

[–] rnd@beehaw.org 5 points 11 months ago (1 children)

I bet this is also why old-timey phone numbers encoded the first digits with letters. The US had the famous ABC2/DEF3/... system that's still displayed on most keypads, and the former Soviet Union mapped the first letters of the Russian alphabet (skipping З to avoid confusion with 3)...

[–] JoBo@feddit.uk 3 points 11 months ago (1 children)

I don't think that's why, not least because this is a recent discovery. The reason is, presumably, because 26+ keys are difficult to fit on a small but still usable keyboard.

[–] rnd@beehaw.org 3 points 11 months ago (1 children)

Think you misunderstand me. Long before texting was a thing, landline phones (with rotary dials!) also had letters associated with digits. This layout was later transferred to keypads, which in turn became the SMS layout.

[–] JoBo@feddit.uk 1 points 11 months ago* (last edited 11 months ago)

Yes. And they had letters grouped with the numbers because 26+ keys is a lot to fit on a small but still usable keyboard (or dial, originally).