Human predictability and the tendency towards certain patterns // Why does everyone prefer the number 7?

[u/Nekorlsz]

Hello everyone from r/askmath. Anyone else here interested in statistics? Actually, what I wanted to talk about also has A LOT to do with psychology and human social behavior.

A few days ago, I watched a video that introduced me to a rather strange question. According to the video, if you ask people to randomly pick any number between 1 and 10, they’re more likely to choose 7. Have you ever noticed this? Apparently, it’s also the most commonly chosen number when people are asked about their favorite number.

The explanation behind this phenomenon is that, when asked to make a random choice, people immediately rule out 1 and 10 because they’re at the extremes and don’t feel random to whoever’s making the choice. Then 5 gets ruled out because it’s right in the middle and doesn’t feel random either. After that come the even numbers, since the human brain associates a sense of order with multiples of 2 and therefore doesn’t consider them very random.

My theory is that the brain does the same thing with multiples of all integers, just to a lesser extent as the integers get larger. Therefore, odd prime numbers should be perceived by the brain as more random. We can rule out 2, since it never really became part of our intuitive understanding of prime numbers in this context, for obvious reasons.

Finally, we’re left with 3 and 7, and 3 gets picked less often because it’s smaller, so 7 wins in the end.

I didn’t find that chain of reasoning particularly convincing, so I decided to do a little experiment of my own to check whether the claim actually held up. I asked several people I know to give me a random number between 1 and 10.

Before getting into the results, I should mention that they shouldn’t be taken too seriously. Anyone with a basic understanding of statistics knows that such a small sample size, the bare minimum for this kind of analysis, isn’t enough to draw conclusions about a larger population.

As expected, 7 won, but it didn’t just get the expected majority of 45% but it blew past that figure, reaching 60%.

On top of that, 3 came in second place, which continues to support our hypothesis. The numbers at the extremes were among the least popular choices, just as predicted.

These two odd prime numbers (3 and 7), which account for only 20% of all the possible numbers, were chosen by 80% of the people. The third-place number was 6 (10%). All the remaining numbers were chosen equally often.

Of course, people might have their own perfectly valid personal reasons for loving the number 7 that have nothing to do with psychosocial patterns. But given these results, it’s clear that the majority of people who would choose 7 are incredibly predictable within this particular context.

But hey, it’s “just” a choice between 1 and 10, right?

It’s just curious to see this trait in people who say they don’t want to be part of the crowd and who tend to show a certain degree of individualism most of the time. And it’s also curious that they haven’t noticed this pattern yet... even though it’s followed by the majority and is so obvious to anyone, or at least, it should be!

[u/ctoatb]

It varies by culture. The number 7 is lucky in the US while 13 is unlucky. On the other hand, 8 is lucky in China while 4 is unlucky

[u/norrisdt]

You might really enjoy behavioral economics as a topic, and I recommend Kahneman's Thinking Fast and Slow as an accessible introduction.

[u/Bounded_sequencE]

It's just a cultural thing, that became its own thing over time.

It's very easy to break free of, if you think about it critically.

[u/AdityaTheGoatOfPCM]

I'd reckon it's a cumtural phenomenon than an actual thing that applies to all humans of sorts, I mean if you're from the west then the numbers seven and three are religiously associated in culture and are often considered lucky/significant numbers whereas in the east the number significances are completely different with astrology and cosmic fortunes being a major factor. So if you were to hypothetically take around a billion people distributed uniformly accross the world, it is more likely than not that the generalization won't hold.

[u/JJkushbig]

" I watched a video that introduced me to a rather strange question. According to the video, if you ask people to randomly pick any number between 1 and 10, they’re more likely to choose 7. Have you ever noticed this?"

another variation might make it better. tell them that there is a random number chosen for them between 1 and 10, and then ask them what would be that number. it might reduce their bias from automatic thoughts.

I would also like to point out that it is possible that personal experience also shape people's attitude towards numbers. imagine in school/work you are always in the 18th rank/place of something, and as time goes by you notice 18 more than before. another one is being bombarded that 13 brings bad luck, without questioning why you naturally avoid 13 and realize it was not a a deliberate and conscious decision.

[u/bayesian13]

people are primed to think of 7 because of the 7 day week.

Why do we have 7 day weeks? well months are 28 days because the lunar cycle is approximately that long. and dividing that in half makes sense cuz its easy to see when the moon is half full. and then dividing that in half to get "quarter moons" is pretty easy as well.

[u/Uli_Minati → u/bayesian13]

You also have 2 in a couple, hopefully eat 3 meals, experience 4 seasons, have 5 fingers and 6 grades in school. Why would the days in a week be any more memorable than these? Can't think of anything very common related to 8 or 9, though.

[u/Bounded_sequencE → u/Uli_Minati]

Modern cell phone numbers usually have 8 digits (not counting the regional prefix).

[u/Uli_Minati → u/Bounded_sequencE]

You're right, although I would sooner think of specific digits in a specific phone number than how many there are!

[u/Nekorlsz → u/Uli_Minati]

Great point!