Almost all the analog instruments on your car's dashboardâ€“ speedometer, gas gauge, tachometer, temperature gaugeâ€“ rely on a fundamental concept known as the number line. We're so used to the concept of a series of numbers regularly mapped onto a space (linear or otherwise) that the common thinking is that it's just built into our brains. But a new study with an indigenous group in Papua New Guinea suggests otherwise.

Where it is usually believed humans are 'hard-wired' to associate numbers with space, work with the very isolated Yupno tribe has revealed it's a cultural and not innate tool, according to Rafael Nunez, director of the Embodied Cognition Lab and associate professor of cognitive science in the UC San Diego Division of Social Sciences:

"Our study shows, for the first time, that the number-line concept is not a 'universal intuition' but a particular cultural tool that requires training and education to master," Nunez said. "Also, we document that precise number concepts can exist independently of linear or other metric-driven spatial representations."

They presented uneducated Yupno individuals with a series of numbers (or equivalent symbols) and had them place them on a line, with "1" at one endpoint, and "10" (or 100, 1000) at the other. They found that

...unschooled Yupno adults placed numbers on the line (or mapped numbers onto space), but they did it in a categorical manner, using systematically only the endpoints: putting small numbers on the left endpoint and the mid-size and large numbers on the right, ignoring the extension of the line - an essential component of the number-line concept. Schooled Yupno adults used the line's extension but not quite as evenly as adults in California.

So, where we would likely place the numbers on the line like this

1-2-3-4-5-6-7-8-9-10

The Yupno would do this

1234â€”â€”â€”â€”-5678910

... which means, since the Yupno are humans just like you or I, the number-line concept isn't a factory-installed given.

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I was trying to think of other ways to convey information, specifically car dashboard type stuff, without using the number-line concept. It's tricky, but I think I have an idea. Let's use the gas gauge as an example. Instead of the number line we use (0 to 100, that is empty to full), what if we used a single light of varying intensity? Off is empty, bright is full, and the steps in between correspond to how much fuel there isâ€“ I think people would have no issue interpreting that, and that's an analog meter that doesn't rely on a linear visual scale. So maybe the as-yet-unfound Yupno cars use that.

Also interesting is the Yupno's non-body conception of time. They're like us in that they equate the present with themselves (the article brings up the great point about how we almost always point at the ground by our feet when we talk about "now") but unlike most of us who think of the future as "in front" of us and the past as "behind us", Yupno people equate time with the terrain of the valley they live in. Future is uphill, past is downhill, regardless of the direction they're facing.

Neat, huh?