Our brains stumble on even the simplest rule-based calculations, researchers have shown.
Research by Gary Lupyan, a cognitive scientist and psychology professor at the University of Wisconsin-Madison, shows humans get caught up in contextual information, even when the rules are as clear-cut as separating even numbers from odd.
Almost all adults understand that it's the last digit - and only the last digit -that determines whether a number is even, including participants in Lupyan's study. But that didn't keep them from mistaking a number like 798 for odd.
A significant minority of people, regardless of their formal education, believe 400 is a better even number than 798, according to Lupyan, and also systematically mistake numbers like 798 for odd. After all, it is mostly odd, right?
Asked in experiments to sort numbers, shapes, and people into simple categories like evens, triangles, and grandmothers, study subjects often broke simple rules in favor of context.
Lupyan said that even though people can articulate the rules, they can't help but be influenced by perceptual details, asserting thinking of triangles tends to involve thinking of typical, equilateral sorts of triangles.
He said that it is difficult to focus on just the rules that make a shape a triangle, regardless of what it looks like exactly.
The work has been published in the journal Cognition.