Contextual Information Can Trip Up The Brain On Even The Simplest Logic Problems
December 21, 2013

Why Do Our Brains Sometime Mess Up Simple Calculations?

redOrbit Staff & Wire Reports - Your Universe Online

If the human brain is comparable to a computer, why does it so often make mistakes that its electronic counterpart does not? New research suggests it all has to do with how various problems are presented.

Scientists typically like to make this comparison because both the human brain and a computer typically follow a set of rules in which to make decisions, communicate and perform other tasks. However, University of Wisconsin-Madison cognitive scientist and psychology professor Gary Lupyan said people can get tripped up on even the simplest logic problems because they get caught up in contextual information.

For example, even a simple challenge like determining whether or not a number is odd or even can be tricky, under the right circumstances. Lupyan said that there is a significant minority of people, even if they are well-educated, that can mistake a number such as 798 for an odd number – because, even though deep down we know that only the last number is used to determine whether it is even or odd, we can be fooled by the presence of two odd numbers.

“Most of us would attribute an error like that to carelessness, or not paying attention, but some errors may appear more often because our brains are not as well equipped to solve purely rule-based problems,” the professor, whose work appears in a recent edition of the journal Cognition, explained in a statement Friday.

In multiple trials involving such tasks as sorting numbers, shapes and even people into easy categories like evens, triangles and grandmothers, Lupyan found study participants often broke simple rules based on context.

For instance, when asked to consider a contest that was only open to grandmothers and that each eligible individual had an equal chance of winning, the subjects believed a 68-year-old woman with six grandchildren was more likely to emerge victorious than a 39-year-old female with one single, newborn grandchild.

“Even though people can articulate the rules, they can't help but be influenced by perceptual details,” he explained. “Thinking of triangles tends to involve thinking of typical, equilateral sorts of triangles. It is difficult to focus on just the rules that make a shape a triangle, regardless of what it looks like exactly.”

Lupyan said that in many cases, not only is overlooking these types of rules overly detrimental, but doing so can actually be beneficial when it comes to evaluating unfamiliar things. The lone exception, he said, is when it comes to mathematics, where rules are unequivocally necessary in order to achieve a successful outcome.

“After all, although some people may mistakenly think that 798 is an odd number, not only can people follow such rules – though not always perfectly – we are capable of building computers that can execute such rules perfectly,” Lupyan said. “That itself required very precise, mathematical cognition. A big question is where this ability comes from and why some people are better at formal rules than other people.”

He added this issue could be especially important to math and science teachers: “Students approach learning with biases shaped both by evolution and day-to-day experience. Rather than treating errors as reflecting lack of knowledge or as inattention, trying to understand their source may lead to new ways of teaching rule-based systems while making use of the flexibility and creative problem solving at which humans excel.”