Approximate Number Sense

We focus a lot on literacy here at Be Amazing Learning, but at our core, we’re about the brain and how to make it operate most efficiently. So anything about the brain is going to pique our interest. This week, it’s the concept of an approximate number system.

Our approximate number system our instinctive ability to represent numbers. It’s what we use to find the shortest check-out line at the grocery store. And, as the New York Times reported, it’s:

an ancient and intuitive sense that we are born with and that we share with many other animals. Rats, pigeons, monkeys, babies — all can tell more from fewer, abundant from stingy. An approximate number sense is essential to brute survival: how else can a bird find the best patch of berries, or two baboons know better than to pick a fight with a gang of six?

Our approximate number sense is different from the ability to “do” math (or, as the Times says, “the ability to manipulate representations of numbers and explore the quantitative texture of our world”). “Doing” math is a uniquely human and very recent skill:

People have been at it only for the last few millennia, it’s not universal to all cultures, and it takes years of education to master.

However, research indicates a strong correlation between the innate approximate number sense and our learned ability to do math. In a 2008 study in the journal Nature, Justin Halberda and Lisa Feigenson of Johns Hopkins University and Michele Mazzocco of the Kennedy Krieger Institute in Baltimore devised a test of approximate number sense.

Comparing the acuity scores with other test results that Dr. Mazzocco had collected from the students over the past 10 years, the researchers found a robust correlation between dot-spotting prowess at age 14 and strong performance on a raft of standardized math tests from kindergarten onward. “We can’t draw causal arrows one way or another,” Dr. Feigenson said, “but your evolutionarily endowed sense of approximation is related to how good you are at formal math.”

The researchers don’t know yet how the two number systems interact:

Brain imaging studies have traced the approximate number sense to a specific neural structure called the intraparietal sulcus, which also helps assess features like an object’s magnitude and distance. Symbolic math, by contrast, operates along a more widely distributed circuitry, activating many of the prefrontal regions of the brain that we associate with being human. Somewhere, local and global must be hooked up to a party line.

Want to test your approximate number sense? The Times has an interactive screening similar to the test of acuity used in the Nature study.

(Hat tip to Scientific Learning’s Brain Gain email series for this topic.)

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