How the Human Brain Contends With the Strangeness of Zero
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Zero, which was invented late in history, is special among numbers. New studies are uncovering how the brain creates something out of nothing.
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“Zero is, by many mathematicians, definitely considered one of the greatest — or maybe the greatest — achievement of mankind,” said the neuroscientist Andreas Nieder(opens a new tab), who studies animal and human intelligence at the University of Tübingen in Germany. “It took an eternity until mathematicians finally invented zero as a number.”
Perhaps that’s no surprise given that the concept can be difficult for the brain to grasp. It takes children longer to understand and use zero than other numbers, and it takes adults longer to read it than other small numbers. That’s because to understand zero, our mind must create something out of nothing. It must recognize absence as a mathematical object.
In recent years, research started to uncover how the human brain represents numbers, but no one examined how it handles zero. Now two independent studies, led by Nieder and Barnett, respectively, have shown that the brain codes for zero much as it does for other numbers, on a mental number line. But, one of the studies found, zero also holds a special status in the brain.
“The fact that [zero] represents nothing is a contradiction in itself,” said Carlo Semenza(opens a new tab), a professor emeritus of neuroscience at the University of Padua in Italy who wasn’t involved in either study. “It looks like it is concrete because people put it on the number line — but then it doesn’t exist. … That is fascinating, absolutely fascinating.”
The new studies are the first to reveal what goes on in the brain when a person thinks about zero, and they bring up broader questions about how the mind handles absence — a pursuit that would have pleased Jean-Paul Sartre, the 20th-century existentialist who claimed that “nothingness carries being in its heart.”
What Makes Zero Special
Nieder’s team found some differences between the way the brain represents zero and the way it handles other numbers. For one thing, more neurons had zero as their preferred number than any other small number. Because there are more neurons that code for zero, the brain can represent the empty set with more accuracy than it can represent other small quantities, they found.
“Zero is encoded together with other small numbers, but it is represented more distinctly compared to them,” Nieder said. “It is simply an eccentric outlier and represented as such in the brain.”
