Introducing the brain: number sense estimates (Introduction)

by David Turell , Thursday, November 09, 2023, 20:51 (169 days ago) @ David Turell

The key is number four:

https://www.quantamagazine.org/why-the-human-brain-perceives-small-numbers-better-20231...

'More than 150 years ago, the economist and philosopher William Stanley Jevons discovered something curious about the number 4. While musing about how the mind conceives of numbers, he tossed a handful of black beans into a cardboard box. Then, after a fleeting glance, he guessed how many there were, before counting them to record the true value. After more than 1,000 trials, he saw a clear pattern. When there were four or fewer beans in the box, he always guessed the right number. But for five beans or more, his quick estimations were often incorrect.

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"Now, a new study in Nature Human Behaviour has edged closer to an answer by taking an unprecedented look at how human brain cells fire when presented with certain quantities. Its findings suggest that the brain uses a combination of two mechanisms to judge how many objects it sees. One estimates quantities. The second sharpens the accuracy of those estimates — but only for small numbers.

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"The ability to instantly judge the number of items in a set doesn’t have anything to do with counting. Human infants have this number sense even before they learn language. And it’s not limited to humans: Monkeys, bees, fish, crows and other animals also have it.

"A monkey needs to be able to quickly judge the number of apples in a tree, and also how many other monkeys it’s competing against for those apples. A lion, when confronted by other lions, has to decide whether to fight or flee. Honeybees need to know which area has the most flowers for foraging. A guppy has better chances of escaping a predator if it joins a shoal. “The bigger the shoal, the safer that little fish is,” said Brian Butterworth, a cognitive neuroscientist.

"This innate number sense is therefore critical to survival, increasing an animal’s chances of finding food, avoiding predators and ultimately reproducing. “It simply pays off for the survival of an animal to be able to differentiate numeric quantities,” said Andreas Nieder, the chair in animal physiology at the University of Tübingen in Germany, who co-led the new study. The fact that this ability is found in diverse animals, from insects to humans, suggests that it arose a long time ago, and its neural basis has interested cognitive scientists for decades. (my bold)

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"Nieder and Mormann launched a new study to find out how the neurons represent odd and even numbers. The researchers recruited 17 epilepsy patients and showed them flashes of dots, ranging in number from one to nine, on computer screens. The participants indicated whether they saw an odd or even number while electrodes recorded their brain activity.

"Over the next few months, as Esther Kutter, a graduate student studying with Nieder, analyzed the resulting data, she saw a clear pattern emerge — right around the number 4.

"The data, which comprised 801 recordings of single neurons firing, showed two distinct neural signatures: one for small numbers and one for large. Above the number 4, the neurons’ firing for their preferred number grew progressively less precise, and they erroneously fired for numbers close to the preferred one. But for 4 and below, the neurons fired precisely — with the same small amount of error whether firing for one, two, three or four objects. The misfiring in response to other numbers was largely absent.

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“'This boundary popped out in different ways,” Nieder said. The neural patterns suggested that there is an additional mechanism that suppresses smaller-number neurons from firing for the wrong numbers."

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"However, one more major uncertainty remains. The researchers didn’t study the prefrontal or parietal cortices, where the majority of number neurons are located in monkeys. Instead, because of where the patients’ electrodes were inserted, the study focused on the medial temporal lobe, which is involved in memory.

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"It’s not clear why number neurons are present in this region, Butterworth said. “The things that we thought were specific to the parietal lobe seem to be reflected also in parts of the medial temporal lobe.”

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"The level of analysis is “just really outstanding,” said Marinella Cappelletti, a cognitive neuroscientist at Goldsmiths, University of London. The researchers provide “compelling evidence” for dual mechanisms in the medial temporal lobe. She thinks it would be valuable, however, to see whether these mechanisms operate in other brain regions as well, if the opportunity presents.

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"People use numbers frequently and in a variety of ways, and we and our ancestors have used math to describe the world for millennia. In that sense, math is a fundamental part of being human.

"And, as this study starts to show, this calculation prowess might all stem from a finely tuned network of neurons in the brain."

Comment: Counting for survival is an obvious point. Animal counting is no surprise. I would guess the small numbers to four is designed into the brain for survival, and large numbers are an addition we humans have added.