A recent study has found that simians can understand basic aspects of arithmetic as specific cells of their brain respond to certain numerals, indicating that specific human brains might also have a finetuned preference for specific numerical values.
A team of researchers led by Andreas Nieder of the University of Tubingen in Germany taught two rhesus monkeys to count by showing them various dots on a screen followed by Arabic numerals.
The monkeys had to pull a lever to indicate when the numeral matched the preceding count of dots. An accurate response earned them some apple juice, which they consider a treat. The researchers also reversed the task, showing the Arabic numerals several seconds before the dots.
The team recorded the response rate of about 350 neurons located in each monkey’s brain. Of the roughly 700 neurons they examined, 160 appeared to have a strong preference for a specific value between one and four.
Nieder said a given brain cell would send out a barrage of electrical signals whenever the animal saw three dots on the screen or the number three, but the same cell would not respond when the monkey was presented with other numerical values.
The results suggest that individual cells in human brains might also have a fine-tuned preference for specific numerical values.
Liz Brannon at Duke University in North Carolina said the findings support the notion that non-human primates really can understand the meaning of numerals. “Although monkeys do not have language they can understand a symbol and what it refers to,” she told the New Scientist. Nieder, said the monkeys can count to far higher numbers. “I am convinced they could go to infinity,” he said.