Monkey math machinery is like humans'

October 31, 2005

DURHAM, N.C. -- Monkeys have a semantic perception of numbers that is like humans' and which is independent of language, Duke University cognitive neuroscientists have discovered. They said their findings demonstrate that the neural mechanism underlying numerical perception is evolutionarily primitive.

Jessica Cantlon and Elizabeth Brannon described their findings with macaque monkeys in an article published online the week of Oct. 31, 2005, in the Early Edition of the Proceedings of the National Academies of Science. Cantlon is a graduate student and Brannon is an assistant professor in the Department of Psychological and Brain Sciences, as well as a member of the Center for Cognitive Neuroscience. Their work was supported by the National Institute for Child Health and Development, The National Science Foundation and a John Merck Scholars Award.

In their experiments, the researchers sought to test whether monkeys show a phenomenon known as "semantic congruity" when making numerical comparisons.

"When adult humans compare any two things, such as the size of two animals, and they're asked 'which is smaller, an ant or a rat?' one might think it's the same kind of question as 'which is larger, an ant or a rat?'" said Brannon. "But humans are faster at saying an ant is smaller than saying a rat is larger. By contrast, if the two animals are large, such as a cow or an elephant, they're quicker at saying the elephant is larger than saying the cow is smaller. This 'semantic congruity' holds for all kinds of comparisons, including numbers and distances.

"It would seem that this is entirely a linguistic effect, totally dependent on language," said Brannon. "But we sought to understand whether monkeys showed this semantic effect, even though they don't have language."

In their experiments, Cantlon and Brannon presented monkeys with two arrays of randomized numbers of dots displayed on a computer touch screen at randomized positions. However, instead of using language to instruct the monkeys to "choose larger" or "choose smaller" the researchers made the background blue if the monkeys were to choose the larger number and red if the smaller number. The monkeys were rewarded with a sip of a sweet drink for correct answers.

"Our results showed a very large semantic congruity effect," said Cantlon. "For example, when the number pair was small, such as two versus three, the monkeys were much faster at choosing the smaller compared to the larger of the pair. We were also impressed at the high level of accuracy the monkeys achieved on this difficult conditional discrimination," she said.

"Clearly, even though their capability has nothing to do with language, it is nevertheless semantic in that the red and blue color cues carry meaning for the monkeys," said Cantlon.

Brannon said the new findings represent further evidence of the fundamental similarity in numerical thinking in human and non-human primates.

Said Brannon "This is another piece of the puzzle showing us that the comparison mechanism that the monkeys use is, as far as we can tell, the same mechanism that humans are using." More broadly, she said, the findings yield insight into the role - or lack of a role - that language plays in the process.

"The ability to use language is obviously one of the major differences in the way humans and animals function in the world," she said. "However, these experiments clearly show that this semantic congruity effect, which we thought was language-dependent, is not."
-end-


Duke University

Related Language Articles from Brightsurf:

Learning the language of sugars
We're told not to eat too much sugar, but in reality, all of our cells are covered in sugar molecules called glycans.

How effective are language learning apps?
Researchers from Michigan State University recently conducted a study focusing on Babbel, a popular subscription-based language learning app and e-learning platform, to see if it really worked at teaching a new language.

Chinese to rise as a global language
With the continuing rise of China as a global economic and trading power, there is no barrier to prevent Chinese from becoming a global language like English, according to Flinders University academic Dr Jeffrey Gil.

'She' goes missing from presidential language
MIT researchers have found that although a significant percentage of the American public believed the winner of the November 2016 presidential election would be a woman, people rarely used the pronoun 'she' when referring to the next president before the election.

How does language emerge?
How did the almost 6000 languages of the world come into being?

New research quantifies how much speakers' first language affects learning a new language
Linguistic research suggests that accents are strongly shaped by the speaker's first language they learned growing up.

Why the language-ready brain is so complex
In a review article published in Science, Peter Hagoort, professor of Cognitive Neuroscience at Radboud University and director of the Max Planck Institute for Psycholinguistics, argues for a new model of language, involving the interaction of multiple brain networks.

Do as i say: Translating language into movement
Researchers at Carnegie Mellon University have developed a computer model that can translate text describing physical movements directly into simple computer-generated animations, a first step toward someday generating movies directly from scripts.

Learning language
When it comes to learning a language, the left side of the brain has traditionally been considered the hub of language processing.

Learning a second alphabet for a first language
A part of the brain that maps letters to sounds can acquire a second, visually distinct alphabet for the same language, according to a study of English speakers published in eNeuro.

Read More: Language News and Language Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.