Study finds all people, and even monkeys, share similar thought patterns

Each person is a unique individual in their own right, but a groundbreaking new study is offering up considerable evidence that all humans are ingrained with similar thought patterns. Moreover, when a group of monkeys was included in the research, they too displayed similar ways of thinking and ordering ideas (to varying degrees).

All in all, the study’s authors say their work provides some much-needed insight into the development of human languages dating back to the beginnings of our species. These are no small conclusions; this study suggests human and monkey thought patterns are far more similar than previously thought.

This study was a collaboration between Harvard University, UC Berkeley, and Carnegie Mellon University.

From the Amazon to Ohio, regardless of an individual’s age, gender, culture, background, and even species (human/monkey), the research team observed similar thought patterns among a group of diverse participants. A total of 100 subjects took part in the research. That group included indigenous Tsimane people from the Amazon rainforest in Bolivia, both U.S. adults and children, and macaque monkeys.

More specifically, all of the participants displayed a natural tendency toward “recursion.” Recursive thinking essentially describes the ability to think about thinking. That probably sounds confusing, but recursion is what allows humans to arrange words, symbols, or phrases to communicate complex messages or ideas.

“For the first time, we have strong empirical evidence about patterns of thinking that come naturally to probably all humans and, to a lesser extent, non-human primates,” says study co-author Steven Piantadosi, a UC Berkeley assistant professor of psychology, in a press release.

While researchers were expecting to see similar recursive tendencies among human subjects, they were shocked to see how quickly monkeys took to recursive tasks as well.

“Our data suggest that, with sufficient training, monkeys can learn to represent a recursive process, meaning that this ability may not be as unique to humans as is commonly thought,” says study co-author Sam Cheyette, a Ph.D. student in Piantadosi’s lab.

Recursive phrases, often called “nested structures” in the world of linguistics, may provide an easier understanding of recursion. Consider this sentence: “The dog that worried the cat that killed the rat that ate the malt that lay in the house that Jack built.”

What dog is being described in the above sentence? Well, the dog that worried the cat. And, which cat is that? The cat that killed the rat, and on and on. This all may seem incredibly simple, but the ability to understand and order all of those smaller ideas into a larger sentence is an example of recursion.

So, 10 US adults, 50 US preschoolers or kindergarteners, 37 members of the Tsimane tribe, and 3 monkeys were gathered for this study. Each participant was trained to memorize a series of abstract symbols in a particular order. For example, { ( ) } or { [ ] }. These combinations were intended to mimic the nested structures as described above.

Both American participants and monkeys used a big touch screen to learn, memorize, and recall the patterns. If a subject successfully recalled a piece of a pattern a ding would go off, if they made a wrong move a buzzer sound would play, and if an entire sequence was correctly replicated a chime would play. The monkeys also got some food or juice for making the right choices.

The Tsimane’ participants, meanwhile, weren’t as familiar with modern technology. So, they were given index cards and verbal guidance instead.

Next, all participants were told to arrange in the correct order a series of four images from different patterns shown in a random order so that they would make a certain degree of sense. So, let’s say they were shown ( } ( {. The correct, recursive way to rearrange those symbols would be { ( ) }.

While the results weren’t all exactly the same, for the most part, all of the participants were able to arrange the provided symbols in a recursive manner. This is especially noteworthy considering the “Tsimane’ adults, preschool children and monkeys, who lack formal mathematics and reading training, had never been exposed to such stimuli before testing,” the researchers write.

“These results are convergent with recent findings that monkeys can learn other kinds of structures found in human grammar,” Piantadosi adds.

This research speaks to the very essence of what makes us human and separates man from beast. Beyond experiences, education, or cultural impressions all humans are born with the ability for recursive thought. Perhaps even more importantly, we now have scientific evidence that our closely related evolutionary ancestors share similar cognitive abilities.

The full study can be found here, published in Science Advances.