No Monkeying Around: Chimps Top Humans in Memory Test

By Mary Rose Thomas-Glaser

New cognitive research by primatologists at the Kyoto University Primate Research Institute in Japan revealed a startling finding — young chimps performed remarkably better than adult humans in their ability to memorize numbers and their locations.

In primate-to-primate testing, the recollection skills of university students were pitted against three adult female chimps and their juvenile offspring who had been taught to recognize single-digit numbers prior to testing.

The Tests and the Champs

Testing evaluated the ability of humans and chimps alike to memorize the numbers one to nine as they were rapidly displayed on a touch screen monitor and then quickly obscured with blank white squares. The challenge for each participant was to correctly touch the squares covering the numbers in ascending order.

As testing progressed, the length of time the numbers were displayed decreased from 650 to 430 to 210 milliseconds. In comparison, the average time to blink an eye is 300 to 400 milliseconds.

Results revealed that humans and adult chimps were relatively equal in their ability to accurately recall the location of numbers. The young chimps, however, excelled. At the shortest exposure time, the five-year old chimps had an 80 percent accuracy rate, twice the rate of adult humans.

“We’ve concluded through the cognitive tests that chimps have extraordinary memories,” says Tetsuro Matsuzawa of the Primate Research Institute. “They can grasp things at a glance. As a human, you can do things to improve your memory, but you will never be a match for Ayumu (the young chimp memory champ).”

Eidetic Memory

Researchers concluded that young chimps relied on eidetic or photographic memory. At 210 milliseconds, the duration was too short for eyes to scan the screen. Adolescent chimps were able to take a visual “snapshot” of the screen enabling them to remember numbers with a high degree of accuracy.

In the wild, this ability would enable them to recall locations of fruit or branch patterns in a tree or make split-second decisions under threats.

In rare instances, children possess “photographic” memories, like that of young chimps. But in both children and chimps alike this ability diminishes as they mature. Scientists speculate that eidetic memory of humans was lost as the brain gained complex language capabilities. Interestingly, some children with autism who have verbal language difficulties display similar eidetic memory abilities.

“Observing that other species can outperform us on tasks that we assume we excel at is a bit humbling,” states anthropologist Jill Pruetz of Iowa State University. “Rather than taking such findings as a rare example or a fluke, we should incorporate this knowledge into a mindset that acknowledges that chimpanzees, and probably other species, share aspects of what we think of as uniquely human intelligence.”

Classroom Discussion

• What region of the brain is responsible for memory and language? How does it change as we age?
• What are animals have been found to have remarkable memory capabilities? Research Alex, the African grey parrot, and Koko, the gorilla, to learn about their special talents.