From the desk of: Carol L. Cheatham, Ph.D.
As a developmental cognitive neuroscientist, I’m always interested in learning about studies that will inform my work. Recently, I attended the International Conference on Infant Studies where I heard a scientist speak about his research with non-human primates (i.e., monkeys). The studies that he described weren’t just informative—his results stopped me in my tracks! Since I returned home, I have been reading all his papers and I’m excited to share his findings.
In Japan, a scientist by the name of Tetsuro Matsuzawa has been working for 30 years with Ai, a chimpanzee and her offspring. Ai learned at an early age to recognize symbols on a keyboard and to name objects and colors. She and her kids have also been taught numbers and number order. For one number task, these chimpanzees are trained on a touch screen. Numbers from 1 to 9 are presented on a screen in random order and in random places on the screen. The chimps touch the numbers in ascending order to receive a treat.
This is a truly impressive feat in and of itself, however, more amazingly, these chimps can still successfully complete the task when the numbers on the screen disappear behind white boxes the instant they touch the number 1! Let me say that again: the numbers from 1 through 9 come up on the screen in random order and in random places. The chimp’s job is to touch the numbers in order. The instant that the chimp touches the number 1 (see photo A), the other numbers disappear behind white boxes (see photo B), and the chimp must finish the task basically blind. The chimps in this “masked” task are still successful even though they only saw all nine numbers for a split second. To put this in perspective, humans who are tested on this masked task can only touch the first three or four numbers correctly. Mind you, this skill cannot be taught. The brain has to encode the numbers and their positions in a flash and be able to recall the position of numbers. Why don’t humans have such a flash memory? Dr. Matsuzawa hypothesizes that language gets in our way. Basically, our brains get bogged down by attaching words to the numbers—a problem that the chimps do not have!
You can watch the chimps perform both the numbers and masked numbers tasks here. There are also videos of human subjects attempting the same tasks, but with far less success.
Finding out about this research has had me devising ways to test it in humans as well as trying to explain it in chimps. Why would chimps need flash memory? Can the human brain work similarly? How would we test that question when our lives are so tied to language? As I continue my work in cognitive development and decline, I will ponder Dr. Matsuzawa’s work with these chimpanzees and their extraordinary recall ability.
