Orangutans at DC Zoo Demonstrate ‘Sequential Learning’

Primate keepers at the National Zoo in Washington, D.C., replicate a chimpanzee based study from Kyoto University, Japan, on Orangutans to understand the intelligence of different species.

Bonnie plays the ‘sequential learning’ game while a primate keeper explains how it works.

Orangutans have spatially based memory systems, says an expert on the primate.

“It’s almost like they have a photographic memory,” a primate keeper at the National Zoo for the past 15 years, Erin Stromberg, says.

The primate keepers at the National Zoo study the Orangutans performance at a memory based game designed by the Primate Research Insitute at Kyoto University in Japan, and compare them to results the Institute recorded from Chimpanzees, to compare the differences between the species, Stromberg says.

Physical representations of different animals brains demonstrate the size of the Orangutans brain compared to others. The Orangutans brain is the second from the left, followed by a human brain.


An interactive exhibit in the Think Tank lets people try the sequential memory game the Orangutans play.
The Orangutan Bonnie, who is 40 years old, licks her finger after eating a small bunch of purple grapes as a reward for successfully playing the memory sequence game at the National Zoo.

The game – which primate keepers supervise at the Think Tank exhibit – challenges the Orangutans by flashing numbers from one to nine across a touch screen. After a couple of seconds, the numbers disappear, and gray scale boxes replace them.

The Orangutans are then challenged to identify the numbers in sequence.

At the National Zoo, primate keepers reward success with treats. The Orangutan playing Monday, Bonnie, likes purple grapes, Stromberg says.

When the Orangutans get the sequence incorrect, the touch screen turns red, and a loud buzzer goes off.

The Orangutans progressively work through the game, until they can remember all nine numbers and identify them in the correct order.

A painting of an Orangutan prominently featured in the Think Tank exhibit at the D.C. National Zoo.

There are seven Orangutans at the National Zoo, one of whom is a child, all six adults participate in the study.

Stromberg says the Chimpanzees in the original Kyoto University study can outperform the Orangutans.

The Chimpanzees can play the game with black numbers, Stromberg says, while the Orangutans need colors to help them remember the patterns.

The differences in how the Orangutans play the game compared to Chimpanzees don’t matter, Stromberg says.

Different species excel at different things, Stromberg says, and the Orangutans results teach researchers how their brains work.


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