IT has long been known that chimpanzees have good long-term memories, but now new research involving Scottish scientists shows that chimpanzees have working memories too.

Working memory is the part of short-term recall which is concerned with immediate conscious perceptual and linguistic processing. Humans use working memory for comprehending, processing and manipulating information.

Little was known about the working memory of our nearest relative, but now scientists at St Andrews University have joined with colleagues from the Max Planck Institute for Evolutionary Anthropology and Austria’s University of Veterinary Medicine to show that chimps have the working memory similar to a seven-year-old human child.

They have concluded that chimpanzees’ working memory capacity is “not fundamentally different” from the human capacity, overturning most previous theories.

The study reported: “Chimpanzees exhibited performance levels comparable with human school-age children ... (while performing) an intuitive working memory task that does not rely on extensive training.”

“Our findings suggest that chimpanzees perform similar to seven-year-old children in an intuitive working memory task that does not rely on extensive training.”

Inside Ecology explained the experiments: “Researchers presented chimpanzees with a task to search for food in a number of small, opaque boxes. The chimpanzees first watched how pieces of food were hidden in these boxes. Then they could start to search for the food items by pointing at these boxes one by one.

“If a chosen box contained food, the chimpanzees received this food reward. After each choice, the boxes were covered for 15 seconds.

“To retrieve all of the food items chimpanzees needed to keep in mind which boxes they had already searched for food.

“The researchers increased the difficulty of the task depending on the ability of each chimpanzee by increasing the number of boxes and by shuffling the boxes between each search. The study revealed key similarities between chimpanzee and human working memory: the best-performing chimpanzees remembered at least four items, one young chimpanzee more than seven items.

“They used both the appearance of the boxes as well as their position to remember their previous choices.”

Inside Ecology added: “Humans typically perform worse in working memory tests if they need to do something in parallel. Likewise, if the chimpanzees had to perform a second, similar task in parallel, their performance declined. Differences in working memory ability between chimpanzees were stable over months.

“The most obvious difference between chimpanzees and humans was not the working memory capacity but the search strategies that humans typically employ to facilitate this task: chimpanzees did not come up with the idea to search the boxes in line from one side to the other.”

The study concluded: “These findings show remarkable similarities between human and chimpanzee working memory abilities despite evolutionary and life-history differences.

“However, this direct comparison might be hampered by the processing strategies that humans typically adopt in these tasks and that can reduce the memory load.

“The search strategies (or the lack thereof) seem to be a more promising candidate for a dividing line between humans and chimpanzees than memory capacity per se.

“Future work might further explore how such processing strategies develop and to what extent they can also be found in non-human animals.”