Computer tests show that apes are no monkeys over memory

The animals’ memory skills go beyond simply recognising previously seen images.

Unlike recognition, recall demonstrates an ability to remember things not present “at the moment”. It is necessary for planning and imagining and contributes to complex social behaviour and thinking skills.

Scientists showed that five rhesus monkeys could reproduce simple figures on a touch screen from memory.

The shapes included two or three boxes in a grid. When they were shown part of a shape, the monkeys had to “draw” in the rest of the image by touching the right locations.

Dr Benjamin Basile, from Atlanta’s Emory University in the US, said: “The ability of monkeys to recall these shapes flexibly suggests that they might be able to recollect other types of information that would be useful to them in the wild.

“It’s exciting to speculate that they may be able to recollect the appearance of monkeys they know, what favourite foods look like, or the path they would have to take to get to a water source.”

The findings are published this week in the journal Current Biology. They suggest that recall ability does not depend on language and may have been present in the common ancestor of monkeys and humans 30 million years ago.

Like humans, the monkeys remembered less in recall than in recognition tests. Recall performance also deteriorated slowly over time.

Importantly, the animals were able to transfer their memory skill to novel shapes. They were not only able to recall shapes they had seen during training.

Previous studies have shown that recall and recognition in humans require different types of memory.

The scientists wrote: “Recollection and familiarity likely evolved because they solved functionally incompatible problems. For example, familiarity does not support detailed memory for context, but it is quick and resistant to distraction.

“Recollection is slower and more vulnerable to distraction but supports a more detailed and flexible use of memory.

“Familiarity might better allow rapid responses to foods and predators under distracting conditions, whereas recollection might be necessary to access knowledge of distant food locations or past social interactions for planning future behaviour.