Ape versus machine: Do primates enjoy computer games?
A chimp genius can complete a computer memory test in less time than it takes the average person to blink - and much faster than any human rival. But do the world's cleverest animals enjoy these cognitive tasks?
Ayumu, who was born and raised in Japan's Kyoto University, can remember the location and order of a set of numbers in record time. Sixty milliseconds to be precise.
Of course, it is not "natural" behaviour for a chimp to interact with a computer screen, but scientists suggest this type of task could be good for captive apes.
"Unfortunately, captive great apes often exhibit behavioural signs of boredom, frustration and stress," says Fay Clark from the Royal Veterinary College's Centre for Animal Welfare.
Working with the Zoological Society of London, Ms Clark has recently published a review of research investigating whether challenges that get captive apes thinking can enhance their well-being.
"If an ape does not receive enough cognitive challenge in life, this can lead to abnormal behaviours or a lack of interest in the environment," she tells BBC Nature.
"The key is for scientists to develop challenges which are relevant, motivating, and ultimately solvable if they are going to be used as enrichment."Chimp's challenge
Killer whale: Different pods have developed unique "dialects". A killer whale calf is most likely to learn a dialect from its mother.
Chimp: Wild chimpanzees use at least 66 distinct gestures to communicate with each other.
Octopus: The creatures have been filmed scooping up halved coconut shells and using them as shelters.
Carrion crow: Drop hard nuts on to roads and collect the food after passing cars have cracked them.
Dolphin: Dolphins often make "play" activities more challenging for themselves as time goes on, research suggests.
Otters: Pass down shell-cracking skills to their young. It can take a pup six months to learn how to crack a shell against a stone rested on its belly.
Sumatran orangutan: Observed using objects as tools, including leaves as "toilet paper", large leaves as "umbrellas" and modifying sticks to gather insects.
As one of the world's longest-running laboratory-based studies of chimpanzees, the Ai Project has been investigating chimp intelligence for over 30 years.
Professor Tetsuro Matsuzawa began his research with a one-year-old female chimp Ai, the namesake of the project, in 1977.
Over the years the team investigated Ai's brain power by observing her as she learned to complete tasks including number and object recognition.
In 2000, Ai gave birth to a son, Ayumu, who has since become the number-crunching star of the study, and features in the series Super Smart Animals, for BBC One and the Discovery Channel.
Ayumu's daily routine resembles that of many 11-year-olds: sleep, eat, play and learn.
During his "study sessions" he receives a treat every time he correctly remembers the location of the numbers on screen and selects them in order.
"Ayumu and others can do the task with social praise. Food reward is not the essential matter," Prof Matsuzawa says.
He says the chimps all go to the testing room of their own free will, and "they love to do so".
"It is not only Ayumu but also the other young ones who have the better memory than naive human adults," he says.
Because great apes are "highly individual", it is important to tailor challenges to them, says Ms Clark.
"Some will not be motivated to interact with computer screens," she says. "Some are highly motivated by food rewards; some by human contact."
At Zoo Atlanta in Georgia, US, a group of orangutans are being closely watched. In 2007, a touch screen cunningly disguised in a tree was installed in their enclosure.
"We have specific programmes to look at how they learn," says Dr Tara Stoinski, who leads the study. "They are not games, [the orangutans] are doing problem-solving."
The apes currently have the opportunity to match symbols to photographs on the screen and their moves are studied by researchers at Emory University.
When they correctly categorise a photograph they are rewarded with a small pellet of food.
"It's not like they're getting jackpot of sweets," says Dr Stoinski, who explains that the orangutans are content to interact with the screen even when the dispenser runs out of pellets.
"For some of them it is inherently rewarding," she tells BBC Nature.
The research team say they have made careful observations to ensure the apes are not negatively influenced by the presence of the "learning tree".
"We were aware that introducing the tasks could cause competition in the group which could have negative effects - it could create some tension.
"So we evaluated it from that standpoint but we didn't find that.
"Our animals they seem to be very happy with the division of labour."
In contrast to the "undercover" enrichment in Atlanta, orangutans in Milwaukee County Zoo, Wisconsin have been presented with the latest in modern technology.Apes with iPads
Last Christmas, charity Orangutan Outreach began trialling iPad interaction with the apes.
"They've been using the paint application, they love watching videos on them but they haven't really played many complex games," says Richard Zimmerman.
It is early days for the project yet but Mr Zimmerman tells BBC Nature that researchers at Toronto Zoo are now helping to quantify how the apes are interacting with the tablets.
"It's not really toy-like because they are engaging with them as devices... it's definitely going in the cognitive direction."
As a conservation charity, Mr Zimmerman says Orangutan Outreach's key concern is enrichment and helping to raise people's awareness of the animal's plight in the wild.
But by introducing devices to more research-focused centres, including Zoo Atlanta, they hope they will provide more scientific insights.
Orangutans are clearly fascinated by unfamiliar objects but does it matter that these tasks do not mirror natural challenges?
"Tasks do not need to be 'naturalistic', by resembling a tree or a fruit, to be effective," says Ms Clark.
"Research suggests that in terms of animal welfare, it's more important for tasks to be motivating and 'functional' rather than looking natural."Joystick games
We share 97% of our DNA with orangutans and 99% with chimpanzees so it is perhaps unsurprising that we have common interests.
But it is not just the great apes getting in on the interaction.
Professor John David Smith, from State University of New York at Buffalo and Michael Beran, from Georgia State University have trained macaque monkeys to use a joystick-based computer game.
To indicate whether the density of a pixel box that appeared at the top of the screen was either sparse or dense the monkeys had to simply move the cursor towards a letter S or a letter D.
"Rhesus monkeys can be trained to use joysticks to complete a variety of computer 'games' or tasks, and the animals readily and freely engage with these tasks for many hours of the day," explains Dr Beran.
"A number of studies suggest that the monkeys come to prefer having the computer apparatus available, to not having it available, even when the alternative is free food."
For Dr Beran, the computer games do not just enrich the lives of the monkeys, they can offer other important insights.
"In our lab perhaps the clearest indicator to us of impending illness or psychological distress in a monkey is a drop in his performance or in his production on his computer games," he explains.
Professor Smith adds: "In a sense, I think, the tasks are their 'Sudoku'.
"I have the impression that our tasks are appropriate and positive aspects of our animals' lives."
As advances in technology improve our lives they are also providing opportunities for us to learn more about our primate cousins, and enrich the experiences of those we study.
Ayumu the chimp features in Super Smart Animals on Wednesday 8 February, 20:00 GMT on BBC One.