These monkeys can barter, but can they gamble? Alberta prof hopes to find out

An Alberta psychology professor and team are heading to Bali to find out whether a unique population of long-tailed macaque monkeys can gamble as well as they can barter.

University of Lethbridge professor Jean-Baptiste Leca has been studying the macaques of Bali for years now, and found that they have a developed a cultural practice of stealing from humans and then bartering for food.

They seem to understand that some items — cellphones, sunglasses, wallets — are more prized by the humans, and are easier to steal than actual food.

"It's a fairly well-established and unique bartering system in which the monkeys have learned that they have some control of the situation in the exchange of objects for food," Leca told The Homestretch Wednesday.

The monkeys seem to learn the behaviours, he said, and some personalities are better at it than others; it requires boldness, patience and self-control to hold out for a better food item.

The bartering process can take several minutes, and the most highly prized food item seems to be a raw egg.

• Watch bartering monkeys in Bali in this video shot by Jean-Baptiste Leca:

Leca wants to take the bartering research one step further with a new study, asking whether these monkeys can gamble.

"They might have a simple rule in mind whereby, if they stole a highly valued object, they know they can either get more food or better food than if they stole a lesser valued object," he said.

"Now we wondered what the monkeys would do if we changed the rules a little bit and introduced some levels of uncertainty in the food that they receive." 

Can monkeys be problem gamblers?

Leca compared his idea to a slot machine that returns two lemons, which, for most humans, would be an incentive to keep playing for more.

"The idea would be to see whether these monkeys, who have some knowledge of exchanges and a currency system, whether they would be prone to the kind of cognitive biases that we know exist in human gamblers," says Leca, whose group is supported by a research grant from the Alberta Gambling Research Institute.

A cognitive bias is the same thing that makes you believe that you'll win on the next pull, or that if you've seen red come up six times in roulette, that a black is more likely to be next. In reality, the chance is random.

"It's a systematic error in thinking that people tend to make," he said.

Leca may be able to confirm that monkeys in the wild show the same cognitive bias as human problem gamblers.

"It will tell us that there are some common evolutionary origins in the kind of cognitive biases that problem gamblers experience," he said.

Even though there are populations of long-tailed macaque monkeys all around Bali, the behaviour seems to only take place on the southern tip of the island. The monkey act this way in places such as the popular Uluwatu Temple, which suggests it is a learned, cultural behaviour.

This is Leca's area of study. As an associate psychology professor, he focuses on behavioural innovations in non-human primates.

He's working with others from the University of Lethbridge including his wife, Noëlle Gunst, an adjunct faculty and research associate in the university's psychology department; gambling research expert Rob Williams; and students Matthew Gardiner, Caleb Bunselmeyer and Christian Dunn.

They're also working with Elsa Addessi, a cognitive psychologist and primatologist at the National Research Center in Rome and I. Nengah Wandia, a veterinarian and primatologist at Udayana University in Bali.

A few years ago, Leca discovered that adolescent female macaques were humping the backs of deer in Japan. The story made it onto the Top 10 weirdest As It Happens stories of all time.

Leca said he's looking forward to this monkey gambling study because most studies are typically conducted on captive, lab-trained and socially isolated primates.

"So to our knowledge, it's the first time that this kind of experimental gambling research will be conducted on free-ranging non-human animals," he said. "Basically we'll have an outdoor lab."

The team has devised a number of gambling tasks for the macaques. One of them is a modified version of the slot machine. Leca wants to see if the monkeys will respond to the "near miss" effect the same way humans do.