M.H. Broihanne, “Decision-Making: What Monkeys Teach Us About Ourselves”, Management Notebooks, 2014


Why do economic stakeholders so often act irrationally? In an attempt, among other things, to understand traders, finance professor Marie-Hélène Broihanne is studying the reactions of capuchin monkeys, chimpanzees, and orangutans.

As a child, she was bitten by a monkey during a visit to Rocamadour. But Marie-Hélène Broihanne does not hold a grudge. She now devotes much of her research to studying the decisions of non-human primates. Maybe she will never know why she was bitten. But every week she learns more and more about the ‘economic’ behaviors of monkeys: their capacity for anticipation, the notion that they can have reciprocity, their relationship with risk and with uncertainty...

It was Valérie Dufour, a specialist in evolutionary ethology, who brought her to this atypical work. “I had met a zookeeper who trained a tufted capuchin to exchange grapes for stones. This experience fascinated me, I wondered what the monkey could really understand. That's how it all began. I discovered Marie-Hélène Broihanne's skills in behavioral finance, and we started working together in 2007,” explains the young biologist.

For example, researchers are studying monkeys’ capacity for waiting. How long can they wait for a biscuit, knowing that they will be given more if they don't eat it right away? A chimpanzee can wait for about a quarter of an hour, exactly the same as five-year-old human child. A younger child won't last as long. “Setting an example for them, trying to influence them, has no effect. This corresponds to a general learning stage,” observes Marie-Hélène Broihanne.

This type of experience may seem a little strange. However, in the context of a prolonged economic crisis, following the sudden collapse of the financial markets, the study of economic behavior and particularly of decision-making mechanisms is, on the contrary, highly topical.


Decision-Making in Situations of Risk

No, stakeholders are not rational, as the theory once posited. And non-human primates can teach us a lot about the part of our behavior that comes from learning, and the part that is rooted in the evolution of species, and can therefore only be changed with difficulty.

“We use methodologies and knowledge from different disciplines, such as primate ethology, cognitive psychology and decision theory, and thus analyse choices in situations of risk, both in apes and humans, children and adults. Our first results were obtained as part of a research project specifically entitled “The biological bases of economic decisions” funded by the French National Research Agency between 2009 and 2012”, explains Marie-Hélène Broihanne.

The question of risk is at the heart of the work carried out by the two researchers. “We carry out typical experiments. We offer the monkeys a cupcake that they can choose to keep (the safe option), or exchange (the risky option) for the contents of one of the six cups that we show them, each containing different sized cakes,” explains Marie-Hélène Broihanne. Monkeys generally like to take part in these kinds of lotteries, especially the naturally playful macaques. The researchers then study their reactions, analysed in comparison to those of humans.

Loss aversion, for example, is a common feature of both. If a human loses €100, they will feel so frustrated that they will need to earn €225 to feel good again. A monkey’s perceptions are very similar.

Other behavioral biases have been identified. If they were as rational as they believe, humans would be better off, for example, selling when prices go up and buying when they go down. However, there are many who do the opposite. This is what financial researchers call the “disposition effect”.

Many also increase the stakes when they start to win, and withdraw from the game when they lose. Exactly like monkeys, and contrary to all reasonable thinking! “We call this the hot hand fallacy. We have inherited it from a long history, through the millennia,” explains Valérie Dufour. “A long time ago, our ancestors, when they found food, such as fruit or small animals, thought they had better take it all before taking the risk of going elsewhere. As long as they found it, they kept looking in the same place. It was a question of the species’ survival. Humans and monkeys have inherited this same reflex, stemming from evolution, and therefore it is quite difficult to modify. ”


Ancestral Behaviors

The work of Marie-Hélène Broihanne and Valérie Dufour mixes experimentation and statistical analysis. “I analyse the data collected in the field by Valérie, who conducts the experiments with the monkeys and records all their reactions. Once I have put this information together, I compare it with data from economic theory on human decision-making,” observed the researcher. “When these results coincide, we are confronted with behaviors that could be described as innate, unlikely to change quickly”.

Marie Hélène Broihanne and Valérie Dufour have thus shown that neither monkeys nor humans correctly assess the probability of success, even if they are informed of it beforehand. Both tend to overestimate their chances of winning.

New avenues of research are now opening up for the duo.

“The results of our initial work have attracted the interest of prestigious scientific journals, which will give us the opportunity to work on a larger scale. Beyond risk behaviour, we now want to study the behaviour of primates, both human and non-human, in situations of uncertainty”

Marie-Hélène Broihanne

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