The first study in non-human primates focusing on decision-making has revealed that monkeys share humans’ unfounded belief in winning and losing streaks.
To measure whether rhesus monkeys believe in winning streaks, the team created a computerised game that was so captivating monkeys would want to play for hours.
Scientists devised a fast-paced task where each monkey could choose right or left and receive a reward if they guessed correctly.
Researchers created three types of play, two with clear patterns and a third in which the lucky pick was random. Where clear patterns existed, the three monkeys in the study guessed the correct sequence.
However, in the random scenarios, the monkeys continued to make choices as if they expected a “streak”. In other words, even when rewards were random, the monkeys favoured one side.
Mr Blanchard said: “They had lots and lots of opportunities to get over this bias, to learn and change, and yet they continued to show the same tendency.
“Biases in our decision-making mechanisms, like this bias towards belief in winning and losing streaks, say something really deep about what sorts of creatures we are. We often like to think we make decisions based only on the information we’re conscious of, but we’re not always aware of why we make certain decisions or believe certain things.
“We don’t know where a lot of these biases come from, but this study – and others like it – suggest many of them are due to cognitive mechanisms we share with our primate relatives.”