Humans tend to “see” patterns in winning and losing streaks in situations which are actually random. A new study has shown that this “hot hand bias”also occurs in non-human monkeys.

Rhesus monkeys also believe in winning streaks – even when it isn’t the case.

“Human decision-makers often exhibit the hot-hand phenomenon, a tendency to perceive positive serial autocorrelations in independent sequential events. The term is named after the observation that basketball fans and players tend to perceive streaks of high accuracy shooting when they are demonstrably absent.”

Researchers don’t currently agree whether this bias is something limited to humans or not, but reporting the phenomenon in non-human monkeys, as opposed to say chimps, is a strong indication that our many exhibit this behavior as well.

“We hypothesize that this bias reflects a strong and stable tendency among primates (including humans) to perceive positive autocorrelations in temporal sequences, that this bias is an adaptation to clumpy foraging environments, and that it may even be ecologically rational”, say the authors of the study: Benjamin  Hayden, Tommy Blanchard, and Andreas Wilke.

[Also read: How scientists taught monkeys the concept of money. Not long after, the first prostitute monkey appeared]

Flip a coin. What side will it land on ?

Luckily for the researchers, monkeys love to gamble – just like humans, one might argue. So they devised a quick-thinking task in which each rhesus monkey could choose right or left and receive a reward when they guessed correctly. For the purpose of the experiment, they created three types of play: two with clear patterns, and one which was fully random.

Where the clear patterns existed, the rhesus monkeys quickly found them and started to guess the correct sequence. But in the random scenario, the monkeys acted as if they expected a “streak.” In other words, even when the reward was entirely random, they still acted like one option was more likely. Let me paint this another way: if you have to choose between two cards, one red and one black, and 4 times in a row, the red card is the winner, which is more likely to be the winner the next time? The answer is: they’re both just as likely. In a strictly random scenario, even if one of two options is the winner 100 times in a row, the 101th will still be 50-50 (though the odds for that are astronomical).

The monkeys were subjected to an average of 1244 trials, so they had a lot of chances to get rid of the hot hand bias, but just like humans, they showed no signs of giving it up. Scientists believe this happens because the distribution of food in nature is not random.

“If you find a nice juicy beetle on the underside of a log, this is pretty good evidence that there might be a beetle in a similar location nearby, because beetles, like most food sources, tend to live near each other,” explains Hayden.

Individuals who were more likely to spot out these patterns were more likely to thrive and pass the genes on to their offspring – and thus evolution makes us acquire a new treat; one which makes us better at finding food in the wild, but makes us worse at playing the roulette. The results could have major implications in areas from investing to the study of human free will.

“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.”

All in all, we’re complex – nature shaped us that way.

“We’re a complex mix of biases and heuristics and statistical reasoning. When you put it all together, that’s how you get sophisticated behavior. 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,” says Blanchard.

You can read the full study for free here.