Gambling Monkeys: Humans Aren't the Only Ones Who Believe in Winning Streaks

Humans are known to see winning and losing streaks in situations that are, in reality, random. Now, though, it turns out that we're not the only ones that see these "trends." Monkeys also tend to see winning streaks after a series of random events.

In order to measure whether or not monkeys could believe in winning streaks, the researchers created a computerized game for the animals. They devised a fast-paced task in which each rhesus monkey could choose either right or left and receive a reward when they guessed correctly. In all, there were three types of play; two had clear patterns (the correct answer tended to repeat on one side or to the alternate from side to side) and a third in which the lucky pick was completely random.

Where the patterns clearly existed, the monkeys quickly learned to guess the correct sequence. In the random scenarios, though, monkeys continued to make choices as if they expected a "streak." Even when rewards were random, the monkeys favored one side.

"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," said Tommy Blanchard, one of the researchers, in a news release.

The findings reveal that monkeys also share this penchant to see patterns where there are none. This suggests that it might just be an evolutionary adaptation that provided our ancestors a selective advantage when foraging for food in the wild.

"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," said Benjamin Hayden, one of the researchers. "If a belief in winning streaks is hardwired, then we may want to look for more rigorous retaining for individuals who cannot control their gambling. And investors should keep in mind that humans have an inherited bias to believe that if a stock goes up one day, it will continue to go up."

The findings reveal a little bit more not only about monkeys, but about our own biases. These findings could lend further insight into gambling addiction and show that we may be evolutionarily hardwired to believe in winning streaks.

The findings are published in the Journal of Experimental Psychology.