If you’ve ever ridden a hot streak “too long” at a blackjack table or left in a huff after the dealer hit 21 three times in a row, then you are no better at gambling than a rhesus monkey.

That’s not exactly the conclusion as articulated by researchers at the University of Rochester, but rather my interpretation of their study that showed monkeys possess the same “hot hand bias” as humans when it comes to gambling. In other words, both species have trouble accepting the reality of randomness.

From a university blog post:

The new results suggest that the penchant to see patterns that actually don’t exist may be inherited—an evolutionary adaptation that may have provided our ancestors a selective advantage when foraging for food in the wild, according to lead author Tommy Blanchard, a doctoral candidate in brain and cognitive sciences at the University of Rochester. The cognitive bias may be difficult to override even in situations that are truly random. This inborn tendency to feel that we are on a roll or in a slump may help explain why gambling can be so alluring and why the stock market is so prone to wild swings, says coauthor Benjamin Hayden, assistant professor brain and cognitive sciences. “Luckily, monkeys love to gamble,” says Blanchard.

Presumably because monkeys would make a mess of playing cards, the researchers devised games that in two instances returned patterned results that were quickly learned, but in a third produced results that were truly random. The monkeys played all three scenarios the same way – even over time -- thereby exhibiting the “hot hand bias” that has been the undoing of many a human gambler.

The full report can be purchased here.

“We’re a complex mix of biases and heuristics and statistical reasoning,” says Blanchard. “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.”