winning streak
June 28, 2014

Like Humans, Monkeys Believe In Winning Streaks

Alan McStravick for - Your Universe Online

Walk across any casino floor and you will see games that, from an outsider's perspective, are clearly random. Playing your chances on which card will next be turned up, where the ball will bounce and land on a roulette wheel or how the dice will roll in a hot hand of craps are examples of placing your fate squarely in the realm of chance. Unless, of course, you are the one playing at any of these tables. There is something deeply ingrained in human behavior that unwittingly forces us to see the concept of a streak, winning or losing, in a situation that couldn't be any more random.

Until a recent study, there was disagreement in the scientific community about whether this “hot-hand bias” was a learned cultural artifact picked up in our youth or a predisposition rooted deeply in our cognitive architecture.

Tommy Blanchard, a doctoral candidate at the University of Rochester (UR) studying brain and cognitive sciences and lead author of the paper has conducted the first study in non-human primates meant to explore this systematic error in decision making. Surprisingly, it was found that monkeys share the same unfounded belief in winning and losing streaks that we humans often see. Theorizing that this is, in fact, an inherited or evolutionary adaptation, Blanchard claims this pattern-seeking may have been a key factor in providing a selective advantage to our ancestors during the act of foraging for food in the wild.

Collaborating on the study were assistant professor of brain and cognitive sciences at UR, Benjamin Hayden and Andreas Wilke, assistant professor of psychology at Clarkson University. Their findings are to be published in the forthcoming July issue of the Journal of Experimental Psychology: Animal Learning and Cognition.

The study was able to determine that rhesus monkeys have a proclivity towards believing in winning streaks. This was achieved by the creation of a computerized game that, as the researchers note, was so compelling the monkeys would want to continue playing for hours on end. “Luckily, monkeys love to gamble,” Blanchard commented. The team devised a fast-paced task in which each monkey could choose from either the left or right side. With each correct selection the monkey was presented with a reward.

Within the game were three styles of play. The first two presented clear patterns to the monkey players. The correct answer would often repeat on one side in the first game play scenario. Scenario two would see the correct answer alternate from side to side. However, the third style of game play presented no discernible pattern and was created to be completely randomized.

The three monkey participants were very quick to pick up on the patterns in the first two game play situations allowing them to quickly guess the correct sequence. However, when the game was switched to its random mode the monkeys would continue making their selections as if they expected a “streak.” Even when the rewards were random, the monkeys favored playing one side.

Over several weeks of play and 1,244 trials per game play situation, the monkeys just could not shake their hot-hand bias. “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,” Blanchard explained.

It's the steadfast belief that luck will change even when all available evidence points to the random nature of the task that led the researchers to theorize this trait has roots in our early evolutionary history. The distribution of food in the wild, which is not random at all, could well be the culprit. “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,” Hayden noted, “because beetles, like most food sources, tend to live near each other.”

When you add the fact that our brains have been trained over millennia to seek out patterns, it is not a far stretch to imagine that we would overlay that desire onto a situation that is completely random. “We have this incredible drive to see patterns in the world, and we also have this incredible drive to learn,” stated Hayden. “I think it's very related to why we like music, and why we like to do crossword puzzles, Sudoku, and things like that.” He continued, “If there's a pattern there, we're on top of it. And if there may or may not be a pattern there, that's even more interesting.”

Blanchard explains how he was drawn to the study thanks to his training in philosophy prior to his doctoral work. “Biases in our decision making mechanisms, like this bias toward believing 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.”

Results from this study could find practical application in the treatment of gambling addiction as well as provide insight for investors in the stock market. “If a belief in winning streaks is hardwired,” explained Hayden, “then we may want to look for more rigorous retraining for individuals who cannot control their gambling.” Hayden concluded, “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.”

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

Funding for this research study was provided by grants from the National Science Foundation and the Brain and Behavior Research Foundation.

Image 2 (below): Benjamin Hayden and his group study decision making in Rhesus monkeys at the University of Rochester and at a field site in Puerto Rico, where this photo was taken. Credit: Sarah Heilbronner, University of Rochester


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