During a famous roulette game in a Monte Carlo casino in 1913, black came up 26 times in a row. After about 15 repetitions, the players began betting heavily on red, likely believing that such a long streak just couldn鈥檛 continue.
The gambler鈥檚 fallacy鈥攖he idea that past events, a streak of black in roulette, for example, can impact the likelihood of a future random event, whether black or red will come up after the next spin鈥攈as long been thought to illustrate human irrationality.
But new research that relies on a brain model created at the University of Colorado Boulder finds that when humans fall into the gambler鈥檚 fallacy, their brains may actually be acting with some logic after all.
The new study, published today in the Proceedings of the National Academy of Sciences, finds that the human brain may in fact be sensitive to a subtle pattern that shows up in otherwise random sequences鈥攁 pattern that may not be obvious to our conscious minds.
鈥淥ur brains are constantly soaking up all kinds of things that we don鈥檛 even know about鈥攖hat are little irregularities in the world,鈥� said Randall O鈥橰eilly, a professor of psychology and neuroscience at CU-Boulder and a co-author of the paper. 鈥淣obody, if you ask them, would tell you this structure is there, but your brain knows.鈥�
The structure that exists in a chain of random events鈥攍ike tossing a 鈥渇air coin鈥� over and over鈥攈as to do with whether the sequence alternates (heads-tails or tails-heads, for example) or repeats (heads-heads or tails-tails, for example.) A fair coin is any coin that鈥檚 as likely to come up heads as tails in any given toss.
While each individual toss has a 50 percent chance of coming up heads or tails, statisticians have found that over time the sequence of heads and tails has a subtle pattern to it: Repetitions tend to bunch together with greater spacing between them.
For the study, the research team, led by Texas A&M Health Science Center, used CU-Boulder鈥檚 computer model of neurons to see if the brain could pick up the subtle pattern. They found that over time, the brain did indeed pick up the structure in the sequence, learning that series of alternations tend to go on for longer periods of time than series of repetitions.
鈥淚n other words, these neurons behaved just like the gamblers in a casino: When the outcome of a fair coin toss is a head, they are more likely to predict that the following toss will be a tail than to predict it will be a head, despite the fact that either pattern is equally probable,鈥� said Yanlong Sun, an assistant professor at Texas A&M and lead author of the paper.
The research was partially funded by the Air Force Office of Scientific Research, the Office of Naval Research, and Intelligence Advanced Research Projects Activity.
Other co-authors of the paper are Jack Smith and Hongbin Wang, of Texas A&M; Rajan Bhattacharyya, of HRL Laboratories LLC; and Xun Liu, of the Chinese Academy of Sciences.
