Researchers believe that an area of the brain thought to be important for emotion may be hyperactive in gambling addicts. People who suffer damage to this area - the insula - do not appear to experience the distorted thinking that spurs people to keep gambling.
Dr. Luke Clark, of the University of Cambridge, and colleagues report their findings in the Proceedings of the National Academy of Sciences, PNAS.
Many of us who play the lottery or the occasional game on a slot machine or roulette wheel have felt the hope that is reflected in thoughts like - "I didn't win this time, so I am bound to win next time."
But problem gamblers seem to be more susceptible to this distorted thinking - what the researchers describe as "distorted psychological processing of random sequences (the gambler's fallacy) and unrewarded outcomes that fall close to a jackpot (near misses)."
We experience the gambler's fallacy when we toss a coin and get 10 heads in a row. There is a natural tendency to believe the odds of tossing a tails next time is higher. Yet while it feels hard to believe, the odds are exactly the same for the 11th toss, even after 10 heads in a row, as they were for the first - the chance of tossing tails is still 50-50.
The "near misses" distorted thinking is the kind that makes us believe that because we just missed the jackpot this time, it means we are more likely to hit it next time or in the future. Yet here also, in a game of pure chance, the odds of a future win are completely independent of previous wins and losses.
More and more research is showing that problem gamblers are particularly susceptible to such cognitive distortions.
For many people who participate, gambling is just a form of entertainment. But for a small minority of players - in the UK this is between 1-5%, say the researchers - the gambling becomes excessive, resulting in features characteristic of addiction, plus undesirable consequences such as financial debt and family difficulties.
Are erroneous beliefs of gambling linked to a particular brain region?
The researchers used a roulette wheel game as part of their study to investigate the "gambler's fallacy."
To investigate whether there might be a neurological explanation for the erroneous beliefs seen in problem gambling, Dr. Clark and colleagues decided to examine patients with brain injury, as he explains:
"While neuroimaging studies can tell us a great deal about the brain's response to complex events, it's only by studying patients with brain injury that we can see if a brain region is actually needed to perform a given task."
They recruited patients with injuries to one of three different parts of the brain - the insula, the amygdala or the ventromedial prefrontal cortex - and invited them to play two different gambling games: one using a slot machine and another using a roulette wheel.
The slot machine game was designed to deliver wins and near misses, such as a near jackpot where one of the cherries is just one place above or below the winning line. The roulette game just involved red or black predictions to bring out the gambler's fallacy (i.e. assuming the chances of black are higher if there has been a run of reds).
For comparison, the researchers also invited patients with injuries to other parts of the brain and healthy volunteers to play the gambling games.
The insula could be hyperactive in problem gamblers
The results showed that only participants with intact insulas showed signs of cognitive distortion. They were more motivated to continue playing after near misses (compared with after full misses) on the slot machine, and they were also more likely to choose either color less after longer runs of that color on the roulette game.
This was not the case in those participants who had suffered damage to the insula, suggesting the damage had abolished the tendency to the type of distorted thinking that problem gamblers are more prone to.
Dr. Clark says the finding leads them to believe "the insula could be hyperactive in problem gamblers, making them more susceptible to these errors of thinking."
In other words, this study seems to be saying that distorted thinking happens in a healthy, intact brain, but in problem gamblers, perhaps the distortion is more extreme, or harder to restrain, because of an overactive insula.
Dr. Clark suggests reducing hyperactivity in this part of the brain with drugs or mindfulness therapy could be a future option for treating gambling addiction.
In 2011, Dr. Clark and colleagues reported the results of another study, where they found a link between impulsivity and superstition in problem gambling. In that study, the researchers found, while observing the behavior of compulsive gamblers undergoing treatment at the National Problem Gambling Clinic, that those with high levels of impulsivity were more likely to make errors in reasoning linked to gambling.