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Incorrect claims gambling is caused by brain damage
They compared these with 16 healthy people, and 13 people with brain injuries that did not affect those specific regions.
Participants were given a computer slot machine and roulette games.
The slot machine game was programmed to deliver near-misses, as well as wins and full-misses. Half the time participants were asked to select a play icon from one of six alternatives, the rest of the time the computer selected a play icon. After the play icon was selected, participants were asked to rate their chances of winning. The participants then received a win or no-win result. After each play, participants were asked how pleased they were with the result and how much they wanted to continue playing the game.
Participants played 90 times on the roulette wheel game. The roulette wheel displayed an equal number of red and blue segments, and before each game the participant had to choose a colour. This game assessed gambler's fallacy. The gambler's fallacy is a bias in the processing of randomness, whereby recent consecutive outcomes are considered less likely to repeat, and conversely, outcomes that have not occurred in the recent history are perceived as "due". The researchers looked to see whether participants chose a colour (red/blue) after runs of that colour outcome.
What were the basic results?
Slot machine game
When participants selected the play icon for themselves, rather than the computer selecting it for them, they rated their chances of winning as higher. The researchers suggest that this is consistent with the illusion of control that leads from personal choice. There was no difference between people with injuries in specific target regions, healthy people and people with other brain injuries.
Participants were happiest with the result when they received a win, although response to a win was significantly reduced in people with injuries in specific target regions compared to people with other brain injuries. How pleased participants were with winning was not affected by whether they or the computer had selected the play icon.
Receiving a win increased motivation to continue. There was no difference between people with injuries in specific target regions, healthy people and people with other brain injuries, and motivation was not significantly affected by whether they or the computer had selected the play icon.
Compared with full misses, near misses also increased motivation to continue playing. However, people with brain injuries in specific target regions had reduced motivation to continue playing following near misses versus "full misses" compared to healthy participants and participants with other brain injuries.
When the people with injuries in specific target regions were divided up, it was found that people with injuries in the insula had reduced motivation to play following a near miss than following a full miss. People with injuries in the vmPFC also had reduced motivation to play following a near miss than following a full miss, but the difference was smaller.
Roulette wheel game
In the roulette wheel game, participants chose each colour less after longer runs of the colour. This effect did not vary between groups.
However, when the people with injuries in specific target regions were divided up, it was found that people with injuries in the insula were more likely to choose a colour after longer runs of the same colour. This was different to people with injuries to the vmPFC and amygdala.
How did the researchers interpret the results?
The researchers conclude that, "our findings indicate that the distorted cognitive processing of near-miss outcomes and event sequences may be ordinarily supported by the recruitment of the insula. Interventions to reduce insula reactivity could show promise in the treatment of disordered gambling."
This experimental study in a small number of people with different brain injuries and a comparison group of healthy people, has found that people with brain damage to the insula (a region of the brain believed to be involved in feelings and emotional responses) had reduced motivation to play the slot machine task following near misses compared with full misses. These people also did not display classic gambler's fallacy effect on a roulette wheel game - in that they were not more likely to choose a blue after long runs of red or vice versa.
A study such as this suggests regions of the brain that may be involved in responses to gambling. However, it does not provide proof that any particular part of the brain causes gambling addiction. The study has involved only a small number of people, and comparing game performance in people with and without brain injuries does not reflect the real life scenario of gambling by people with gambling addiction.
This study could be followed up by carrying out brain imaging on people with known gambling problems to see which parts of their brain were active.
Overall, the results of this small study suggest that the insula region of the brain may play a role in responses to gambling, as well as playing a role in how we make decisions in different settings, but much further research is required.
"The gambler's fallacy explained? Misguided belief in the big win just around the corner could be down to brain damage," The Independent incorrectly reported. The news is based on a small experimental study...
Links to Headlines
The gambler's fallacy explained? Misguided belief in the big win just around the corner could be down to brain damage. The Independent, April 7 2014
Links to Science
Clark L, et al. Damage to insula abolishes cognitive distortions during simulated gambling. PNAS. Published online April 7 2014
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