Gamling, also known as gambling addiction or compulsive gambling, is the condition in which an individual engages in a habitual, uncontrollable and potentially self-destructive form of betting. It is an addictive behaviour that can cause harm to the gambler and their family, friends and work colleagues.

Gambling is a widely accepted form of entertainment that involves the wagering of something of value on an uncertain outcome. The risk of loss is usually compensated for by a prize or reward, typically cash. The stakes may be large, or small.

People have been gambling since antiquity, and in modern times the popularity of gambling has grown significantly. A 2007 survey showed that 68 per cent of respondents had gambled at least once in the past year.

There are many cognitive and social factors that contribute to problem gambling. This is why the diagnosis of gambling problems is so difficult to make, and why they often go undiagnosed.

One such factor is a distorted belief about the chance of winning. This belief is called the ‘Gambler’s Fallacy’ and is rooted in humans’ poor understanding of probability.

This is a common cognitive distortion in both occasional and problem gamblers. It occurs when a gambler thinks that the odds of winning are positive when in reality the objective expected value of the event is negative.

It is not surprising that this erroneous belief about the chance of winning leads to repeated gambling, which may increase the likelihood of financial losses and ultimately damage the gambler’s mental and physical well-being. It is also not surprising that gambling is frequently linked to other problems in people’s lives, such as depression and anxiety.

The ‘Gambler’s Fallacy’ is a key component of the cognitive account of gambling (Dickerson & O’Connor 2006). This approach argues that gambling behaviour is maintained by erroneous beliefs and distorted expectations about the true chances of winning, such that gamblers perceive the expected value of their gamble as positive when in fact the expected value is negative.

These distorted cognitions are particularly likely to develop in the context of gambling, where gamblers have access to a wealth of statistical information about the likelihood of a particular outcome occurring. In the case of a coin toss, for example, this information is available in the form of probabilities and probability statistics.

In the field of experimental psychology, there are numerous studies showing that human subjects are highly error-prone in generating and recognising random sequences (Tversky & Kahneman 1971; Wagenaar 1972). This is particularly true in terms of the perceived frequency of outcomes in a series.

As such, the presence of these erroneous beliefs is a major cause of problem gambling. It is therefore essential to understand the cognitive processes that underlie these faulty beliefs, and how they are nurtured in the course of gambling.

In this research, we used a combination of clinical interviews and telephone surveys to investigate the relationship between pathological gambling behaviour and these cognitive distortions. In addition, we conducted a number of cognitive and psychobiological tests, including the Wisconsin card sort test, the Gambler’s Fallacy think-aloud procedure and functional neuroimaging.