A number of recent studies have shown there may be a strong cognitive bias in explaining persistent gambling. Theories that have been put forward include the illusion of control, "cognitive regret," biased evaluations and the "psychology of the near miss." Two exploratory studies examining the acquisition, development and maintenance of gambling behaviour involving adolescent fruit machine gamblers were carried out. Those factors which directly relate to the cognitive biases (notably erroneous beliefs about skill) during gambling activity are discussed with reference to the above cognitive influences.