18.1.9

Griffiths on Cognitive Bias

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Griffiths (1994): Cognitive Biases Using Fruit Machines

Griffiths recorded the verbalisations of 30 gamblers and 30 non-gamblers as they played on fruit machines. He concluded that gamblers were more likely to have cognitive biases, specifically the illusion of control.

Method

Method

  • The field study compared 30 gamblers to 30 people who played fruit machines occasionally.
  • Each of the players was given £3, the equivalent of 30 gambles on a fruit machine.
  • The players were told to think aloud during their play and to get to 60 gambles.
Method cont.

Method cont.

  • If they reached 60, they had a choice to keep playing or take any winnings they had received.
  • Griffiths recorded:
    • The number of gambles.
    • The players’ verbalisations of their thoughts.
    • The number of wins.
    • The outcome of each specific gamble.
Results

Results

  • Initially, some of the regular gamblers refused to play on the specific fruit machine the researchers assigned them.
  • Regular gamblers were more likely than the occasional players to play to 60 gambles.
  • The regular gamblers also were more likely to play until they had lost all of their money.
Results cont.

Results cont.

  • The regular gamblers had more irrational verbalisations, such as talking to the machine.
    • E.g. This machine doesn't like me.
  • They also referred to lost gambles as ‘near misses’ or ‘near wins’.
  • Finally, in a post-gamble interview, the gamblers believed themselves to be more skilful than the occasional players.

Griffiths (1994): Cognitive Biases Using Fruit Machines

Griffiths recorded the verbalisations of 30 gamblers and 30 non-gamblers as they played on fruit machines. He concluded that gamblers were more likely to have cognitive biases, specifically illusion of control.

Conclusions

Conclusions

  • Gamblers are more likely to demonstrate cognitive distortions. - Specifically, they are likely to show illusion of control, where they believe themselves to be more skilful than the occasional gamblers.
    • Note that the fruit machines are a game of chance where there is no skill involved.
Conclusions cont.

Conclusions cont.

  • Additionally, they believed if they were familiar with the specific machine, they were more likely to win. This is why some refused to play on their designated machine at first.
  • Finally, they also showed distorted views of reality by personifying and talking to the machines.
Evaluation

Evaluation

  • This was a field study, which means it was done on location in a casino. So this shows high ecological validity.
  • But in field studies, it is difficult to control for extraneous variables.
    • An example of an extraneous variable could have been the effect of other people/gamblers nearby.
Generalisability

Generalisability

  • The sample was also not representative of the whole population because only one female gambler participated, so the results should not be generalised to the entire population.
Validity

Validity

  • Lastly, the study was trying to record cognitive distortions, which take place internally.
  • But the participants were asked to verbalise them, which may have altered their thinking.
  • So the study’s results may be invalid.
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