The Dual Process Model (DP IB Psychology): Revision Note

The dual process model

• The DPM is a framework for explaining thinking and decision-making

• Decision-making is inseparable from thinking because choices can only be made after considering available options

• First proposed by Wason & Evans (1975), the model highlights that humans use two systems of thinking:

  • System 1 (S1) is fast, intuitive, automatic thinking

  • System 2 (S2) is slow, rational, effortful thinking

System 1 (S1) – intuitive thinking

• Operates automatically and requires little effort or time

• Relies on heuristics and biases, which can lead to errors or inaccuracies

• Not “bad” — it saves time and cognitive energy, drawing on instincts, past experiences and learning

• Especially useful in situations needing split-second responses, e.g.,

  • choosing pizza toppings

  • quickly crossing a road to avoid traffic

  • experienced drivers going into ‘automatic mode’

System 2 (S2) – rational thinking

• Operates more slowly, requiring effort and analysis

• Involves higher-order information processing and is uniquely human

• Leads to more accurate and reliable decisions

• Not always “best” — it uses significant cognitive energy, and humans are often cognitive misers, avoiding unnecessary effort, e.g.,

  • buying a house

  • preparing for a job interview

  • a learner driver focusing on each step of driving

Interaction of systems

• Both systems interact and complement one another

• At times, S2 may override S1 if careful, rational thinking is required

Research which supports the dual process model

Alter et al. (2007)

Aim:

• To investigate the dual process model via the effect of disfluency (operationalised using a difficult-to-read font) on S1 and S2 thinking

Participants:

• 40 undergraduate students from Princeton University in the USA, obtained via self-selecting (volunteer) sampling

Procedure:

• This was an independent measures design in which participants were given identical cognitive reflection tests (CRT) to answer

• The CRT comprised questions that were not inherently difficult but which required some cognitive energy to solve, such as:

  • A bat and a ball together cost $1.10. The bat costs $1 more than the ball. How much does each cost separately?'

    • The answer is that the bat costs $1.05 and the ball costs 5 cents but most people are likely to say that the bat costs $1 and the ball costs 10 cents as this is the quickest, easiest answer (even though it is incorrect)

• The participants were randomly allocated to one of two conditions:

  • Fluent condition: CRT questions in an easy-to-read font (black, 12-point)

  • Disfluent condition: CRT questions in a harder-to-read font (grey, italic, 10-point)

• It was hypothesised that the disfluent font would force participants to concentrate more, triggering System 2 thinking (slower, analytical) instead of relying on System 1 (fast, intuitive)

• The dependent variable was measured as the number of correct responses per condition

Results:

• Participants in the disfluent condition answered more CRT questions correctly than those in the fluent condition

Conclusion:

• A disfluent font increases the likelihood of System 2 processing, as it requires more cognitive effort than a fluent font

• This supports the dual process model, showing that external factors (like text fluency) can influence whether we rely on fast, intuitive thinking or slower, rational thinking

Evaluation of the dual process model

Strengths

• The model provides a compelling explanation of ‘thinking fast and slow’, which is easily applicable to a range of situations, i.e., it has good validity

• The model could be used to improve decision-making in key environments such as business, education, policy-making, etc.

Limitations

• The model is good at highlighting what may be at the root of thinking and decision-making but it is not so good at explaining how S1 and S2 work

  • This means that it lacks explanatory power

• Trying to operationalise both S1 and S2 thinking is difficult, which means that research in this field is not entirely conclusive as to which system is being used during the set tasks

Link to concepts

Measurement

• Research into the DPM is predominantly lab-based and uses artificial, contrived tasks

  • This means that it tends to be low in both mundane realism and ecological validity

• To improve this lack of validity, research on the DPM should take place in real conditions which mirror real experience

Change

• Ever-increasingly sophisticated advances in technology may change the way in which humans access and use both S1 and S2 thinking

• Some research has found that playing computer games improves teenagers' performance on computer-based educational tasks using S1 thinking

• However, there are some schools of thought which suggest that heavy use of social media can negatively impact critical thinking skills (S2)

  • This may be due to factors such as decreased attention spans, and the tendency of users to react using emotion rather than logic