Tversky and Kahneman (1974) 


• Aim: 

  To demonstrate the effect of anchoring bias on numerical estimations.
• Participants: 

  High school students
• Procedure:

  1. Two conditions: ascending and descending
  2. Ascending group: Estimate 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 in 5 seconds
  3. Descending group: Estimate 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 in 5 seconds
• Results:

  • Ascending group median: 512
  • Descending group median: 2250
  • Actual value: 40320
• Conclusion: 

  The first number seen (anchor) biased the estimates, with the descending group giving higher estimates than the ascending group.
• Strengths:

  1. Simplicity and replicability: Easy to replicate, enhancing reliability.
  2. Internal validity: High control allows for causal inferences about anchoring effects.
  3. Use of median: Reduces the impact of outliers on results.
  4. Demonstrates clear effect: Shows a strong anchoring effect with a simple manipulation.
• Limitations:

  1. Ecological validity: Artificial task may not reflect real-world decision-making.
  2. Time constraint: 5-second limit may not reflect typical decision-making conditions.
  3. Sample: Use of high school students limits generalizability.
  4. Independent samples design: Participant variability could influence results.
  5. Limited scope: Focuses on one specific type of anchoring (numerical).