Reading focus
Syllabus: How Do We Judge and Decide?
Connect the paired choice patterns to editing, reference points, value, and decision weights. Keep the original formulation's assumptions visible.
Why you're reading it. Evaluate a descriptive model that explains several contrasts with an explicit structure.
A question to consider. Two people have the same estimate of an outcome's probability but make different choices. Which parts of the model could account for this, and what would you measure to distinguish them?
Why this reading
A theory of choice must explain how outcomes and probabilities combine, not merely note that people sometimes avoid risk. Kahneman and Tversky use patterned choices to challenge a descriptive model and construct an alternative. The paper makes the relationship between observation and formal explanation unusually explicit.
Before you read
Expected value averages monetary outcomes using their probabilities. Expected utility averages their subjective utilities. A reference point separates gains from losses. Diminishing sensitivity means that equal changes can matter less farther from that point. Decision weights describe an outcome's influence on choice; they are not simply a person's stated probability estimates.
Read for
- Work through paired choice problems and identify which assumption each contrast challenges. Keep certainty, gains versus losses, and problem editing distinct.
- Connect the value and weighting functions to the patterns they are meant to explain. Identify what is assumed about the reference point.
- Examine the reliance on hypothetical choices, the samples, and the limits of the proposed formulation. Distinguish a descriptive model from advice about what someone ought to choose.
Consider afterwards
- Two people face identical final outcomes but regard different amounts as their starting point. Construct a choice example in which a reference-dependent account and an account based only on final wealth could make different predictions.
Editorial context
This is the original 1979 formulation, not every later version of prospect theory. Loss aversion, diminishing sensitivity, and probability weighting make different claims and should not be collapsed into a universal rule that losses count twice as much. Ruggeri and colleagues' multinational replication reproduced many original choice patterns, with attenuation and variation. Replicating those patterns does not uniquely establish the mechanism or settle every criticism of the theory.