Support Theory
Support theory is a framework for understanding probability judgments that emphasizes description-dependence and the balance of evidence. It applies to decision making, calibration, and phenomena like the above-average effect.
THE IDEA
Support Theory
Support theory examines how the description of an event affects its judged probability. A more detailed description may bring evidence to mind that a broad label does not, changing the apparent balance of support even when the underlying event is unchanged.
Unpacking is one application: listing several ways an event could occur may increase the support assigned to it. The framework also concerns ratings of evidence strength, calibration, and decision-making. The source proposes extending this approach to self-assessment, including judgments about being above average, but this excerpt does not supply that case study.
When to use it
Comparing risk estimates for the same outcome under broad and explicitly unpacked descriptions.
Assessing project success likelihood by breaking down into individual task risks.
Understanding jury decisions by analyzing how evidence descriptions influence perceived guilt.
Improving calibration in weather forecasting by considering multiple distinct outcome descriptions.
FROM THEORY TO EVERYDAY LIFE
In practice
Probability of cause of death
Compare an estimate for death from natural causes with estimates prompted by a list of specific natural causes. If listing the possibilities raises the total assigned probability, the description has changed the judgment. The event being evaluated should remain the same for the comparison to be meaningful.
Above-average effect in self-assessment
A person may find evidence of their own driving ability easier to recall than evidence about other drivers. Support theory offers a way to examine that imbalance; this excerpt does not establish that it explains every above-average rating.
A MOMENT TO REFLECT
Put it to work.
How does the way a hypothesis is described (e.g., specific vs. general) change your confidence in its likelihood?
Can you recall a decision where unpacking a broad category into specific possibilities altered your probability estimate?
How might support theory be used to reduce overconfidence in personal predictions?
CONTINUE THE CONVERSATION
Source texts
- Heuristics and Biases The Psychology of Intuitive Judgment (Thomas Gilovich, Dale Griffin, Daniel Kahneman)