Related Experiment Videos
Likelihood judgment based on previously observed outcomes: the alternative-outcomes effect in a learning paradigm
Paul D Windschitl1, Michael E Young, Mary E Jenson
1Department of Psychology, University of Iowa, Iowa City 52242, USA. paul-windschitl@uiowa.edu
Memory & Cognition
|June 14, 2002
Summary
People`s certainty about an outcome is swayed by how evidence for other possibilities is presented, not just objective facts. This study shows how alternative outcome evidence impacts subjective probability and intuitive certainty.
Area of Science:
- Cognitive Psychology
- Decision Science
- Behavioral Economics
Background:
- Intuitive judgments of certainty can be influenced by factors unrelated to objective probabilities.
- The distribution of evidence for alternative outcomes can affect perceptions of a focal outcome's likelihood.
Purpose of the Study:
- To investigate the alternative-outcomes effect in a learning paradigm.
- To examine how memory for past observations influences likelihood judgments.
- To test the heuristic comparison account of judgment biases.
Main Methods:
- Participants made likelihood judgments based on learned frequencies of outcomes.
- Experiment 1 manipulated evidence distribution across alternative outcomes.
- Experiment 2 controlled for potential information loss effects on frequency estimation.
Main Results:
- Evidence distribution for alternative outcomes significantly influenced intuitive certainty estimates.
- Subjective probability judgments were also affected by the manipulation of alternative evidence.
- Findings supported the heuristic comparison account.
Conclusions:
- Judged likelihood is disproportionately influenced by the frequency of the strongest alternative outcome.
- Cognitive heuristics play a significant role in subjective probability assessments.
- Understanding these biases is crucial for accurate decision-making.