Irrational decisions: attending to numbers rather than ratios

When judging the probability of a low probability event, many people judge it as less likely when it is expressed as a ratio of small numbers (e.g. 1:10) than of large numbers (e.g. 10:100). This is known as the ratio-bias (RB) phenomenon. Besides confirming the phenomenon, in this experiment partic...

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Bibliographic Details
Published in:Personality and individual differences 2003-11, Vol.35 (7), p.1537-1547
Main Authors: Alonso, Diego, Fernández-Berrocal, Pablo
Format: Article
Language:English
Subjects:
Cognitive-experiential self-theory
Cognitive-Experiential selftheory
Decision making
Experiential system
Irrational decisions
Irrationality
Need for cognition
Probabilistic judgement
Probability judgments
Ratio bias
Ratio-bias phenomenom
Rational system
Reasoning
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Summary:When judging the probability of a low probability event, many people judge it as less likely when it is expressed as a ratio of small numbers (e.g. 1:10) than of large numbers (e.g. 10:100). This is known as the ratio-bias (RB) phenomenon. Besides confirming the phenomenon, in this experiment participants made irrational decisions selecting probabilities of 10% in preference to 20 and 30%, in spite of the great discrepancy of probabilities between options (greater than in previous studies). These results support an interpretation in terms of the principles of cognitive-experiential self-theory (CEST). Relation between tendency to present the RB phenomenon and degree of rationality (as measured by the Need for Cognition Scale) was also examined. Scores in rationality obtained by participants who chose the nonoptimal response were lower than scores of participants who chose the optimal response.
ISSN:0191-8869
1873-3549
DOI:10.1016/S0191-8869(02)00368-9