Comparison-induced decoy effects

Area of Science:

• Cognitive Psychology
• Decision Making
• Social Psychology

Background:

• Decoy effects, where the presence of a third, less attractive option influences choice between two alternatives, are well-documented.
• Existing theories struggle to fully explain these effects, particularly in one-dimensional evaluations.

Purpose of the Study:

• To assess the explanatory power of existing theories regarding decoy effects in one-dimensional attribute value evaluations.
• To propose and test a novel theory, comparison-induced distortion theory, against established models.

Main Methods:

• Evaluated several prominent theories: range-frequency theory, distance-density model, diagnosticity principle, and reference point theories.
• Tested adaptation-level theory and the newly proposed comparison-induced distortion theory against a one-dimensional analogue of the asymmetric dominance effect.

Main Results:

• Parducci's range-frequency theory, Krumhansl's distance-density model, Tversky's diagnosticity principle, and reference point theories failed to account for the observed effect.
• Helson's adaptation-level theory and the comparison-induced distortion theory qualitatively explained the effect.
• Quantitative analysis indicated that comparison-induced distortion theory provided a superior fit compared to adaptation-level theory.

Conclusions:

• Established theories are insufficient to explain one-dimensional decoy effects.
• Comparison-induced distortion theory offers a more robust explanation for how decoys influence evaluations.
• Language-based magnitude comparison biases may play a significant role in mediating decoy effects on evaluations.