Puzzling Failure to Replicate the Decoy Effect: Perceptual and Context-Dependent Task
Daniela Ibarra
Department of Psychology
Faculty Supervisor: Gaurav Suri
The decoy effect occurs when adding an inferior third option shifts preferences between two choices, even though the decoy is rarely selected. This phenomenon demonstrates how decision-making can be swayed by irrelevant alternatives. Most research has focused on affect-laden contexts where strong preferences complicate isolating the effect’s mechanisms. Parrish et al. (2015) addressed this by showing the decoy effect in rhesus monkeys using a simple perceptual task—choosing rectangles with the largest area. We tested whether this effect generalizes to humans. Participants (n = 50) completed 400 perceptual trials, analyzed with within-subjects ANOVAs and paired t-tests. Contrary to expectations, we found no evidence of a decoy effect. Follow-up studies in more typical affect-driven contexts – such as scenarios involving travel destinations and beverage preferences – also failed to replicate the decoy effect.
These results raise questions about the robustness and generalizability of the decoy effect across contexts. We suggest avenues of future explorations.