Clarifying the role of an unavailable distractor in human multiattribute choice

Abstract
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Abstract

Decisions between two economic goods can be swayed by a third unavailable 'decoy' alternative, which does not compete for choice, notoriously violating the principles of rational choice theory. Although decoy effects typically depend on the decoy's position in a multiattribute choice space, recent studies using risky prospects (i.e., varying in reward and probability) reported a novel 'positive' decoy effect operating on a single 'value' dimension: the higher the 'expected value' of an unavailable (distractor) prospect was, the easier the discrimination between two available target prospects became, especially when their expected-value difference was small. Here we show that this unidimensional distractor effect affords alternative interpretations: it occurred because the distractor's expected value covaried positively with the subjective utility difference between the two targets. Looking beyond this covariation, we report a modest 'negative' distractor effect operating on subjective utility, as well as classic multiattribute decoy effects. A normatively meaningful model (selective integration), in which subjective utilities are shaped by 'intra-attribute' information distortion, reproduces the multiattribute decoy effects, and as an epiphenomenon, the negative unidimensional distractor effect. These findings clarify the modulatory role of an unavailable distracting option, shedding fresh light on the mechanisms that govern multiattribute decisions.

Data availability

The current manuscript re-analyses previously published datasets, so no new data have been generated for this manuscript. Analysis/computational modelling code has been uploaded to GitHub: https://github.com/YinanCao/multiattribute-distractor/

The following previously published data sets were used

1. Chau B
2. Kolling N
3. Hunt L
4. Walton M
5. Rushworth M
(2020) Data from: A neural mechanism underlying failure of optimal choice with multiple alternatives
Dryad Digital Repository, doi:10.5061/dryad.040h9t7.

https://doi.org/10.5061/dryad.040h9t7
(2018) Data from: Value-based attentional capture affects multi-alternative decision making
The Open Science Framework (OSF): https://osf.io/8r4fh/.

https://osf.io/8r4fh/

Article and author information

Author details

Yinan Cao

Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany

For correspondence
ycaoneuro@gmail.com

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-9881-5106
Konstantinos Tsetsos

School of Psychological Science, University of Bristol, Bristol, United Kingdom

For correspondence
k.tsetsos62@gmail.com

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-2709-7634

Funding

European Research Council (EU Horizon 2020 Research and Innovation Program (ERC starting grant no. 802905))

Konstantinos Tsetsos

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: The current manuscript re-analyses previously published datasets, thus no data have been generated for this manuscript. The relevant information about ethical approvals of these published datasets can be found in the original studies.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.