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A Range-Normalization Model of Context-Dependent Choice: A New Model and Evidence

Soltani, Alireza and De Martino, Benedetto and Camerer, Colin (2012) A Range-Normalization Model of Context-Dependent Choice: A New Model and Evidence. PLoS Computational Biology, 8 (7). Art. No. e1002607. ISSN 1553-734X. PMCID PMC3400579. doi:10.1371/journal.pcbi.1002607.

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Most utility theories of choice assume that the introduction of an irrelevant option (called the decoy) to a choice set does not change the preference between existing options. On the contrary, a wealth of behavioral data demonstrates the dependence of preference on the decoy and on the context in which the options are presented. Nevertheless, neural mechanisms underlying context-dependent preference are poorly understood. In order to shed light on these mechanisms, we design and perform a novel experiment to measure within-subject decoy effects. We find within-subject decoy effects similar to what have been shown previously with between-subject designs. More importantly, we find that not only are the decoy effects correlated, pointing to similar underlying mechanisms, but also these effects increase with the distance of the decoy from the original options. To explain these observations, we construct a plausible neuronal model that can account for decoy effects based on the trial-by-trial adjustment of neural representations to the set of available options. This adjustment mechanism, which we call range normalization, occurs when the nervous system is required to represent different stimuli distinguishably, while being limited to using bounded neural activity. The proposed model captures our experimental observations and makes new predictions about the influence of the choice set size on the decoy effects, which are in contrast to previous models of context-dependent choice preference. Critically, unlike previous psychological models, the computational resource required by our range-normalization model does not increase exponentially as the set size increases. Our results show that context-dependent choice behavior, which is commonly perceived as an irrational response to the presence of irrelevant options, could be a natural consequence of the biophysical limits of neural representation in the brain.

Item Type:Article
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URLURL TypeDescription CentralArticle
Camerer, Colin0000-0003-4049-1871
Additional Information:© 2012 Soltani et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Received February 8, 2012; Accepted May 24, 2012; Published July 19, 2012. This study was supported by the Betty and Gordon Moore Foundation to CC, and Wellcome Fellowship to BDM. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We thank Peter Dayan and Zahra Ayubi for useful comments on the manuscript. We also thank Antonio Rangel for helpful discussions and comments on the experimental design. Author Contributions: Conceived and designed the experiments: AS BDM CC. Performed the experiments: AS BDM. Analyzed the data: AS BDM. Wrote the paper: AS
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Gordon and Betty Moore FoundationUNSPECIFIED
Issue or Number:7
PubMed Central ID:PMC3400579
Record Number:CaltechAUTHORS:20120926-094446315
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Official Citation:Soltani A, De Martino B, Camerer C (2012) A Range-Normalization Model of Context-Dependent Choice: A New Model and Evidence. PLoS Comput Biol 8(7): e1002607. doi:10.1371/journal.pcbi.1002607
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34409
Deposited On:26 Sep 2012 18:07
Last Modified:09 Nov 2021 23:08

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