Balance between breadth and depth in human many-alternative decisions

Abstract
Data availability
Article and author information
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Abstract

Many everyday life decisions require allocating finite resources, such as attention or time, to examine multiple available options, like choosing an online food supplier. In these cases, our search resources can be spread across many options (breadth) or focused on a few of them (depth). Whilst theoretical work has described how finite resources should be allocated to maximise utility in these problems, evidence about how humans balance breadth and depth is lacking. We introduce a novel experimental paradigm where humans make a many-alternative decision under finite resources. In an imaginary scenario, participants allocate a finite budget to sample amongst multiple apricot suppliers in order to estimate the quality of their fruits, and ultimately choose the best one. We found that at low budget capacity participants sample as many suppliers as possible, and thus prefer breadth, whereas at high capacities participants sample just a few chosen alternatives in depth, and intentionally ignore the rest. The number of alternatives sampled increases with capacity following a power law with an exponent close to 0.75. In richer environments, where good outcomes are more likely, humans further favour depth. Participants deviate from optimality and tend to allocate capacity amongst the selected alternatives more homogeneously than it would be optimal, but the impact on the outcome is small. Overall, our results undercover a rich phenomenology of close-to-optimal behaviour and biases in complex choices.

Data availability

The data and analysis scripts have been deposited in an OSF repository available herehttps://osf.io/kdbqs/?view_only=386d3bde49394e6bb88d247adc52b9ad

The following data sets were generated

(2021) Humans balance breadth and depth: Near-optimal performance in many-alternative decision making
OSF, kdbqs.

https://osf.io/kdbqs/?view_only=386d3bde49394e6bb88d247adc52b9ad

Article and author information

Author details

Alice Vidal

Universitat Pompeu Fabra, Barcelona, Spain

For correspondence
alice.vidal@upf.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-4477-510X
Salvador Soto-Faraco

Universitat Pompeu Fabra, Barcelona, Spain

Competing interests
The authors declare that no competing interests exist.
Ruben Moreno Bote

Universitat Pompeu Fabra, Barcelona, Spain

Competing interests
The authors declare that no competing interests exist.

Funding

Howard Hughes Medical Institute (55008742)

Ruben Moreno Bote

Institució Catalana de Recerca i Estudis Avançats (2016)

Ruben Moreno Bote

Ministerio de Ciencia e Innovación (PID2019-108531GB-I00 AEI/FEDER)

Salvador Soto-Faraco

European Regional Development Fund (Operative Programme for Catalunya 2014-2020)

Salvador Soto-Faraco

Agència de Gestió d'Ajuts Universitaris i de Recerca (2019FI_B 00302)

Alice Vidal

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

Ethics

Human subjects: Before starting the experiment, participants had to give their informed consent. This study was part of the project 'IMC: INTEGRACIÓN MULTISENSORIAL Y CONFLICTO' (PID2019-108531GB-I00) for which an ethical approval was obtained.

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.