Balance between breadth and depth in human many-alternative decisions

  1. Alice Vidal  Is a corresponding author
  2. Salvador Soto-Faraco
  3. Ruben Moreno Bote
  1. Universitat Pompeu Fabra, Spain


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 here

The following data sets were generated

Article and author information

Author details

  1. Alice Vidal

    Universitat Pompeu Fabra, Barcelona, Spain
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-4477-510X
  2. Salvador Soto-Faraco

    Universitat Pompeu Fabra, Barcelona, Spain
    Competing interests
    The authors declare that no competing interests exist.
  3. Ruben Moreno Bote

    Universitat Pompeu Fabra, Barcelona, Spain
    Competing interests
    The authors declare that no competing interests exist.


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.

Reviewing Editor

  1. Valentin Wyart, École normale supérieure, PSL University, INSERM, France


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.

Version history

  1. Preprint posted: November 10, 2021 (view preprint)
  2. Received: January 11, 2022
  3. Accepted: September 12, 2022
  4. Accepted Manuscript published: September 15, 2022 (version 1)
  5. Version of Record published: October 17, 2022 (version 2)


© 2022, Vidal et al.

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.


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  1. Alice Vidal
  2. Salvador Soto-Faraco
  3. Ruben Moreno Bote
Balance between breadth and depth in human many-alternative decisions
eLife 11:e76985.

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