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Best choice task with smartphone prices - an optimal stopping problem

Sahira van de Wouw, Ryan McKay, & Nicholas Furl


This is an adapted online version of Costa and Averbeck's (2013) best choice task. In the current version of the task, participants were told that they were buying a new smartphone. They were presented with sequences of prices for current (2018) flagship model phones by top brands (e.g. iPhone, Samsung, Huawei), on an up to 5GB plan with unlimited texts and minutes. All prices were actual prices (in GBP) of 2-year contracts offered by various UK retailers.

Participants were instructed to choose the most attractive price in the sequence, i.e. the lowest price. The phone prices were shown one by one, and participants had to decide after being shown each option whether to choose or reject that price. They were presented with 7 sequences of 12 prices each. Participants could not return to a previously rejected price, and if they had not chosen any price by the time they reached the last option in the sequence, that option became their choice by default. Rejected options were shown at the bottom of the screen.

The main goal for the participants was to earn as much money as possible. Bonus payments were awarded for each sequence as follows:

  • £0.12 if they chose the lowest price
  • £0.08 if they chose the second lowest price
  • £0.04 if they chose the third lowest price
  • £0.00 if they chose any other price

A total of 50 participants completed this experiment through Prolific.


The sequences were constructed randomly from a larger list of phone prices. The order in which the sequences were shown was randomised across participants. However, in the end, each participant saw the same 7 sequences.


All materials provided here come without warranties of any kind. They are used at your risk and we are not responsible for any conclusions that you draw from their use.


Any questions, please refer to sahira.vandewouw.2018@live.rhul.ac.uk

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Best choice task

Built with Task Builder 1

This is the best choice task (also known as optimal stopping task) where participants are shown sequences of smartphone prices.

Gorilla Open Materials Attribution-NonCommerical Research-Only

Costa, V. D., & Averbeck, B. B. (2013). Frontal–parietal and limbic-striatal activity underlies information sampling in the best choice problem. Cerebral cortex, 25(4), 972-982.

Instruction sheet

Built with Questionnaire Builder 1

This is the instruction sheet for the best choice task, as presented to the participants right before they start the first trial.

Gorilla Open Materials Attribution-NonCommerical Research-Only


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Conducted at Royal Holloway, University of London
Published on 09 December 2019
Corresponding author Sahira van de Wouw PhD Student
Royal Holloway, University of London