Responses to Modified Monty Hall Dilemmas in Capuchin Monkeys, Rhesus Macaques, and Humans

Julia Watzek,Sarah F Brosnan,David A Washburn,Will Whitham

doi:10.46867/ijcp.2018.31.03.06

Abstract

The Monty Hall Dilemma (MHD) is a simple probability puzzle famous for its counterintuitive solution. Participants initially choose among three doors, one of which conceals a prize. A different door is opened and shown not to contain the prize. Participants are then asked whether they would like to stay with their original choice or switch to the other remaining door. Although switching doubles the chances of winning, people overwhelmingly choose to stay with their original choice. To assess how experience and the chance of winning affect decisions in the MHD, we used a comparative approach to test 264 college students, 24 capuchin monkeys, and 7 rhesus macaques on a nonverbal, computerized version of the game. Participants repeatedly experienced the outcome of their choices and we varied the chance of winning by changing the number of doors (three or eight). All species quickly and consistently switched doors, especially in the eight-door condition. After the computer task, we presented humans with the classic text version of the MHD to test whether they would generalize the successful switch strategy from the computer task. Instead, participants showed their characteristic tendency to stick with their pick, regardless of the number of doors. This disconnect between strategies in the classic version and a repeated nonverbal task with the same underlying probabilities may arise because they evoke different decision-making processes, such as explicit reasoning versus implicit learning.

Highlights

The Monty Hall Dilemma (MHD) is a simple probability puzzle famous for its counterintuitive solution
Participants switched less in the threedoor condition than in the eight-door condition, t(75.47) = -3.01, p = 0.004), and humans switched more than capuchin monkeys, t(106.92) = -6.27, p < 0.001, and showed a nonsignificant trend toward switching more than rhesus macaques, t(92.46) = -2.17, p = 0.082
Switch responses were significantly lower in the three-door condition when it was presented before the eight-door condition than when it was presented after the eight-door condition, (Figure 3, left panel, t(40.04) = -5.70, p < 0.001)

Summary

Introduction

The Monty Hall Dilemma (MHD) is a simple probability puzzle famous for its counterintuitive solution. We presented humans with the classic text version of the MHD to test whether they would generalize the successful switch strategy from the computer task Instead, participants showed their characteristic tendency to stick with their pick, regardless of the number of doors. When, in addition to switching and staying, participants were given the option to indicate whether they thought that the chances that the reward was behind the two remaining doors were equal, 86% indicated this belief (De Neys & Verschueren, 2006) This would only be true if the car were randomly placed behind the two remaining doors. Sticking with the initial choice wins in one out of the three scenarios (1/3) and switching wins in two out of the three scenarios (2/3)

Objectives

Methods

Results

Discussion

Conclusion