Crazy Fruits – Decision-Making in Unusual Situations

Last registered on June 30, 2023


Trial Information

General Information

Crazy Fruits – Decision-Making in Unusual Situations
Initial registration date
June 26, 2022

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
June 27, 2022, 4:49 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Last updated
June 30, 2023, 6:17 AM EDT

Last updated is the most recent time when changes to the trial's registration were published.


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Primary Investigator

JGU Mainz

Other Primary Investigator(s)

PI Affiliation
Institute for Employment Research

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
We use slot machine games to study economic decision-making in complex high-uncertainty environments. We investigate the role of playful-exploratory and / or belief-based approaches to the game that may lead to suboptimal strategy choices compared to a situation where decision-makers play according to the Bayesian multi-armed bandit model. We explain this by a proposed model of expected-utility-maximizing agents choosing between a rational Bayesian and a curiosity-driven perspective.
A set of treatments capture and disentangle this deliberate rationality-curiosity trade-off: By changing key game features, such as the stakes, we change the opportunity cost of non-expected-utility-maximizing behavior. By offering additional, albeit payoff-neutral, choices, we allow players to engage in non-standard behaviors while playing according to the payoff-maximizing strategy at the same time.
External Link(s)

Registration Citation

Hartinger, Katharina and Alexander Patt. 2023. "Crazy Fruits – Decision-Making in Unusual Situations." AEA RCT Registry. June 30.
Experimental Details


Treatments affect game features and the scope of in-game choices for the respective groups.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Fit of the multi-armed bandit model vs. our proposed model; player strategy (and in-game choices for T2) in relation to expected payoff, level of entropy, and special game situations (e.g., jackpot)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Beliefs about & attitudes towards the game; decision time & effort; relationship between in-game behavior and investment behavior
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We design a game that resembles a casino slot machine ("one-armed bandit" / "fruit machine"). Subjects play for a fixed number of rounds and can choose (and switch, at a cost) between games. Participation is incentivized. No deception.
Experimental Design Details
Not available
Randomization Method
Randomization done in lab by a computer
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
300 individuals
Sample size: planned number of observations
300 individuals
Sample size (or number of clusters) by treatment arms
100 T1, 100 T2, 100 control
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
Ethics Committee of the Catholic University of Eichstaett-Ingolstadt
IRB Approval Date
IRB Approval Number