(Mis)anticipated Discrimination Lab Experiment

Last registered on November 18, 2025

Pre-Trial

Trial Information

General Information

Title
(Mis)anticipated Discrimination Lab Experiment
RCT ID
AEARCTR-0017144
Initial registration date
November 14, 2025

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
November 17, 2025, 2:37 PM EST

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

Last updated
November 18, 2025, 3:37 AM EST

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

Locations

Primary Investigator

Affiliation
Norwegian School of Economics

Other Primary Investigator(s)

Additional Trial Information

Status
In development
Start date
2025-11-17
End date
2025-11-20
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
The abstract is included in the uploaded pre-analysis plan document. It is not included here to prevent participants from obtaining information regarding the experiment features and treatments.
External Link(s)

Registration Citation

Citation
O'Leary, Ethan. 2025. "(Mis)anticipated Discrimination Lab Experiment ." AEA RCT Registry. November 18. https://doi.org/10.1257/rct.17144-1.1
Experimental Details

Interventions

Intervention(s)
Intervention (Hidden)
I must pre-register two important parameterisations of the experiment. First, the true value of p, the probability that robot A is used, is 0.01 or 1%. Prior to running the first session, I drew 24 random integers between 1 and 100. I specified that if any of these integers were 1, then I would have to run the corresponding number of sessions where the true robot in use was A. All the drawn integers were above 1 so all sessions therefore run with robot B making hiring decisions.

Second, the initial belief of robot B regarding who applies is crucial to the path that societies are set on. The non-discriminatory equilibrium of the model, given other parameters is that participants should apply if their productivity value is no greater than 38.5. In the discriminatory equilibrium, green participants apply if and only if their productivity value is 1 or less while purple participants apply if and only if their productivity value is 58 or less. I set the prior belief of robot B to then be the midpoint along the satiation curve between these two equilibria. This is that the prior belief of maximum productivity value of green applicants is 19.75 and that of purple applicants is 51.5. Simulation data suggested that to achieve sufficient convergence to either of the possible equilibria strategies while permitting a degree of learning the task before equilibria are reached, I should set the standard deviation of this prior to be 15.
Intervention Start Date
2025-11-17
Intervention End Date
2025-11-20

Primary Outcomes

Primary Outcomes (end points)
Belief of robot A being in use, application rate as a proxy for continuation of discrimination, bid for one round of quota policy and self-reported fairness perceptions.
Primary Outcomes (explanation)
These are all directly measured in the experiment.

Secondary Outcomes

Secondary Outcomes (end points)
Hiring rates of each group, justification of belief of robot in use, endline measure of fairness perception and belief of quota affecting hiring outcomes and application decisions and emotional status.
Secondary Outcomes (explanation)
Justification beliefs are passed through GPT to catageorise statements to one of the following: (i) use of statistical/probabilistic thinking, (ii) randomisation and/or uncertainty, (iii) following a hunch/intuition, and (iv) hopeful or forward looking. Non-categorised justifications may be manually screened and/or reclassified to a new category. These categories are based off an online pilot. Emotional state is constructed off multiple elicitations of current emotional state corresponding to upset, calmness, boredom, motivation, happiness, anxiety, tiredness, discouragement and annoyance.

Experimental Design

Experimental Design
The experiment will run at the CeDEx facility in the University of Nottingham. Across the span of one week (17th November 2025 to 20th November 2025), I will run 12 experimental sessions. In each session, I will run a maximum of 2 treatments. Participants are randomly assigned to one of two societies in each session which indicate the group of participants in the session who will interact and the treatment assignment. Each treatment will be run over 8 societies and each society will consist of 16 participants.
Experimental Design Details
I will recruit groups of 16 participants to form societies who were initially randomly divided into two group-identities defined by their colour: green and purple. (Green and purple are used to separate colours from any real affiliations such as politics or gender.) They are also assigned a productivity value which is loosely assigned from a normal distribution of mean 50 and standard deviation 81.85. (These parameters were calibrated to fit the existence of multiple equilibria and a misattribution equilibrium.) To simplify matters for the participants, I inform them that there are 1000 balls in an urn, each with an integer written on them. Half of the balls have a number below 50 and half at or above 50. Negative numbers exist. Participants will be presented with a tool for which they can slide a bar along and see how many of the balls in the urn have a number higher and lower than their selected value. This tool will be visible at all times.

Participants are given a choice on how they wish to earn their bonus payment. They may take a bonus equal to their productivity value in tokens or may apply for one of three jobs which pays a fixed bonus payment of 90 tokens. Participants who unsuccessfully apply are given a bonus payment equal to 0 tokens.

The job application evaluation process is as follows. A single employer wishes to hire 3 workers from the applicant pool. The employer’s profits are positively influenced by the productivity value of the workers they hire. However, the employer is unable to observe the true productivity value of applicants at the point of evaluation. Instead, they observe two features of each applicant: their group identity (green or purple) and a noisy but unbiased signal of the applicants’ true productivity value. The signal is the sum of the productivity value and a stochastic noise element which has a commonly known normal distribution of mean 0 and standard deviation of 81.85. (Participants are informed that for each ball in the first urn, there is a second urn which consists of 1000 balls, each with an integer centred around the first ball. Similar explanations are presented as per the first urn. Moreover, a sliding tool is provided again. Given the participant’s first ball of value x, participants can use a second tool to slide along to see how many balls in their second urn are at or below a certain number.)

The employer uses a robot to conduct the evaluation and hiring process on their behalf. Before the experiment, a random draw determines which one of two robot types is employed throughout the whole procedure. Robot A systematically adjusts signals according to the colour of the applicant: it adds 10 to signals from purple applicants and subtracts 90 from signals of green applicants, and then hires the 3 applicants with the highest adjusted signal values. Robot B hires the applicants that it predicts have the highest productivity given the estimated conditional distributions of productivity values among the likely applicants from each colour computed using the information and incentives given to applicants such as the distribution of types and the colours of previous hires, as well as the distribution of signals in previous rounds. Evidently, robot A practises a naïve taste-based discrimination while robot B employs a fair sophisticated inference which could lead to statistical discrimination should application strategies differ by groups. The description of each robot is left purposefully vague to allow for subsequent treatments to fill in these gaps. In all sessions, robot B is always employed.

Participants are first asked whether they wish to apply for a job or not. They are then incentivised to guess the maximum productivity value among the applicants from each group identity. (A binary scoring rule is employed wherein participants receive 50 tokens if they are within 10 of the true value, 25 tokens if they are within 20 of the true value and nothing otherwise.) After the hiring decisions have been made and the information is given to participants, they are then incentivised to guess which robot type has been employed. To incentivise this guess, I give participants 100 tokens and ask them to distribute these between the two robot types. They receive the coins that they placed under the correct robot type as bonus payment.

Participants repeat this process for twelve rounds. Across all rounds, the participant's group identity and the robot type employed are fixed. In each round, each participant draws a new productivity value. After all rounds, participants are paid their bonus token balance from one of the rounds chosen at random at an exchange rate of 100 tokens = 2 British pounds.

Treatments

Treatments are assigned on the society level and are summarised in a table (not shown). Each session contains two societies each with a randomly drawn treatment. The baseline treatment allows me to test for the mis-attribution of discrimination. I employ two further treatments which allow me to test for the causes and consequences of such respectively.

In the first treatment, I investigate why individuals misattribute discrimination to taste-based sources by relieving participants of the strategic uncertainty in applications. Specifically, I am using this treatment to test whether cursedness leads to misattribution. I hypothesise that this uncertainty leads to misperceptions of the underlying mechanics of the discrimination. In this treatment condition, AVG, I inform participants of the true maximum ability of applicants of each coloured identity after they predict such and before they predict the robot used. This broadens the scope of the information structure I give to participants to include both the realised outcomes of the game but also the strategies played by others. In this treatment, I aim to convey to participants that if they believe that robot B may discriminate when average abilities among applicants differ, then such discrimination may also be occurring.

To test for the consequences of mis-attribution, I employ the treatment INF, wherein I inform participants after round 6 that they have been interacting with robot B and therefore, that the discrimination thus far is statistical in nature. After this round in all treatment arms, I measure two attributes and compare individual responses to the same measures conducted in the baseline treatment. First, I measure individual willingness to pay (WTP) for one-round of affirmative action (AA) wherein the employer is forced to hire at least one worker of each group. Under the policy, a coin is flipped to determine a colour. The side the coin lands on dictates which colour must constitute 2 of the hires, and which colour must constitute one of the hires. This decision is incentivised by the following procedure: participants are free to state a number between 1 and 50; a random participant is chosen and a number x is drawn between 1 and 50. If the number is above the participant’s stated number, then affirmative action is not enacted in the following round. If the number picked is below the number stated by the participant then affirmative action will occur in the next period and the participant is deducted x tokens from their final payment. (This incentivisation method is inspired by the Becker-DeGroot-Marschak mechanism (Becker et al., 1964), however, I take away the strategic uncertainty inherent in the allocation mechanism. Thus, I reduce the incentive to overestimate true valuations via mechanisms like the winner’s curse.)

The second measure establishes participants' perception of the fairness of the situation they are in. I employ this measure directly after the willingness to pay elicitation but before results are finalised. I ask participants to rank, on a 5-point Likert scale, to what extent they consider the hiring process thus far to be fair.

Post-experiment survey
One may be concerned that my measure of WTP for AA may not appropriately capture the intended preferences. Thus, I follow up this measure with a post-experiment survey. In this survey, I ask participants how effective a one-period quota would have increased the share of green hires and applicants in later rounds. I also employ a risk assessment task as pe Gneezy and Potters (1997): individuals are given 100 tokens and asked how many of these coins they wish to invest in a lottery which pays 2.5 times the investment with a probability of one third and nothing otherwise.
Randomization Method
Randomised to a society within each session. Each society is randomised to a treatment.
Randomization Unit
Subsession groups
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
24 societies
Sample size: planned number of observations
384 participants in 24 societies
Sample size (or number of clusters) by treatment arms
384 participants in 24 societies with 12 rounds each.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
With 128 observations (8 societies per treatment), minimum detectable effect is 7.5 percentage point belief difference above Bayesian benchmark if standard deviation of beliefs is 30 (as was in online pilot). Can detect average productivity value differences of applicants of each colour of 26.17 (approximately 1/3 of a standard deviation) with 50 observations per colour. On perceptions of fairness, with my sample size, I have the ability to detect a difference of 1/3 a Likert point difference between treatments with 128 observations per treatment.
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
Norwegian School of Economics IRB
IRB Approval Date
2025-11-10
IRB Approval Number
NHH-IRB-2025-131
Analysis Plan

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Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials