Effort Expenditure for Reward Task (EEfRT)

Background

The Effort-Expenditure for Rewards Task (EEfRT) is a behavioral task that measures an individual's motivation and willingness to exert physical effort for incentives. Michael T. Treadway and colleagues introduced the EEfRT in 2009 to study the relationship of effort-based decision making on anhedonia, the reduced ability to feel pleasure. They based the paradigm on earlier studies that focused on the role of dopamine on a rodent's willingness to work for food rewards.

The EEfRT gives participants two simple choices: select a (physically) easy task and attempt to win some money or select a (physically) harder task and potentially win even more money. The two basic physical tasks offered to participants are as follows: • Easy Task: press the spacebar with your dominant index finger for a minimum of 30 times within 7 seconds.
• Hard Task: press the spacebar with the pinky finger of your non-dominant hand for a minimum of 100 presses within 21 seconds.
By varying factors like the probability of winning the reward (e.g. low vs high win probabilities) and the magnitude of the potential rewards, researchers are then able to analyze an individual's decision-making process. For example, Treadway and colleagues report that patients with current depressive symptoms were less willing to expend effort for the opportunity to earn larger monetary rewards as compared with healthy controls. In addition, the patient group showed less sensitivity to the provided information about the monetary rewards and the associated win probabilities.

While the classic EEfRT focuses on physical effort, the analogous Cognitive Effort Expenditure for Rewards Task (C-EEfRT) measures an individual's willingness to perform demanding mental tasks for a reward.

Task Procedure

The EEfRT familiarizes participants with the task during a short practice phase that runs 4 trials. During the first and second trial, participants must choose the easy and hard task, respectively. For the last two practice trials, participants can choose themselves. If participants fail to choose a task within 5 seconds during practice (and the test), the program randomly chooses a task for them. The actual test phase runs for 20 minutes and participants can work on as many tasks as they can. The number of completed tasks depends on (a) how fast they make their selection, (b) the type of task they select (with the Hard task taking 3 times longer) and (c) how fast they complete the task. The program runs a three 3 reward probabilities (low=0.12, medium=0.5, high=0.88) x 8 different reward magnitudes for the Hard task ($1.08-$4.30), within-participant design. The (potential) reward for the Easy Task is always $1. Each level of reward probability (3) is paired with each level of hard task rewards (8) twice within every 48 trials in the EEfRT Millisecond implementation. The presentation of the different combinations of hard reward tasks x probabilities was randomized for 2 lists of 48 trials and is presentedin fixed order to each participant.
• The expected money for completing 48 trials of the hard task is = $2.77 * 48 * average(0.12, 0.5, 0.88) = $66.48.
• The expected money for completing 48 trials of the easy task is = $1 * (2 * 48) * average(0.12, 0.5, 0.88) = $48.
A maximum payoff can be set in this script, so that if it's reached, the task is terminated.

Each trial sequence begins with the 'Selection Screen' (max. 5seconds) that explicitly presents the reward probabilities and reward magnitudes for the Easy and the Hard tasks. After participants make their choice (or after 5s) by pressing one of two keyboard keys, a 'Ready' screen appears for 1second, followed by the task UI that features an empty meter bar whose level rises with each spacebar press. Once the top of the meter has been reached -or after the assigned task is over (7seconds for the Easy task; 21seconds for the Hard task)- the trial ends, and participants learn if they won the potential reward money (feedback presented for 2seconds). Rewards are only won for completed tasks and only if the program determines the trial to be a 'win' trial (based on the trial's reward probability).

What it Measures

The Effort-Expenditure for Rewards Task (EEfRT) measures an individual's motivation and willingness to exert physical effort for incentives

Psychological domains

• Anticipatory Motivation: The drive to pursue a reward before it is obtained.
• Effort-Based Decision Making: Weighting the subjective value of a reward against the physical energy required to get it.
• Reward Responsiveness: How much a person's behavior changes when the stakes are raised (e.g., doubling the payout).
• Motivational Anhedonia: The diminished drive, interest, or willingness to exert effort to pursue a reward
• Risk and Probability Assessment: Ability to tolerate risk when energy expenditure is at stake
• Subjective Utility Valuation: Cognitive calculations combining effort costs, probability, and reward magnitude to make an optimized choice.

Main Performance Metrics

• proportion Hard Choices: Proportion of time participants selects the hard task; Overall preference metric

Psychiatric Conditions

The EEfRT is extensively used across clinical research because it serves as an objective tool to measure motivational deficits. It has been tested across a wide array of psychiatric, neurological, and physical patient groups.

• Major Depressive Disorder (MDD)
• Bipolar Disorder
• Schizophrenia
• Attention Deficit Hyperactivity Disorder (ADHD)
• Autism Spectrum Disorder (ASD)
• Substance Use Disorders (SUDs)
• Parkinson’s Disease (PD)

Test Variations

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Effort Expenditure for Reward Task (EEfRT).

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Treadway MT, Buckholtz JW, Schwartzman AN, Lambert WE, Zald DH (2009) Worth the ‘EEfRT’? The Effort Expenditure for Rewards Task as an Objective Measure of Motivation and Anhedonia. PLoS ONE 4(8): e6598. doi:10.1371/journal.pone.0006598

Wardle, M., Treadway, M., & De Wit, H. (2012). Caffeine increases psychomotor performance on the effort expenditure for rewards task. Pharmacology, Biochemistry, and Behavior, 102(4), 526-31.

Barch, D., Treadway, M., Schoen, N., & Goodman, Sherryl. (2014). Effort, Anhedonia, and Function in Schizophrenia: Reduced Effort Allocation Predicts Amotivation and Functional Impairment. Journal of Abnormal Psychology, 123(2), 387-397.

Hughes, D., Yates, M., Morton, E., & Smillie, L. (2015). Asymmetric frontal cortical activity predicts effort expenditure for reward. Social Cognitive and Affective Neuroscience, 10(7), 1015-1019.

Treadway, M., Peterman, J., Zald, D., & Park, S. (2015). Impaired effort allocation in patients with schizophrenia. Schizophrenia Research, 161(2-3), 382-5.

Lopez-Gamundi, P & Wardle, MC (2018). The cognitive effort expenditure for rewards task (C-EEfRT): A novel measure of willingness to expend cognitive effort. Psychol Assess, Sep;30(9):1237-1248. doi: 10.1037/pas0000563. Epub 2018 Apr 5. PMID: 29620381.

Horne, S. J., Topp, T. E., & Quigley, L. (2021). Depression and the willingness to expend cognitive and physical effort for rewards: A systematic review. Clinical Psychology Review, 88, Article 102065. https://doi.org/10.1016/j.cpr.2021.102065

Webber, H. E., Lopez-Gamundi, P., Stamatovich, S. N., de Wit, H., & Wardle, M. C. (2021). Using pharmacological manipulations to study the role of dopamine in human reward functioning: A review of studies in healthy adults. Neuroscience and Biobehavioral Reviews, 120, 123–158. https://doi.org/10.1016/j.neubiorev.2020.11.004