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Temptation: Immediacy and Certainty

Last registered on October 28, 2019


Trial Information

General Information

Temptation: Immediacy and Certainty
Initial registration date
September 12, 2019
Last updated
October 28, 2019, 2:20 PM EDT



Primary Investigator


Other Primary Investigator(s)

Additional Trial Information

In development
Start date
End date
Secondary IDs
A choice is most tempting when it is both immediate and certain. Prevailing experimental measures of static present-bias rely on the random incentive scheme (RIS) to gather rich data from subjects. Recent studies show that RIS adds background risk to decisions, thereby increasing risk-taking behavior. Evidence has shown that the immediacy effect is significantly moderated (or even eliminated) by uncertainty. Thus estimates of the present-bias factor $\beta$ are possibly biased upward toward unity, underestimating present-bias intensity. I conduct a framed field experiment that determines whether uncertainty indeed diminishes the immediacy effect by using real-effort tasks to approximate immediate and certain utility flows. Subjects allocate tasks using convex time budgets under both RIS and certain implementation. I compare within-subject estimates of the quasi-hyperbolic present-bias factor under these two mechanisms, assuming convex effort costs. I type individuals as present- or future-biased under each mechanism, which provides data on the interaction between the immediacy and certainty effects within subjects. I also report how the introduction of uncertainty affects the present-bias parameter on average, which would be some of the first incentivized evidence of the effect of uncertainty on immediacy.
External Link(s)

Registration Citation

Reddinger, Lucas. 2019. "Temptation: Immediacy and Certainty." AEA RCT Registry. October 28.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Primary outcomes of interest are the real-effort task allocations chosen by subjects between two weeks.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
The intake questionnaire includes a short demographic survey; these data will be used to predict attrition and may also be used as controls in prediction of primary results.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Subjects must complete an intake questionnaire that tests comprehension of the experimental instructions; subjects must answer all questions correctly to be enrolled in the trial.

On Day 1 (e.g., Monday of Week 1), subjects are asked to allocate approximately 30 minutes of work between Day 2 (e.g., Wednesday of Week 1) and Day 3 (e.g., Wednesday of Week 2). On Day 2, subjects are again asked to allocate work between Day 2 and Day 3. For each subject, an independent fair coin toss determines whether decisions from Day 1 or Day 2 are implemented.

If a subject is assigned to the “Uncertain-Day” treatment, she learns the result of this coin toss after her decisions on Day 2. If a subject is assigned to the “Certain-Day” treatment, she learns the result of this coin toss before her decisions on Day 2.

On each day that decisions are made, subjects are asked to allocate a fixed present value budget of real-effort tasks between Days 2 and 3.
Subjects make allocation decisions for each of five gross interest rates R ∈ {0.5, 0.75, 1, 1.25, 1.5}.

If a subject is assigned to the “Uncertain-List” treatment, after she makes all of her decisions, one of her decisions from the selected day is chosen at random with uniform probability to be implemented. If a subject is assigned to the “Certain-List” treatment, her decision from the selected day for the gross interest rate R = 1.25 is chosen with certainty to be implemented.

Each subject is assigned to a “Day” treatment and a “List” treatment, resulting in a two-by-two factorial design. Each subject is fully informed of the procedures and mechanisms used in her assigned treatment.
Experimental Design Details
Randomization Method
Subjects are enrolled in the order in which they complete the intake questionnaire. Treatments are assigned to subjects using a round-robin algorithm as subjects are enrolled. Randomization of gross interest rates is done in advance using a computer program (using unique seeds to permit replication).
Randomization Unit
Subjects are individually assigned to one of the four treatments.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
The trial will have 192 to 208 subjects; each subject represents a cluster.
Sample size: planned number of observations
Each subject makes 20 allocation decisions. The trial will thus yield 3840 to 4160 observations.
Sample size (or number of clusters) by treatment arms
Certain-Day-Certain-List: 64 subjects.
Certain-Day-Uncertain-List: 64 subjects.
Uncertain-Day-Certain-List: 32 subjects.
Uncertain-Day-Uncertain-List: 32 subjects.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
UCSB, Office of Research, Human Subjects Committee
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials