Experimental Design Details
We conduct an online survey experiment on individual decision-making. The main feature of our experimental setup are multiple pairwise intertemporal choices that participants make after reading computerized instructions. In each intertemporal choice, subjects choose between two Amazon gift cards, gift card A and gift card B. Each gift card consists of two components:
an observable value x;
a date t during which the gift card would be made available (via email) to subjects.
In all choices, the value of gift card A, x_a, the value of gift card B, x_b, and the date of gift card A, t_a, remain constant. Between choices, we vary only the date of gift card B, t_b. In addition, in each choice, we have x_a<x_b and t_a<t_b: gift card A is always the sooner-smaller alternative and gift card B is always the larger-later alternative.
In addition, we elicit from some subjects (depending on the treatment condition, see below) subjects’ perception of time regarding t_a and particular values of t_b. In doing so, we build on the method of (Zauberman, Kim, Malkoc, and Bettman, 2009, Journal of Marketing Research).
Our treatments follow a 4x2 factorial design. In the first dimension of the design, we vary the value of t_b across four between-subjects treatments. In the second dimension, we vary whether subjects only make intertemporal choices or whether we elicit their time perception as well.
In all treatments, we set x_a= €70, x_b= €71, and t_a= 9 days. Between treatments, we set t_bequal to the following values in the order in which they are displayed:
Condition A: t_b equals 10 days, 20 days, 25, days, 30 days, 40 days, 45 days, and 50 days.
Condition B: t_b equals 50 days, 45 days, 40, days, 30 days, 25 days, 20 days, and 10 days.
Condition C: t_b equals 10 days, 11 days, 12, days, 13 days, and 50 days.
Condition D: t_b equals 50 days, 49 days, 48, days, 47 days, and 10 days.
Condition without time perception: Subjects only make the intertemporal choices.
Condition with time perception: In addition to the intertemporal choices, we elicit subjects’ time perception four times. In A-B, we elicit subjects’ time perception of t_a=9 days and t_b= 30 days after they made their fourth choice as well as their time perception t_a=9 days and t_b= 50 in A, = 10 in B after they made their final choice. In C-D, we elicit subjects’ time perception of t_a=9 days and t_b= 10 in C, =50 in D days after they made their first choice as well as their time perception t_a=9 days and t_b= 50 in C, = 10 in D after their final choice.
In conditions A and B, we are interested in subjects’ choices with t_b=20,25,30,40.
In conditions C and D, we are interested in subjects’ choices with t_b=10,50.
If we elicit time perception, we are interested in the within-subject differences between subjects’ time perception of t_a and t_b after their fourth choice as well as the within-subject differences between t_a and t_b after subjects’ final choice.
Hypothesis and Tests
In all conditions with and without time perception elicitation, we test whether more subjects choose patiently (ie, gift card B) in A than in B and whether more subjects choose patiently (ie, gift card B) in D than in C.
In the conditions with time perception, we test whether the difference between t_a=9 and t_b= 30 is greater in B than in A, whether the difference between t_a=9 and t_b= 10 is greater in C than in D, and whether t_a=9 and t_b= 50 is greater in C than in D.
We consider two samples. First, we consider all subjects who participated in our experiment. Second, we consider subjects who passed our attention checks (see below), made consistent choices (ie whenever they were patient for some value of t_b they are not impatient for any smaller values of t_b, or whenever they were impatient for some value of t_b they are not patient for any greater values of t_b), and spend a reasonable amount of time completing the experiment.
The attention check refers to the following task each subject performs during the experiment. On each decision screen, we ask subjects to type the values of t_a and t_b of the current choice options into respective text fields. Subjects can type into these text fields anything. Subjects pass our attention check if they state the actual values of t_a and t_b of the current choice options. Subjects who make a mistake for at least one of these values fail our attention check.
Randomization and sample size
Subjects are randomly assigned to one of 4x2 (between-subjects) treatments. We aim for 825-875 subjects per treatment