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Field
Experimental Design (Public)
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Before
Treatment 1:
Cognitive load is induced throughout the treatment with Stroop tasks. There are three difficulty levels, baseline, congruent and dissimilar. In the baseline Stroop tasks, subject are presented with a name of a color, written in letters of that same color. To the right of the word there is a bullet where the name of the color, again, is written. Subject should simply choose the bullet to successfully complete a baseline Stroop task. In the congruent Stroop tasks, subjects are presented with a name of a color, written in letters of that same color. To the right of the word there is a list of six bullets, each representing a color. The subject should choose the bullet that corresponds to the word on the left. In the dissimilar Stroop tasks, subjects are presented with a name of a color, written in letters of a different color. To the right of the word there is a list of six colors. The subject should choose the color that corresponds to the color of the letters of the word on the left.
All subjects perform all tasks, time perception, time preferences elicitation and numeracy tasks with all three types of Stroop tasks (in a group of 2, 3 or 4 tasks at the time) generating a disturbing cognitive load.
In the time perception task, Stroop tasks are solved during the interval that is to be estimated. In the time preferences elicitation and the numeracy tasks, the screen is divided in two. The multiple price list/multiplication task appears on the left side while on the right side Stroop tasks (2, 3 or 4 at the time) pop up randomly (arrival determined by a poisson process).
The design is within-subject. Hence all subject do all tasks with all three levels of cognitive load.
Time perception is measured over three intervals. A random number between 7 and 12 seconds, a random number between 13 and 18 seconds and a random number between 19 and 24 seconds, all intervals with all three levels of cognitive load induced by Stroop tasks.
Time preferences are measured using a double multiple price list. There are 4 different versions of the MPL in terms of time: today vs. in one week, today vs. in three weeks, in one week vs. in three weeks and in three weeks vs. in six weeks. For each of the four time schemes, there are two versions of the MPL, one with a larger range than the other. In order to control for changes in concavity of the utility function as cognitive load increases, risk preferences are measured using MPL in the baseline Stroop condition and the dissimilar Stroop (high cognitive load). Here also, are two lists of different range presented in each of the two Stroop conditions.
Treatment 2:
Time preferences, time perception, performance on numeracy tasks and future time perspective are measured under two levels of arousal induced by external tempo generated by a metronome (in headphones).
The method for measuring time and risk preferences and numeracy are the same as in treatment 1, except that there is now no Stroop tasks popping up, instead, subjects listen two tempo of either 120 Bpm or 165 Bpm in headphones while solving the tasks.
Again, the design is within-subject, hence all subjects perform all tasks with both high and low tempo.
In order to avoid counting time during the time perception task, subjects solve a series of baseline Stroop tasks during the time intervals that are to be estimated.
The future time perspective is measured using a scrambled sentence task. Under time pressure the subject have to unscramble words and form sentences. In all tasks, one can either construct a future oriented sentence or a present oriented sentence. The share of future oriented sentences is the subjects measure of future time perspective. All subjects do two versions of the future time perspective task, one with 120 bpm in the headphones, the other with 165 bpm in the headphones. Which version is coupled with which beat is randomized.
For both treatment 1 and treatment 2, the order of tasks is randomized for each session.
Finally, at the end of the session, subjects are asked to estimate how long the experiment has taken.
Background questions that will be collected are individual information (age, gender, income, family status), self-reported attitudes towards risk preferences, time preferences and future time perception.
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After
Treatment 1:
Cognitive load is induced throughout the treatment with Stroop tasks. There are two difficulty levels, congruent and dissimilar. In the congruent Stroop tasks, subjects are presented with a name of a color, written in letters of that same color. To the right of the word there is a list of six bullets, each representing a color. The subject should choose the bullet that corresponds to the word on the left. In the dissimilar Stroop tasks, subjects are presented with a name of a color, written in letters of a different color. To the right of the word there is a list of six colors. The subject should choose the color that corresponds to the color of the letters of the word on the left.
All subjects perform all tasks, time perception, time preferences elicitation and numeracy tasks with both types of Stroop tasks, generating a disturbing cognitive load.
In the time perception task, Stroop tasks are solved during the interval that is to be estimated. In the time preferences elicitation and the numeracy tasks stroop tasks pop up from time to time, demanding attention. Once they have been solved, they disappear and the subject can go back to the multiple price list/numeracy task.
The design is within-subject. Hence all subject do all tasks with all three levels of cognitive load.
Time perception is measured over six intervals, 7, 11, 15, 23, 34 and 41 seconds using prospective production. Subjects are given the time interval they are to produce and instructed to press a start button to start the interval. They are told to press a stop button when they think the indicated time has passed. During the time interval, subjects solve stroop tasks that are either congruent or dissimilar.
Time preferences are measured using a multiple price list. There are 5 different versions of the MPL in terms of time. All list have today as the left side option. The right side option is 1, 2, 3, 6 and 9 weeks from now. In addition, for the 0-1 and the 0-6 versions of the MPL, there are two versions with different price range.
Numeracy is measured with cognitive reflection questions, taken from Frederick (2005) and Toplak et al. (2014).
Treatment 2:
Time preferences, time perception, performance on numeracy tasks and future time perspective are measured under two levels of arousal induced by external tempo generated by a metronome (in headphones).
The method for measuring time preferences and numeracy are the same as in treatment 1, except that there is now no Stroop tasks popping up, instead, subjects listen two tempo of either 120 Bpm or 165 Bpm in headphones while solving the tasks.
Again, the design is within-subject, hence all subjects perform all tasks with both high and low tempo.
In order to avoid counting time during the time perception task, subjects solve a series of baseline Stroop tasks during the time intervals that are to be estimated.
The future time perspective is measured using a scrambled sentence task. Under time pressure the subject have to unscramble words and form sentences. In all tasks, one can either construct a future oriented sentence or a present oriented sentence. The share of future oriented sentences is the subjects measure of future time perspective. All subjects do two versions of the future time perspective task, one with 120 bpm in the headphones, the other with 165 bpm in the headphones. Which version is coupled with which beat is randomized.
For both treatment 1 and treatment 2, the order of tasks is randomized in the following way:
By session, the order of Time Preferences, time perception and numeracy is set to one of the 6 possible combinations (rotates across sessions). If in a session the order is Time pref - time perception- numeracy, then, subjects solve the tasks in the following order: Time pref(random if dissimilar or congruent/ 120 or 165) - time perception (random if dissimilar or congruent/ 120 or 165) - numeracy (random if dissimilar or congruent/ 120 or 165) - Time pref (the remaining treatment, depending on randomization in first part) - time perception (remaining treatment) - numeracy (remaining treatment).
Finally, at the end of the session, subjects are asked to estimate how long the experiment has taken.
Background questions that will be collected are individual information (age, gender, income, family status), self-reported attitudes towards risk preferences, time preferences, a short big 5 questionnaire and future time perception.
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Field
Randomization Method
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Before
The design is within subject and treatment 1 and treatment 2 are independent. Hence, there will be no randomization into treatments.
The order of the tasks is randomized (by a computer) for each session. For the time preference and risk preference elicitation, there are three versions of the MPL in treatment 1 and two versions in treatment 2. Which of the lists is matched with which version is randomized by a computer for each subject.
The length of the intervals to be estimated in the time perception tasks is always in the intervals [8,12], [13,17] and [18,24], but the exact number of second is randomly drawn by a computer for each subject.
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After
The design is within subject and treatment 1 and treatment 2 are independent. Hence, there will be no randomization into treatments.
For both treatment 1 and treatment 2, the order of tasks is randomized in the following way:
By session, the order of Time Preferences, time perception and numeracy is set to one of the 6 possible combinations (rotates across sessions). If in a session the order is Time pref - time perception- numeracy, then, subjects solve the tasks in the following order: Time pref(random if dissimilar or congruent/ 120 or 165) - time perception (random if dissimilar or congruent/ 120 or 165) - numeracy (random if dissimilar or congruent/ 120 or 165) - Time pref (the remaining treatment, depending on randomization in first part) - time perception (remaing treatment) - numeracy (remaining treatment).
In the tempo treatment, the future perspective is added to the list above and randomized in the same way,
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