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).
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.