**Treatment and Prediction**
The experiment aims to examine whether the future tense reference influences people’s preference for intertemporal choice. The future payment in the treatment group will be described as “After Y weeks will receive Z tokens.”; while that in the control group will be described as “After Y weeks, receive Z tokens.” The only difference between the two descriptions is that “will” was added in the treatment group and was replaced by a “,” (comma) in the control group. Importantly, in Chinese characters, “will” and a comma both occupy one-word space. As the linguistic-savings hypothesis (LSH) predicts, the subjects in the treatment group (future-tense condition) should exhibit less patience than those in the control group (present-tense condition).
**Binary Choice Design**
Instead of the popular multiple price lists method, this study adopted a binary choice design. Subjects were in a scenario in which they decide to receive payment either today or in the future. The scenario was composed of 72 questions and was displayed sequentially. In each question, a subject had to choose between an immediate payment and a delayed payment.
To apply eye-tracking in the study, we simplified the screen as much as possible. First, the amount of immediate payment “X” was displayed in the left-upper corner of the screen. Second, the description of future payment “After Y weeks (will/,) receive Z tokens” was displayed at the upper center of the screen. Lastly, two rectangles indicating “today” and “future” were displayed at the bottom of the screen, and which one is on the left is randomly decided.
College subjects will be recruited through Taiwan Social Sciences Experimental Laboratory (TASSEL) at National Taiwan University. Experiments will be conducted in person and programmed through MATLAB. To start the experiment, the computer will randomly assign each subject to either the control group or the treatment group (between-subjects design). Also, the experimenter will not monitor the subjects’ responses throughout the experiment (double-blind design).
The experiment is divided into two stages. At the beginning of a stage, a subject will be informed the immediate payment was 100 or 120 tokens. Then, he will compare this immediate payment to a future payment which has nine different amounts (110, 120, 130, …, 190 tokens) and four different durations (one, two, four, or eight weeks). To control the order effect, two stages with different immediate payments are in random order. Also, nine different amounts and four different durations of future payments are randomly decided.
After all intertemporal choices in the two stages are made, the computer program will randomly draw one decision from the first stage and the other from the second stage, to realize the payoff. The tokens will be exchanged for real money with the conversion rate of 10 tokens = $12 New Taiwan Dollar (NTD). The money will be paid by a wire transfer, regardless the paid time is today or several weeks later. Finally, subjects are asked to complete a questionnaire with demographic characteristics and paid $100 NTD in cash for their participation.