Appendix B

The computer interface used for the experiment

This appendix describes the details of the computer interface used during the experiment described in Chapter 4. The interface was created using the z-Tree software (Fischbacher, 2007). Via this interface, subjects received information on the computer screen and communicated their decisions by clicking on-screen buttons using the mouse.

We present the most important screens of the computer interface. For this purpose, all text on the screens has been translated from the original Dutch. The screens shown here are taken from the practice periods, which preceded the actual experiment in each session. The screens from the practice periods look identical to the screens used during the later periods.

At the start of each session, when subjects entered the laboratory, all computers were running the interface showing Screen 1. This screen was used to assign subjects to a computer and instructed subjects to start reading the instructions once they were seated. When subjects had finished reading the instructions, they were asked to click “continue” and were subsequently presented with Screen 2. This screen announces the start of the practice periods and informs subjects that their participant number is “1.” The participant number was “1” for all participants, in order to ensure that the computer interface looked the same to all subjects.

Screen 1 Welcome.

Screen 2 Start of practice periods.

As soon as all subjects had indicated ...

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