Appendix A. Complete list of English-language questionnaires, with full items
Note: The order of the questionnaire sections will be the same as presented here, but the order of
the manipulation check items will be randomized for every participant.
Postgame questionnaire
Demographic information
To begin with, we would like to ask you for some basic demographic information about you. This
information will give us a sense of the different types of people in our study, which will help us
describe our study sample when reporting our data.
How old are you? [type in answer] years
What is your gender? [male/female/ don’t want to answer]
On average, how many hours per week do you play computer and/or video games? Please type in 0 if
you do not play computer or video games at all. [type in answer] hours
Manipulation checks
Note: Randomized order
To begin with, we want to ask you a few questions about the experience you just had when playing
NBA Jam. Please indicate how much agree or disagree with each of the following statements. (1 =
Strongly Disagree and 7 = Strongly Agree)
I expected my teammate to be supportive.
My teammate was supportive.
I felt successful while playing the game.
The game was difficult to play.
My teammate was likable.
My teammate was competent during the video game.
Did you know your teammate before you played the game together [yes/no] – filter question
If yes:
How well do you know your teammate? [1 – barely (you, e.g., saw him in a lecture or on the bus
without really talking to him) to 5 – very well (e.g., you are close friends, are/have been roommates)]
Break in the questionnaire, so the experimenter can briefly explain
the reciprocity expectations and prosocial behavior measures (see
below).
RECIPROCITY EXPECTATIONS
[Experimenters will be instructed to tell participants the following before participants are able to
proceed to the following electronic questionnaire regarding their prosocial behaviors towards
teammates]
Note: For the German participants, the words dollar and dime will be replaced by Euro and 10 Euro
cents
“Now comes the part about the money. As part of your compensation you get $1.00 for participating
today. However, you will now have the opportunity to engage in a money transaction game with
your teammate who is also getting $1.00. Please read the instructions in the questionnaire carefully,
but for clarity here are the rules: You and your teammate have 10 dimes. You can donate any
number of the dimes to your teammate and keep as many dimes as you like. Any number of dimes
you donate will double in value for your teammate but any dimes you keep will not. Likewise, the
number of dimes your teammate donates to you will double in value for you but the dimes your
teammate keeps will not. Is that clear? Do you have any questions?”
[To be presented in the electronic questionnaire]
You will be deciding how many dimes you would like to donate to your teammate at the same time
as your teammate will be deciding how many dimes to donate to you. Any number of dimes you
donate will double in value for your teammate but any dimes you keep will not. For example, if you
donate 5 dimes your teammate will receive 1 dollar and if you keep 5 dimes you will only receive 50
cents. Likewise, the number of dimes your teammate donates to you will double in value for you but
the dimes your teammate keeps will not.
1. Out of the 10 dimes possible to donate, how many dimes do you think your teammate will choose
to donate to you?
❍ No Dimes
❍ 1 Dime
❍ 2 Dimes
❍ 3 Dimes
❍ 4 Dimes
❍ 5 Dimes
❍ 6 Dimes
❍ 7 Dimes
❍ 8 Dimes
❍ 9 Dimes
❍ 10 Dimes
PROSOCIAL BEHAVIOR
You have 10 dimes to do with as you please. You can donate any number of the dimes to your
teammate and keep as many dimes as you like. Any number of dimes you donate will double in value
for your teammate but any dimes you keep will not. Likewise, the number of dimes your teammate
donates to you will double in value for you but the dimes your teammate keeps will not.
1. Please indicate how many dimes you would like to donate to your teammate by selecting a
number below.
❍ No Dimes
❍ 1 Dime
❍ 2 Dimes
❍ 3 Dimes
❍ 4 Dimes
❍ 5 Dimes
❍ 6 Dimes
❍ 7 Dimes
❍ 8 Dimes
❍ 9 Dimes
❍ 10 Dimes
Final questions
Did you nothing anything particular during the study? [open-ended]
Do you have any comments or remarks about the study? [open-ended]
Conclusion
So, that’s all we’ve got today! Thanks so much for helping us out with this study. We will contact you
after the study has concluded if you are interested in further results, and we’ll also contact you if you
are one of the $25 Amazon drawing winners. For these reasons, we would like to request your email
address one more time, to confirm your participation. [fill in].
Thanks again! Please let your experimenter know that you are done with the questionnaire now.