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Instructions for Zenda
Introduction
Zenda is a simple card game that you play with one other person. Each game of Zenda will consist of 15-25 rounds of play. Players are matched up randomly each round, so that you will play a different person each round. You will never know the identity of the person you are paired with, nor will that person know your identity. All of your choices and earnings in the experiment will be confidential.
In Zenda, you will be playing for chips. The value of the chips corresponds to cash earnings for you. In particular, each chip you earn is worth 4 cents. So if you earn 5 chips in a round, you earn 20 cents in the round. If you earn 9 chips, you earn 36 cents in that round. The earnings that you make each round will be totaled by the experimenter and paid to you privately and in cash at the end of the experiment. No other subject will know your earnings.
After each round is finished, a dialog box will be displayed informing you of this fact and asking you to wait until the other players are finished. Please click on the "OK" button as soon as you have read and understood the material since the system will wait until everyone has clicked "OK" before it proceeds. Dialog boxes will be displayed at other times during the game; after you have read and understood a dialog box, click "OK".
Please do not talk to any other player or look at any other player's screen. If you have a problem, please raise your hand and someone will come to help you. We expect the experiment to last about 50 minutes.
Information about you
The first thing that you see will be a panel that asks for information about you. The University requires that we collect this information since we are going to give you money. This information is not recorded as part of the experimental data; it is only there to satisfy University rules about dispersing money. In the experiment you are only identified by a "player number" and we maintain strict anonymity. No one in the experiment will ever know your name, your choices, or your earnings.
Phase 1 of Zenda
There are two phases to Zenda. Phase 1 is called Push-Pull. When you play Push-Pull, you will see two cards in front of you, two cards in front of the other player, and a pile of chips between the two of you. The pile of chips between you is the "pot"; it is the source of the payments.
Your cards are labeled Push and Pull. You can choose to play a card by clicking on it with the mouse. When you choose a card it will be highlighted but your choice will not be final until you click the "Confirm choice" button. If you choose the pull card, then you will pull the number of chips on that card from the pot to your pile of chips. If you choose the push card, then you will push the number of chips on that card from the pot to the other player.
Note that the chips that you push or pull come from of the pot in the middle of the table, not from either player's pile of chips.
When both players have made their decision to push or to pull, you will see a message appear telling you what has happened and your earnings will be displayed. When all players have have made their choices, you will see a panel and a beep will announce the start of a new round. Click on the "OK" button on the panel to start playing the new round.
An Example
Suppose that your pull card is 4 and your push card is 6 and suppose the other player has a pull card of 3 and a push card of 7. Your payoffs look like this:
Other player's choice
Pull 3 Push 7
Your choice Pull 4 4 11 <---- your payoffs
Push 6 0 7 <-----your payoffs
The payoffs to the other player look like this:
Your choice
Pull 4 Push 6
Other player's choice Pull 3 3 9 <---- other player's payoffs
Push 7 0 6 <---- other player's payoffs
Each round you choose whether to push or pull, and the other player does the same. After 15 rounds, Push-Pull will end , and Phase 2 of Zenda will begin.
Summary Phase 1 of Zenda
Choose to push or pull and click "Confirm choice." If you push, the other player gets the number of chips on your push card; if you pull, you get the number of chips on your pull card. When you see a dialog box that tells you the round has ended, click on "OK" so that the play can proceed.
Phase 2 of Zenda
In this phase you have a new option that we call Pay-for-Push. Everything else about Zenda will be the same as in Phase 1. In particular, during each round of Phase 2 you will be randomly paired with another subject each time you play Zenda.
On your screen you will see a new button labeled "Confirm payment" and a slider. You can use the slider to offer a payment to the other player to encourage them to choose to play the push card..
You set this payment by moving the slider up or down. As you do this you will move chips from your pile of chips to a pile in front of the other player. When you are satisfied with your decision about how much you are willing to pay the other player, you click on your "Confirm payment" button. Neither player will see how much the other player is willing to pay until both players have clicked on their "Confirm payment" button. Once you've seen how much the other player has offered to pay you to push, you can decide whether to push or to pull. Your payoff will be as before but now the payment you make will be subtracted from your pile of chips if the other player chooses to push. If the other player chooses to pull, then you will get your payment back. Likewise, if
you choose to push, the payment offered to you by the other player will be added to your earnings, and subtracted from the other players earnings.
Summary of Phase 2 of Zenda
In each round of play you will move your slider to determine how many chips you want to pay the other player to Push. Once you have decided this, you click on your "Set Payment" button. When both players have clicked their "Confirm payment" button, each will be able to see how much the other player has offered. At that point, each player can choose whether to push or pull as before. When both players have clicked their "Confirm payment" button, each player sees the payoffs and a new round begins.
You will play 25 rounds of Pay-for-Push.
Things to remember
1. You play against a new person every time.
2. You should click "OK" as soon as you have read and understood a message.
3. You are playing for real money; each chip is worth 4 cents.
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.