Experimental Design
2. Treatments
We will conduct eight treatments, numbered according to the corresponding subsections below.
2.1 Baseline
In the Baseline of their original study, Dana, Weber and Kuang (2007) (DWK) ran a binary dictator game experiment with student participants in which dictators had to choose between two alternatives, A and B. In alternative A, the dictator would earn 6 and the recipient 1; in alternative B, each would earn 5. About three quarters chose the fair alternative B. In DWK’s Hidden information treatment, however, dictators did not initially know the payoffs of the recipient in each alternative: they knew that dictators themselves would get 6 in A and 5 in B, but the payoffs to the recipient was either, with equal probabilities, 1 in A and 5 in B (conflicting), or 5 in A and 1 in B (aligned). This uncertainty, however, could be costlessly resolved by the dictators simply by clicking a button on the screen. About half of dictators did not click the button, thus remaining ignorant about the recipient’s payoffs – and among those who were actually in the state of conflicting interests, all chose the selfish option A. Thus, the option to stay ignorant substantially reduced the resulting generosity.
Conflicting Aligned
Dictator Recipient Dictator Recipient
A 6 1 6 5
B 5 5 5 1
Table 1. Payoffs in DKW’s Hidden Information treatment.
Our Baseline treatment replicates the incentives and main design of DWK’s baseline treatment. All instructions are given on-screen. After an initial explanation (see Figure 1) and a simple comprehension check, dictators make their choice between options A and B.
Figure 1. First instruction screen to Dictators (Person 1) and Recipients (Person 2) in all treatments. In treatments with a third-party Informer (Person 3), the Informer sees a different first screen.
After a quick attention check (entering a given number, time limit of 45 seconds), dictators are faced with the following screen:
Figure 2. Second screen, dictators, Baseline.
Our alternative treatments are Hidden Information; Hypothetical Informer; Informer; Informer—Punishment; Hidden Information—Separate Screens; Hypothetical Informer—Separate Screens; Informer—Separate Screens.
2.2 Hidden Information
The Hidden Information treatment is like the Hidden Information treatment of DWK.
The first screen is identical to that in Baseline. The second screen, identical for Dictators and Recipients, looks like this:
Figure 3. Second screen, all subjects, Hidden Information.
When pressing “continue”, dictators are sent to a decision screen where they are asked to choose either A, B, or revealing information about which table applies:
Figure 4. Dictators’ initial choice screen, Hidden Information.
If the Dictator chooses either A or B, the game is over and the payoffs are realized. However, if the dictator instead chooses `Reveal’, then she is directed to the allocation decision screen with the payoffs shown, as in Figure 5.
Figure 5. Dictators’ allocation choice after revealing payoffs, Hidden Information. The aligned-interests payoffs are shown in this screen shot.
2.3 Hypothetical Informer
For Dictators, the Hypothetical Informer treatment is identical to Hidden Information until and including the screen shown in Figure 4. However, after the screen shown in Figure 4 (and before getting to see the correct table, if choosing to reveal information), dictators get to see an additional screen with the following instructions:
“You chose [option A/option B/to reveal information about which table is being used for your pair].
A third participant, Person 3, has been matched with your pair. Person 3 answers the following question: “In the case that Person 1 did not reveal which table is being used for their pair, would you prefer to overturn their decision, providing this information to Person 1?” The question is a purely hypothetical one, however; Person 3 is not able to provide any information to you. Thus, you will get to know which table is used only if you requested this information yourself. Person 3’s payoff is independent of their choice.
On the next screen, you will be informed about Person 3’s decision. You will also receive information about the correct table if you requested it. You are then asked to make your choice between options A and B.
Note that we will ask you to choose between options A and B even if you already did so on the previous decision screen. Your previous choice will then be filled out by default, and you can confirm it by pressing the “OK” button. If you wish to change your choice at this point, however, you are free to do so. Payoffs to both you and Person 2 will be based on your final choices on the next screen.”
After this, the dictator is informed about the informer’s decision and also, if the dictator has chosen to reveal information, about the correct table. On the same screen, the dictator makes their final allocation decision and the game ends.
2.4 Informer
The Informer treatment is like the Hypothetical Informer treatment except that the Informer’s choice is actually implemented. The text appearing after Dictators’ information-choice screen is now:
“You chose [option A/option B/to reveal information about which table is being used for your pair].
A third participant, Person 3, has been matched with your pair. Person 3 answers the following question: “In the case that Person 1 did not reveal which table is being used for their pair, would you prefer to overturn their decision, providing this information to Person 1?” If Person 3 answers yes, we will show you which table is being used, regardless of whether you chose yourself to reveal this information. If Person 3 answers no, we will show you which table is used only if you requested this information yourself. Person 3’s payoff is independent of their choice.
On the next screen, you will be informed about Person 3’s decision and then make your choice between options A and B.
Note that we will ask you to choose between options A and B even if you already did so on the previous decision screen. Your previous choice will then be filled out by default, and you can confirm it by pressing the “OK” button. If you wish to change your choice at this point, however, you are free to do so. Payoffs to both you and Person 2 will be based on your final choices on the next screen.”
The Informer then makes their choice; Dictators are informed about this choice, get information about the correct table if either party chose to reveal it, and make their final choice between options A and B.
2.5 Informer—Bonus
The Informer—Bonus treatment is similar to Informer, except that the Dictator now has a third choice to make (i. information, ii. allocation, iii. bonus): After getting to know whether the Informer chose to impose information on him or not, the Dictator can now choose to increase the Informer’s payoff by 1 ECU, covered by the experimenters.
The text appearing after the information choice screen is now:
“You chose [option A/option B/to reveal information about which table is being used for your pair].
A third participant, Person 3, has been matched with your pair. Person 3 answers the following question: “In the case that Person 1 did not reveal which table is being used for their pair, would you prefer to overturn their decision, providing this information to Person 1?” If Person 3 answers yes, we will show you which table is being used, regardless of whether you chose yourself to reveal this information. If Person 3 answers no, we will show you which table is used only if you requested this information yourself. Person 3’s payoff is independent of their choice.
On the next screen, you will be informed about Person 3’s decision and then make your choice between options A and B.
Note that we will ask you to choose between options A and B even if you already did so in the previous decision screen. Your previous choice will then be filled out by default, and you can confirm it by pressing the “OK” button. If you wish to change your choice at this point, however, you are free to do so. Payoffs to both you and Person 2 will be based on your final choices on the next screen.
Finally, we will ask you whether you want to increase Person 3’s payoff by 1 ECU. If you use this option, the extra payoff to Person 3 is covered by the experimenters, not by yourself.”
Informers get a similar instruction screen providing them with the same information.
After Dictators make their final A/B choice, they face a new screen, where they are reminded of their own and the Informer’s information choices, and are asked whether they prefer to increase Person 3’s payoff by 1 ECU. It is specified that Person 1’s own payoff is not affected by this choice. When both have made their choices, the Dictator is asked for their reasons to increase Person 3’s payoff or not (open-ended question), before the game ends.
2.6 Hidden Information—Separate Screens
To examine whether the very knowledge that others may impose information cause dictators to seek information themselves, we include the three separate-screens treatments.
The Hidden Information—Separate Screens treatment is like Hidden Information, except that the information and allocation decisions are in separate screens.
Figure 6. Dictators’ information-choice screen, Hidden Information—Separate Screens
Figure 6 shows the information-choice screen. After this screen, the dictator is directed to the allocation decision screen (Figure 7). If the dictator chose information, the payoffs are displayed. Otherwise, the unknown payoffs are represented by a `?’.
Figure 7. Dictators’ allocation-choice screen, Hidden Information—Separate Screens, with payoff state not revealed. If payoff state is instead revealed, the both instances of `?’ are instead replaced with the appropriate number.
2.7 Hypothetical Informer—Separate Screens
The Hypothetical Informer—Separate Screens treatment uses th