from otree.api import *
import random
doc = """
This is a one-shot "Prisoner's Dilemma". Two players are asked separately
whether they want to cooperate or defect. Their choices directly determine the
payoffs.
"""
class C(BaseConstants):
NAME_IN_URL = 'prisoner'
PLAYERS_PER_GROUP = 2
NUM_ROUNDS = 1
PAYOFF_A = cu(200)
PAYOFF_B = cu(180)
PAYOFF_C = cu(120)
PAYOFF_D = cu(0)
class Subsession(BaseSubsession):
def creating_session(self):
players = self.get_players()
# Ensure there is an even number of players to form groups of 2
if len(players) % 2 != 0:
raise ValueError("Number of players is not even. Cannot form groups of 2.")
group_matrix = []
# Shuffle the list of players to randomize the groups
random.shuffle(players)
# Create two groups of two members each
for i in range(0, len(players), C.PLAYERS_PER_GROUP):
group_matrix.append(players[i:i + C.PLAYERS_PER_GROUP])
# Set the new group matrix
self.set_group_matrix(group_matrix)
# Assign a group ID to each player for identification
for group in self.get_groups():
for player in group.get_players():
player.participant.vars['group_id'] = group.id
class Group(BaseGroup):
pass
class Player(BasePlayer):
payment = models.IntegerField(initial=100)
is_bid_winner = models.BooleanField(initial=False)
selected_bid = models.IntegerField(min=0, max=100)
final_euro_amount = models.FloatField(initial=4.00)
cooperate = models.BooleanField(
choices=[[True, 'Cooperate'], [False, 'Defect']],
doc="""This player's decision""",
widget=widgets.RadioSelect,
)
q1 = models.StringField(
choices=[['True', 'True'], ['False', 'False']],
label='Question 1: In the BDM mechanism, if my bid is lower than the randomly chosen price, I will still receive the advice but will not have to pay for it.',
widget=widgets.RadioSelectHorizontal,
)
q2 = models.StringField(
choices=[['True', 'True'], ['False', 'False']],
label='Question 2: In the Prisoner Dilemma game, if both players defect, they will receive a smaller punishment than if they both cooperate.',
widget=widgets.RadioSelectHorizontal,
)
q3 = models.StringField(
choices=[['You get a small punishment, and the other gets a reward', 'You get a small punishment, and the other gets a reward'],
['Both get a moderate punishment','Both get a moderate punishment'],
['You get a heavy punishment, and the other gets a reward','You get a heavy punishment, and the other gets a reward'],
['Both get a small punishment','Both get a small punishment'],],
label='Question 3: In the Prisoners Dilemma, what happens if you cooperate and the other participant defects?',
)
q4 = models.StringField(
choices=[['50 ECU', '50 ECU'], ['100 ECU', '100 ECU'], ['150 ECU', '150 ECU'], ['200 ECU', '200 ECU']],
label='Question 4: What is the maximum amount you can bid for the advice in the BDM mechanism?',
widget=widgets.RadioSelectHorizontal,
)
bid = models.IntegerField(label='What is bid for the Advice?', min=0, max=100)
educational_level = models.StringField(
choices=[['Bachelors Degree', 'Bachelors Degree'], ['Masters Degree', 'Masters Degree'], ['Doctorate Degree', 'Doctorate Degree'], ['Other', 'Other'],],
label='What is your current education program type?',
)
age = models.IntegerField(label='What is your age?', min=13, max=125)
gender = models.StringField(
choices=[['Male', 'Male'], ['Female', 'Female'], ['Other', 'Other'],
['Prefer Not To Say', 'Prefer Not To Say']],
label='What is your Gender?',
)
knowledge = models.StringField(
choices=[
['1', 'Strongly disagree'],
['2', 'Disagree'],
['3', 'Neutral'],
['4', 'Agree'],
['5', 'Strongly agree']
],
label='I was well aware of the game and its rules before starting the experiment.',
widget=widgets.RadioSelectHorizontal,
)
influenced = models.StringField(
choices=[
['1', 'Strongly disagree'],
['2', 'Disagree'],
['3', 'Neutral'],
['4', 'Agree'],
['5', 'Strongly agree']
],
label='Without the advice, my decision would have probably been different. (Select Neutral, in case you did not get the advice)',
widget=widgets.RadioSelectHorizontal,
)
feedback = models.StringField(
choices=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
label='How do you see yourself: are you generally a person who is fully prepared to take risks or do you try to avoid taking risks? Please tick a box on the scale, where the value 0 means “not at all willing to take risks” and the value 10 means “very willing to take risks”',
widget=widgets.RadioSelectHorizontal,
)
# FUNCTIONS
def set_payoffs(group: Group):
for p in group.get_players():
set_payoff(p)
def decide_bid_winner(group: Group):
players = group.get_players()
the_selected_bid = random.randint(1, 100)
for p in players:
p.is_bid_winner = True if p.bid >= the_selected_bid else False
p.selected_bid = the_selected_bid
if p.is_bid_winner == True:
p.payment -= the_selected_bid
def other_player(player: Player):
return player.get_others_in_group()[0]
def set_payoff(player: Player):
payoff_matrix = {
(False, True): C.PAYOFF_A,
(True, True): C.PAYOFF_B,
(False, False): C.PAYOFF_C,
(True, False): C.PAYOFF_D,
}
other = other_player(player)
player.payoff = payoff_matrix[(player.cooperate, other.cooperate)]
player.payment += int(player.payoff)
player.final_euro_amount += (player.payment/100)*1.25
# PAGES
class Introduction_p(Page):
pass
class Introduction_bdm(Page):
@staticmethod
def vars_for_template(player: Player):
if player.id_in_group % 2 == 0:
return {'custom_text': 'a human advice from an expert economics professor'}
else:
return {'custom_text': 'an AI advice generated by ChatGPT'}
class Evaluation(Page):
form_model = 'player'
form_fields = ['q1','q2','q3','q4']
def error_message(self, values):
# Custom validation logic goes here
error_messages = []
# Check if answers are correct
if values['q1'] != 'False':
error_messages.append("Answer to Question 1 is incorrect.")
if values['q2'] != 'True':
error_messages.append("Answer to Question 2 is incorrect.")
if values['q3'] != 'You get a heavy punishment, and the other gets a reward':
error_messages.append("Answer to Question 3 is incorrect.")
if values['q4'] != '100 ECU':
error_messages.append("Answer to Question 4 is incorrect.")
# Display retry warning if any answers are incorrect
if error_messages:
return '\n'.join(error_messages)
class Bidding(Page):
form_model = 'player'
form_fields = ['bid']
@staticmethod
def vars_for_template(player: Player):
if player.id_in_group % 2 == 0:
return {'custom_text': 'a human advice from an expert economics professor'}
else:
return {'custom_text': 'an AI advice generated by ChatGPT'}
class Decision(Page):
form_model = 'player'
form_fields = ['cooperate']
@staticmethod
def vars_for_template(player: Player):
if player.id_in_group % 2 == 0:
return {
'custom_text': 'Human Advice for Playing Prisoner\'s Dilemma Game:
In a single-round Prisoner\'s Dilemma game, where you must make a decision without knowledge of your opponent\'s choice, I would advise you to choose “defect” instead of “cooperate”.
- Defect is a dominant strategy in this game, meaning that it yields always a higher payoff than cooperate, irrespective of what the other player chooses. Empirical evidence from prisoner’s dilemmas indicate that a majority of people (around 80%) indeed chooses their dominant strategy.
- However, not all people choose defect and there is empirical evidence that the likelihood that people choose “cooperate” increases with the attractiveness of the payoff that can be achieved if both players choose cooperate. For example, if the payoff when both cooperate is 2.5 times the size of the payoff if both defect, around 50% of people cooperate. However, if the payoff from both cooperating is not at least double the payoff from both defecting, I advise you to stick to the dominant strategy “defect” because it makes it more likely that you maximize your payoff in this game.
'}
else:
return {'custom_text': 'AI Advice for Playing Prisoner\'s Dilemma Game:
In a single-round Prisoner\'s Dilemma game, where you must make a decision without knowledge of your opponent\'s choice, it is rational to betray. The reasoning behind this decision is based on the inherent risk of betrayal being the dominant strategy.
- Dominant Strategy: In a one-shot game with no possibility of retaliation, betraying is the dominant strategy. Regardless of what your opponent chooses, betraying ensures the best possible outcome for you. If they cooperate, you get a better payoff by betraying; if they betray, betraying avoids the worst possible outcome.
- Risk Mitigation: Since it\'s a single-round game, there\'s no chance for future cooperation or retaliation. Betraying minimizes the risk of being exploited by your opponent, as there is no opportunity for them to reciprocate cooperation in future rounds.
'}
class ResultsWaitPage(WaitPage):
after_all_players_arrive = set_payoffs
class ResultsWaitPageBDM(WaitPage):
after_all_players_arrive = decide_bid_winner
class Results(Page):
@staticmethod
def vars_for_template(player: Player):
opponent = other_player(player)
return dict(
opponent=opponent,
same_choice=player.cooperate == opponent.cooperate,
my_decision=player.field_display('cooperate'),
opponent_decision=opponent.field_display('cooperate'),
)
class Questions(Page):
form_model = 'player'
form_fields = ['educational_level', 'age', 'gender', 'knowledge', 'influenced', 'feedback']
class ThankYou(Page):
form_model = 'player'
class payment(Page):
pass
page_sequence = [Introduction_p, payment, Introduction_bdm, Evaluation, Bidding, ResultsWaitPageBDM, Decision, ResultsWaitPage, Results, Questions, ThankYou]