In this task, you are asked to bet on whether a virtual coin flip will come up heads or tails. You start with a 50 cent “bankroll.” You can bet any amount, from 1 cent up to your total bankroll, on the first coin flip. If you win, your bankroll increases by the amount you bet. If you lose, your bankroll decreases by the amount you bet.
As long as you have money in your bankroll, you can keep flipping the coin and betting as many times as you want for up to 12 minutes. Your bonus will be your balance at the end of the task, up to a maximum of $7.50. If your bankroll reaches $7.50, the task will end. If your bankroll hits zero, the task will end and you will not earn a bonus. Otherwise, your bonus will be your bankroll when the 12 minutes expire.
The coin flip is biased to come up heads more often. The chance of coming up heads will be between 55% and 70% on any given flip. Your screen will tell you before you bet on each flip what the chance of heads is.
After the end of the coin toss game, we will ask you to complete a brief survey about your experience with the game. You will need to respond to the survey in order to complete the task.
Here is a tip on how to play: use a strategy called the Kelly rule. The Kelly rule says that the percentage of your bankroll that you put on the coin toss should match your profit margin.
How does that work? If there is a 55% chance of heads and you bet on heads, your margin is 55% to win minus 45% to lose = 10%. You should risk 10% of your bankroll on a heads bet if heads is 55% likely. If heads is 60% likely, you should risk 20% on heads (60% win - 40% lose), and if heads is 70% likely, you should risk 40% on heads (70% win - 30% lose).
You do not have to follow this rule and can play any way you want. The advantages of this rule, however, are 1) you cannot go bankrupt using it, and 2) on average, it grows your money the most effectively over the long run.
Click when you are ready to begin