Tragedy of Commons
An In-Class Experiment
By: Mostafa Beshkar
This experiment demonstrates the behavior of a group of people who have access to a free and common resource. In this experiment, 5 individuals can fish from a pool that initially has a stock of 64 fish. In each period, each person has enough time to catch at most 8 fish (if available). The resource is renewable, such that a fish in the pool can produce a new fish each period. However, the maximum number of fish that can live in the pool is 64 and the rest will die.
Instruction:
1) Download the excel file of the experiment from here.
2) Ask for 5 volunteers from your students to take part in the experiment, and write their names in the fist column.
3) Run the experiment for at least 8 rounds (or until there is no fish in the pool!!)
4) In each period, students should write down the number of fish that they want to catch (max 8). Then ask them to announce their decision and enter it into the appropriate cell on the spreadsheet.
The stock of fish will be automatically updated as you enter the announced numbers. If the total attempted harvest is more than the total available stock, the stock is distributed among the students proportionate to their attempt.
5) At the end, you should reward the students for the number of fish that they caugth.
Now run a new round of the experiment, but let the students discuss their decision before announcing it. This should give them some insight about sustaining cooperation through repeated interactions.