Each student is matched with another over a number of rounds. In each round, each is presented with the two-by-two matrix and must choose between Stag or Hare. Actions and payoffs are revealed after each round.
Stag hunt is the classic two-person game where the common good requires collective action, but contributing entails payoff risk. Stag is risky in that it only gives a high payoff if the other student chooses it as well. Hare guarantees a medium payoff. Stag-Stag is a Nash equilibrium that is both efficient and Pareto Optimal, but exposes players to risk. Hare-Hare is an inefficient Nash equilibrium, but is safe.
Stag Hunt is an instructive counterpoint to the Prisoner's Dilemma. In both cases, there is a tension between what is good for the individual and what is good for the group. Whereas in the Prisoner's Dilemma the action leading to the social optimum is dominated, in the Stag Hunt cooperation is not dominated but is risky.
Players may fail to coordinate on the efficient equilibrium, even if preferred by all to the inefficient equilibrium, if choosing the action leading to the social optimum exposes the player to strategic risk.
Coordination failure is likely most common in the one-shot interaction. Both communication and repeat interaction will increase coordination on the efficient and Pareto Optimal equilibrium.
Especially when played once without communication (change Minimum Rounds to 1), many groups will fail to coordinate on Stag-Stag.
Note: In the mixed-strategy equilibrium, stag is chosen with 60% probability. It would not be surprising if this matches the population average of the one-shot game.
Five is the default number of rounds, which should be sufficient to see an increase in coordination. Checking Allow Chat will result in nearly universal coordination on the efficient equilibrium.
The results screen presents a table and a chart, each focusing on the likelihood of each action.
The table (Figure 2) indicates the percentage of students choosing each action for each round.
The chart (Figure 3) presents this information in a slightly different way. It shows the incidence of the three outcomes for each round: both played Hare, both played Stag, and one played Hare while the other played Stag. It is likely that groups playing Stag/Hare in early rounds will quickly coordinate on one of the two Nash equilibria.
Note that the chart has dynamic elements. Click the checkboxes in the legend to hide a particular category. Also, hovering the cursor over a label in the legend highlights the corresponding bars in the chart.