Morgan Grant edited this page Sep 19, 2017 · 1 revision

Table of Contents

Pure Selector


The pure selector allows users to select one action of n possibilities via a radio button. This selector is ideal for prisoner's dilemma or hawk-dove type matrix games in which the experimenter desires subjects to have choice over strictly pure action options.


  • Y-axis - Subjects choose by using their mouse or up/down arrow-keys from a discrete set of action options indicated by the two radio buttons. The row in the payoff matrix corresponding to the subject's decision is then highlighted light blue, indicating that their payoffs will come from this row. For example, in the figure below this player has selected action "B", (note the radio button is filled and the bottom row is highlighted).
  • X-axis - The action that counterpart subjects select is shown by highlighting the relevant column. This highlighting is updated instantaneously in continuous time, or for the previous subperiod with discrete time. In the figure below the counterpart player has chosen action "a", corresponding to payoffs in the left column of the payout matrix.
  • Current flow payoffs - The intersection of subject actions - the cell that is doubly highlighted - displays current flow payoffs. In the figure below this player is earning 18, while the counterpart player is earning 0.
  • Flow payoff chart - To the right of the payoff matrix and selector, a chart records over time subject's flow payoffs, including the subject's opponent's payoffs. Note that in the payoff chart, the most recent flow payoff for "You" is 18, and the most recent "Other" flow payoff is 0.
  • Time Left - "Seconds left" and "Subperiods Left" are self explanatory. For more details, see the continuous time vs. discrete time discussion.
  • "Previous Earnings", and "Current Earnings" are self-explanatory.
  • Obviously, mixed strategies are not possible with this selector.
Figure - This player chose action "B" for the entire period, and the other player chose "A". The numbers in the grid on the left side of the window refer to the different payouts possible. Bold numbers in the payoff matrix are own payoffs, while the second number, non-bolded, reflects the counterpart player's potential payoffs. The subject picks either the top or bottom radio button (making the subject the 'row player') while the subject's opponent plays either in the left or right columns (making that player the 'column player'). This use of the pure selector is for a Matrix2x2 game, where each cell has values set ahead of time in the configuration file. The pure selector forces the players to play either A or B, and will highlight the choice that player made. The square that is highlighted by both the row and column indicates which payoff the player will receive. The player receives the amount listed on the left of the pair of numbers in the square.

The below table is an example of the config file pure. The actual file has the items separated by commas, which is why the config files are CSV (comma separated value) files.

period paid length subperiods percentChangePerSecond groupSize payoffFunction name min max Aa Ab Ba Bb selector
1 TRUE 60 0 NaN 1 matrix2x2 first 0 17 10 0 18 4 pure
2 TRUE 60 1 NaN 1 matrix2x2 first 0 17 10 0 18 4 pure
3 TRUE 60 6 NaN 1 matrix2x2 first 0 17 10 0 18 4 pure

Compatible Payoff Functions

The payoff function most strongly related to the pure strategy selector is matrix2x2, which is used in Prisoner's Dilemma and Hawk Dove.

For more information about selector/payoff function compatibility go here

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