A potential disadvantage of this method, however, is that it may reduce the impact of emotions: C may, for example, experience stronger emotions when reacting to an actual violation of a fairness norm than when contemplating what he would do in case of such a violation. It is, however, an open question whether the strategy method actually leads to different response probabilities than when subjects respond only to others' actual choices.

QUESTION: Whether the strategy method actually shifts response probabilities remains empirically unsettled — worth checking for experimental evidence.

Ernst Fehr, Third-Party Punishment and …, loc. 24