Switching competitors reduces win-stay but not lose-shift behaviour: The role of outcome-action association strength on reinforcement learning

Predictability is a hallmark of poor-quality decision-making during competition. One source of predictability is the strong association between current outcome and future action, as dictated by the reinforcement learning principles of win-stay and lose-shift. We tested the idea that predictability could be reduced during competition by weakening the associations between outcome and action. To do this, participants completed a competitive zero-sum game in which the opponent from the current trial was either replayed (opponent repeat) thereby strengthening the association, or, replaced (opponent change) by a different competitor thereby weakening the association. We observed that win-stay behaviour was reduced during opponent change trials but lose-shift behaviour remained reliably predictable. Consistent with the group data, the number of individuals who exhibited predictable behaviour following wins decreased for opponent change relative to opponent repeat trials. Our data show that future actions are more under internal control following positive relative to negative outcomes, and that externally breaking the bonds between outcome and action via opponent association also allow us to become less prone to exploitation.