Running Head : Automatic imitation in a strategic context 1 2 3 Automatic imitation in a strategic context : 4 Players of Rock - Paper - Scissors imitate opponents ’ gestures

mirror neuron system 30 31  Cook: conducted experimental sessions; contributed to the data analysis and interpretation; wrote the first draft of the paper. Bird: contributed to the design of the experiment; conducted experimental sessions. Lünser: contributed to the design, data analysis and second draft of the paper. Huck: provided the idea for the study; contributed to the design, data analysis, interpretation and second draft of the paper. Heyes: contributed to the design, data analysis and interpretation; wrote the final draft of the paper. ABSTRACT 32 A compelling body of evidence indicates that observing an action makes the execution of that action 33 more likely. However, it remains unclear whether this so-called 'automatic imitation' is indeed 34 automatic (i.e. reflexive and involuntary) or whether these effects are better characterised as voluntary 35 actions. The present study sought to test the automaticity of automatic imitation by studying whether 36 imitative responding emerges in a strategic context where it reduces payoffs. Participants were 37 required to play Rock-Paper-Scissors, with the aim of achieving as many wins as possible, while 38 either one or both players were blindfolded. While the frequency of draws in the blind-blind condition 39 was precisely that expected at chance, the frequency of draws in the blind-sighted condition was 40 significantly elevated. Specifically, the execution of either a rock or scissors gesture by the blind 41 player was predictive of an imitative response by the sighted player. That automatic imitation emerges 42 in a context where imitation reduces payoffs accords with its 'automatic' description, and implies that 43 these effects are more akin to involuntary reflexes than to voluntary actions. These data represent the 44 first evidence of automatic imitation in a strategic context, and challenge the abstraction from 45 physical aspects of social interaction typical in economic theory and game theory.