The effect of opponent type on human performance in a three-alternative choice task.

•Participants played a Paper Scissors Rock game against a computer or a fictitious human opponent.•Sensitivity to the relative reinforcer rate was higher for those in the “computer” condition than the “player” condition.•Perceived opponent type can alter the effect of reinforcer contingencies on human choice behaviour.•The generalised matching law was a good descriptor of three-alternative human choice behaviour.