  We conducted an experiment where participants played a perfect-information
game against a computer, which was programmed to deviate often from its
backward induction strategy right at the beginning of the game. Participants
knew that in each game, the computer was nevertheless optimizing against some
belief about the participant's future strategy.
  It turned out that in the aggregate, participants were likely to respond in a
way which is optimal with respect to their best-rationalization extensive form
rationalizability conjecture - namely the conjecture that the computer is after
a larger prize than the one it has foregone, even when this necessarily meant
that the computer has attributed future irrationality to the participant when
the computer made the first move in the game. Thus, it appeared that
participants applied forward induction. However, there exist alternative
explanations for the choices of most participants; for example, choices could
be based on the extent of risk aversion that participants attributed to the
computer in the remainder of the game, rather than to the sunk outside option
that the computer has already foregone at the beginning of the game. For this
reason, the results of the experiment do not yet provide conclusive evidence
for Forward Induction reasoning on the part of the participants.
