  An uninformed sender publicly commits to an informative experiment about an
uncertain state, privately observes its outcome, and sends a cheap-talk message
to a receiver. We provide an algorithm valid for arbitrary state-dependent
preferences that will determine the sender's optimal experiment and his
equilibrium payoff under binary state space. We give sufficient conditions for
informative information transmission. These conditions depend more on marginal
incentives -- how payoffs vary with the state -- than on the alignment of
sender's and receiver's rankings over actions within a state. The algorithm can
be easily modified to study the canonical cheap talk game with a perfectly
informed sender.
