Each participant completed two task scans: a deception task run and a control task run. In both games, the participant (the sender) is presented with two potential allocations of monetary gains (A and B) for themselves and a counterpart (the receiver). On each trial, one allocation provides a larger payoff to the sender, while the other provides a larger payoff to the receiver. Critically, in the deception task, senders must choose between two messages that are verifiably truthful or false (e.g., “Option A will earn you more money than B”). In contrast, in the control task, the senders’ messages do not have a truth value (e.g., “I prefer that you choose option A”).