Handshaking promotes deal-making by signaling cooperative intent.

We examine how a simple handshake-a gesture that often occurs at the outset of social interactions-can influence deal-making. Because handshakes are social rituals, they are imbued with meaning beyond their physical features. We propose that during mixed-motive interactions, a handshake is viewed as a signal of cooperative intent, increasing people's cooperative behavior and affecting deal-making outcomes. In Studies 1a and 1b, pairs who chose...