In Homer’s Odyssey, Ulysses binds his hands to the mast and has his crew fill their ears with wax to prevent them from hearing the Siren’s call. In this way, he could not react to the call, and they could not hear it. Ulysses contracts are when we implement a barrier-reducing (e.g. keeping healthy snacks around to encourage healthy eating) or barrier-inducing (e.g. avoiding a fast food place) to shape future behavior1.