Information sharing is frequently promoted as a mean to improve the supply chain performance. This work shows the results of behavioral experiments, in which the participants share private information in order to influence the contract terms in a Just-in-Time environment. It is shown that the impact of information sharing is ambiguous, and dependent on several factors, such as contract flexibility and complexity or the interacting behavioral types. The experimental results form the basis for a behavioral principal-agent model that gives valuable insights on how the interaction of trust, trustworthiness and the information sharing strategy impacts the supply chain performance.