Preferences can be expressed as wishes, constraints or both. Generally, wishes and constraints do not complement each other. A different reasoning principle is applied to rank-order the set of options depending on whether preferences refer to wishes or constraints. Consequently, these two types of preferences have been characterized by two separate sets of postulates offering a normative view of the preferences. This paper provides a complementary study. In particular an empirical analysis has been conducted in order to assess human endorsement of the normative view of wishes and constraints. Results showed that single postulates are highly endorsed by humans. However the latter showed more or less strong endorsement w.r.t. patterns of postulates. US laypersons and French participants in the experiment showed different behaviors.