To explain the phenomenon that certain English verbs resist passivization, Pinker proposed a semantic constraint on the passive in the adult grammar: The greater the extent to which a verb denotes an action where a patient is affected or acted upon, the greater the extent to which it is compatible with the passive. However, a number of comprehension and production priming studies have cast doubt upon this claim, finding no difference between highly affecting agent-patient/theme-experiencer passives and non-actional experiencer theme passives. (...) The present study provides evidence that a semantic constraint is psychologically real, and is readily observed when more fine-grained independent and dependent measures are used. We conclude that a semantic constraint on the passive must be incorporated into accounts of the adult grammar. (shrink)