A simple audio-visual two-alternative forced-choice task was conducted to examine processing differences between the modal verbs should and must. Unambiguous propositions were either agreed with or disagreed with, and participants’ eye movements were monitored as they heard and read the sentence. Reaction times reveal no differences in processing. However, closer time course analyses revealed a divergence in fixations to the target for should. These results suggest two mental models are simultaneously activated, entailing both agreement and disagreement with the statement in question.