Ambiguity resolution requires high-level interpretation processes, at least some of which are subserved by theinferior frontal gyrus (IFG), a region that is susceptible to modulation by task demands. This fMRI study investigates the extentto which ambiguity-related activation in IFG is modulated by the specific cognitive-linguistic demands posed by the modality inwhich a sentence is presented. In the present study, ambiguous sentences and matched unambiguous sentences were presentedin three conditions: listening, reading, and rapid serial visual presentation (RSVP). The RSVP modality elicited strongerambiguity-related haemodynamic responses than the other two modalities, particularly in left anterior IFG. This indicatesthat the RSVP modality cannot be used as a simple substitute for natural reading without taking into account the additionalprocessing resources it requires.