Input-output (I-O) modality compatibility refers to the similarity of stimulus modality and modality of response-related sensory consequences. A previous study found higher switch costs in task switching in I-O modality incompatible tasks (auditory-manual and visual-vocal) than in I-O modality compatible tasks (auditory-vocal and visual-manual). However, these tasks had spatially compatible S-R mappings, which implied dimensional overlap (DO). DO may have led to automatic activation of the corresponding compatible responses in the incorrect response modality, thus increasing interference effects. The present study was aimed to examine the influence of DO on I-O modality compatibility effects. In two experiments, we found that I-O modality compatibility affects task switching even in tasks without DO, which even tended to result in further increased modality influences. This finding suggests that I-O modality mappings affect response selection by affecting between-task cross-talk not on the level of specific response codes but on the level of modality-specific processing pathways.