Unlike English, which uses prepositional words to indicate spatial connections, American Sign Language (ASL) relies on the placement of the hands to do so. We used event-related fMRI to look at how well people understood ASL and acoustic English versions of phrases that were either perspective-dependent (PD; left/right) or perspective-independent (PI; in/on) (sentence-picture matching task). Consistent with a prior study involving written English, PD sentences activated the superior parietal lobule (SPL) on both sides of the brain, unlike non-spatial control phrases. According to the examination of ASL-English conjunctions, SPL activity is symmetrical for PD sentences but left lateralized for PI phrases. When comparing PD and PI expressions head-on, we found that SPL activation was higher for PD expressions of ASL but not PI expressions. SPL activation is higher for ASL PD expressions because of the mental shift needed to understand the signer's perspective on where things are in the signing environment. The data imply that understanding spatial language in ASL and English is supported by a combination of overlapping and unique brain areas.

English, fMRI, Sign language, Deaf, Spatial language