Handshape is the hardest path in Portuguese Sign Language acquisition: Towards a universal modality constraint

Sign languages have only been acknowledged as true languages in the second half of the 20th century. Studies on their ontogenesis are recent and include mostly comparative approaches to spoken language and sign language acquisition. Studies on sign language acquisition show that of the manual phonological parameters, handshape is the one which is acquired last. This study reports the findings of a first pilot study on Portuguese Sign Language (Língua Gestual Portuguesa — LGP) acquisition, focusing on a Deaf child from 10 months until 24 months of age, and it confirms the pattern previously described for other sign languages. We discuss possible reasons why handshape is harder to acquire, which relate to neuromotor development and perceptual issues, and we suggest that auditory deprivation might delay the acquisition of fine motor skills.