Actions speak louder than words: signing and speech intelligibility in adults with Down syndrome

Abstract

Previous studies into the use of key-word signing with people with a learning disability have concentrated on its contribution to the development of speech and language. The few studies focusing on its relationship to actual speech production and intelligibility were based on taught target words or phrases. This study, which was of quasi-experimental design, looked at whether reported improvements in intelligibility were supported in spontaneous speech production. Communication samples were collected by video recording `good' and `poor' speakers under `high' and `low' signing conditions. `Skilled' and `naive' raters assigned intelligibility ratings under `seen' and `unseen' conditions. It was predicted that speech from the `high' signing condition would be rated more highly than that from the `low' signing condition. This was supported. The iconicity of signs was shown to have a positive effect for `naive' raters when rating the `poor' speakers, which may counter previous arguments that the general public would be unable to understand communication attempts by people using key-word signing.