Witkin, G.A., Morere, D.A. & Geer, L.D. (2013). Establishment of a phonemic clustering system for American Sign Language. Sign Language Studies, 14(1), pp. 21-38.
Executive functioning, the self-regulatory or control system that governs all cognitive, behavioral, and emotional activity, may be measured by means of a variety of psychological and neuropsychological tests, including tests of verbal fluency A subset of these tasks, phonemic fluency, requires a person to generate words based on a letter cue (e.g., words that begin with the letter f). However, such tests are designed for users of spoken language. This article reports on the use of a measure of verbal fluency for American Sign Language (ASL) for which, in addition to the traditional score based on the total number of words produced during the task, an analysis of ASL-based "clusters" (related signs produced in succession) and "switches" (transitions from one cluster to another) was developed. Previous research with standard verbal fluency tasks has suggested that cluster and switching analysis reflects mental flexibility and cognitive search skills. A system for analyzing phonemic clusters in ASL is described, and its application is demonstrated using a case example.