Undifferentiated lingual gestures in children with articulation/phonological disorders.

Previous research using electropalatography (EPG) has shown that a distinctive articulatory characteristic of lingual consonants in the speech of school-age children with articulation/phonological disorders (APD) is a high amount of tongue-palate contact. Consonants produced in this way have been referred to as undifferentiated lingual gestures. This article reviews the EPG literature on undifferentiated gestures with 4 overarching goals: (a) to provide a precise articulatory description of undifferentiated gestures, (b) to estimate the rate of occurrence of undifferentiated gestures in children with APD, (c) to propose an original.interpretation of undifferentiated gestures, and (d) to discuss the significance of the gestures in the light of current theories of APD. Undifferentiated gestures typically occur during productions of lingual consonant targets and are characterized by contact that lacks clear differentiation between the tongue apex, tongue body, and lateral margins of the tongue. The EPG literature reports 17 school-age children with APD, of whom 12 (71%) show evidence of undifferentiated gestures. Standard transcriptions do not reliably detect undifferentiated gestures, which are transcribed as speech errors (e.g., phonological substitutions, phonetic distortions) in some contexts, but are transcribed as correct productions in other contexts. Undifferentiated gestures are interpreted as reflecting a speech motor constraint involving either delayed or deviant control of functionally independent regions of the tongue. The limitations of the current EPG literature are stated, and the need for research into undifferentiated gestures in preschool children is discussed.