Patterns of glide formation in Niger-Congo: an optimality account

A study examined the pattern of formation of glides in a sample of 18 Niger-Congo languages that have substantial glide formation. It is noted first that four basic pattern dualities exist, with language-specific variations, determine by whether or not: (1) glide formation applies to both front and round first vowels or round first vowels only; (2) glide formation applies to both high and mid first vowels or high first vowels only; (3) glide formation may apply when first and second vowel agree in roundness and/or frontness; and (4) coalescence occurs in addition to glide formation. The analysis outlined here attempts to account for the permitted range of variation while explaining the absence of the unattested patterns. A number of common constraints are described and their patterns of occurrence in language types are discussed. It is concluded that although there is considerable cross-linguistic variation in glide formation, the variation is subject to some surprising but seemingly robust restrictions. Both the restrictions and observed variation can be accounted for by the variable ranking of a small number of constraints, some of which deal specifically with glides and glide-plus-vowel sequences, while others are independently needed to account for other phenomena. Contains five references. (MSE)