The emergence of labial harmony in Old Hungarian

Hungarian displays both backness harmony (inherited from Proto-Uralic) and labial harmony, the latter developing in Old Hungarian. This paper sets out to explain the fact that the emergence of labial harmony, i.e., the progressive spreading of the feature [labial] in Late Old Hungarian results from an apparent change in the earlier regressive direction of spreading for the same feature. The question addressed here is what caused the change in the direction of the spreading. The hypothesis advanced is that Early Old Hungarian regressive spreading of labiality did not affect lexical cues, since [labial] was a redundant feature; the spreading was motivated by coarticulatory mechanisms. However, as [labial] became a robust contrastive feature in the Old Hungarian period, it aligned with backness in its spreading direction to enhance lexical recognisability. The argument also implies that while labial harmony owes its origin to a pattern rooted in coarticulatory mechanisms, in its mature form it acquired a superimposed perceptual motivation.