The changing status of 'filler syllables' on the way to grammatical morphemes

The appearance of 'filler syllables' (called here PAEs, for Prefixed Additi onal Elements) in the late single-word period is analysed in relation to th e emergence of grammatical morphemes, by confronting data from the longitud inal study of one child acquiring French, video-recorded between 1; 3.2 and 2; 2.6, with four hypotheses making different claims about the kind of lan guage knowledge underlying their production: the DEVICES TO LENGTHEN SINGLE -WORD UTTERANCES, the SYNTACTIC SLOTS, the SELECTIVITY OF OCCURRENCE, and t he ORGANIZATION OF SURFACE REGULARITIES hypotheses. The pattern of results concerning the first two to three months' production of PAEs points to the existence of a premorphological period in which PAEs result from the organi zation of phonoprosodic regularities of the language rather than being cons trained by structural rules relative to syntactic slots or to the class of the word they precede. This premorphological period is followed by a protom orphological one in which incipient properties of grammatical morphemes and of word classes start to appear at the same time.