title: Boundary alignment enables 11-month-olds to segment vowel initial words from speech.
abstract: Past research has indicated that English-learning infants begin segmenting words from speech by 7-5 months of age (Jusczyk & Aslin, 1995). More recent work has demonstrated, however, that 7-5-month-olds' segmentation abilities are severely limited. For example, the ability to segment vowel-initial words from speech reportedly does not appear until 13.5 to 16 months of age (Mattys & Jusczyk, 2001; Nazzi, Dilley, Jusczyk, Shattuck-Hufnagel & Jusczyk, 2005). In this paper, we report on three experiments using the Headturn Preference procedure that investigate both phonetic and phonological factors influencing 11-month-olds' segmentation of vowel-initial words from speech. We replicate earlier findings suggesting that infants have difficulty segmenting vowel-initial words from speech. In addition we extend these findings by demonstrating that under certain conditions, infants are capable of segmenting vowel-initial words from speech at a much younger age than earlier studies have reported. Our findings suggest that infants' ability to segment vowel-initial words from speech is tightly constrained by acoustic-phonetic factors such as pitch movement at the onset of vowel-initial words and segmental strengthening. These experiments underscore the complexity of early word segmentation, and highlight the importance of including contextual factors in developmental models of word segmentation.
authors.affiliation: Department of Speech, Language and Hearing Sciences, 500 Oval Drive, Purdue University, West Lafayette, IN 47906, USA. aseidl@purdue.edu
authors.forename: Amanda
authors.initials: A
authors.lastname: Seidl
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Johnson
mesh_terms: D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010700:Phonetics; D013063:Speech Discrimination Tests; D013067:Speech Perception; D014825:Vocabulary