Theories of perceptual development differ in the extent to which initial perceptual sensitivities and language experience influence infants’ perception of speech. Extant research focuses largely on infants’ ability to distinguish native and non-native speech sound categories. In two experiments, we investigated infants’ developing perception of relationships between similar sounds, i.e., vowel harmony patterns, to inform on this debate. In Experient 1, we show that language experience is not necessary to detect vowel harmony; 4-month-olds without harmony experience can differentiate harmonic and disharmonic nonce words. We argue that this is evidence of a universal perceptual grouping bias, wherein similar sounds are perceived as being grouped together despite their objective temporal distance. Then in Experiment 2, we show that without relevant language experience, this initial sensitivity to vowel harmony declines by 8-months as infants begin to tune into the sound patterns of their native language. We argue that our results, combined with previous findings, are best explained under perceptual attunement theories. When not reinforced by their language input, infants show a decline in their sensitivity to vowel harmony; but an initial sensitivity to relationships between similar vowels may facilitate infants’ learning of vowel harmony patterns in their native language.

Two types of discontinuous morphemes are thought to be the basic building blocks of words in Semitic languages: roots and templates. However, the role of these morphemes in lexical access and representation is debated. Priming experiments, where reaction times to target words are predicted to be faster when preceded by morphologically-related primes compared to unrelated control primes, provide conflicting evidence bearing on this debate. We used meta-analysis to synthesise the findings from 229 priming experiments on 4710 unique Semitic speakers. With Bayesian modelling of the aggregate effect sizes, we found credible root and template priming in both Arabic and Hebrew, in nouns as well as verbs. Our results show that root priming effects can be distinguished from the effects of overlap in form and meaning. However, more experiments are needed to determine if template priming effects can be distinguished from overlap in form and morphosyntactic function.

This thesis investigates the verbal morphology of Lachirioag Zapotec, a Northern Zapotec language from the town of San Cristóbal Lachirioag in Oaxaca, Mexico. There are two parts of the verbal morphology that are the focus of this thesis, the TAM prefixes and the argument enclitics. There are two kinds of TAM prefix: primary prefixes, which are obligatory, and secondary prefixes, which are not. The first part of the thesis centers around the primary prefixes and their use, with a focus on the allomorphy exhibited by the perfective and irrealis prefixes. The second part of the thesis discusses the secondary prefixes and the information that they convey. Finally, the third part focuses on the argument enclitics and plural marker, specifically on their distribution and cooccurrence restrictions.