Bernier, Dana2020-01-292020-01-292020-01-292020-01-15http://hdl.handle.net/10012/15598Young language learners acquire their first language(s) from the speech they are exposed to in their environment. For at least some children (e.g., those in daycare), this environmental speech includes a large quantity of speech from other children. Yet, we know little about how young learners process this type of speech and its status as a source of input. This dissertation will examine these questions by assessing toddlers’ processing of older children’s speech, both in general and as a function of their experience with other children. Chapter 2 begins by showing that 21- to 23-month-olds processed a 7-year-old speaker’s productions of familiar words as well as those of an adult, and with the same level of sensitivity to phonetic detail previously shown for adult speakers. This is followed in Chapter 3 with 21- to 23-month-olds showing differential treatment of mispronunciations of familiar words depending on the type of mispronunciation (common to child speech or rare), the speaker that produced them (an adult or a 6-year-old), and the specific contrast involved (/w/-/ɹ/ or /t/-/ʧ/). Finally, Chapter 4 shows that by 3 years at least some children may have the expectation that a 5-year-old would mispronounce /ɹ/ as [w] (e.g., rainbow as wainbow), but that an adult would not. Effects of experience were assessed across all experiments. When effects of experience with other children were found, they were small. Overall, these findings demonstrate that child speech may represent useful input for young language learners.enchild speechspoken word processingphonetic sensitivityperceptual asymmetriestype of childhood mispronunciationdisambiguation responselanguage environmentstoddlersSpeech perception in childrenPsycholinguisticsLanguage acquisitionInterpersonal communication in childrenSpeech errorsDoctoral Thesis