The use of the domestic dog (Canis familiaris) as a comparative model for speech perception
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Animals have long been used as comparative models for adult human speech perception. However, few animal models have been used to explore developmental speech perception questions. This dissertation encourages the use of domestic dogs as a behavioral model for speech perception processes. Specifically, dog models are suggested for questions about 1) the role and function of underlying processes responsible for different aspects of speech perception, and 2) the effect of language experience on speech perception processes.
Chapters 2, 3, and 4 examined the contributions of auditory, attention, and linguistic processing skills to infants’ difficulties understanding speech in noise. It is not known why infants have more difficulties perceiving speech in noise, especially single-talker noise, than adults. Understanding speech in noise relies on infants’ auditory, attention, and linguistic processes. It is methodologically difficult to isolate these systems’ contributions when testing infants. To tease apart these systems, I compared dogs’ name recognition in nine- and single-talker background noise to that of infants. These studies suggest that attentional processes play a large role in infants’ difficulties in understanding speech in noise.
Chapter 5 explored the reasons behind infants’ shift from a preference for vowel information (vowel bias) to consonant information (consonant bias) in word identification. This shift may occur due to language exposure, or possessing a particular lexicon size and structure. To better understand the linguistic exposure necessary for consonant bias development, I tested dogs, who have long-term linguistic exposure and a minimal vocabulary. Dogs demonstrated a vowel bias rather than a consonant bias; this suggests that a small lexicon and regular linguistic exposure, plus mature auditory processing, do not lead to consonant bias emergence.
Overall, these chapters suggest that dog models can be useful for broad questions about systems underlying speech perception and about the role of language exposure in the development of certain speech perception processes. However, the studies faced limitations due to a lack of knowledge about dogs’ underlying cognitive systems and linguistic exposure. More fundamental research is necessary to characterize dogs’ linguistic exposure and to understand their auditory, attentional, and linguistic processes to ask more specific comparative research questions.