The Miracle Year: From Basic Structure to Social Communication

The Miracle Year: From Basic Structure to Social Communication

Heather Bortfeld (University of Connecticut, USA & Haskins Laboratories, USA), Kathleen Shaw (University of Connecticut, USA) and Nicole Depowski (University of Connecticut, USA)
DOI: 10.4018/978-1-4666-2973-8.ch007
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Abstract

In recent years, a functional perspective on infant communication has emerged whereby infants’ production of vocal sounds is understood not only in terms of the acoustic properties of those sounds, but also in terms of the sounds that regulate and are regulated by social interactions with those hearing them. Here, the authors synthesize findings across several disciplines to characterize this holistic view of infant language learning. The goal is to interpret classic and more recent behavioral findings (e.g., on infants’ preferences) in light of data on pre- and postnatal neurophysiological responses to the environment (e.g., fetal heart rate, cortical blood flow). Language learning is a complex process that takes place at multiple levels across multiple systems; this review is an attempt to embrace this complexity and provide an integrated account of how these systems interact to support language learning.
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Learning About Sound Structure In Utero

Strict interpretations of language development as completely experience driven or completely innately guided have softened in recent years, concomitant with accumulating evidence that changes in the environment have substantial effects on language outcome. Indeed, there is evidence that environmental tuning is at work in utero, thus demonstrating that, by the time an infant is born, biology and environment have already combined to set the process of language learning in motion.

Research on prenatal infants, while difficult to conduct, has been important to our emerging understanding of how exposure to sound in the womb gives babies a head start with language. The womb acts as a low-pass filter for sounds in the mother’s environment (Gerhardt, et al., 1990). This includes the voices of those around her and her own. Furthermore, where others’ voices vary in intensity depending on where they are relative to the mother, the mother’s own voice is present for the developing fetus at a relatively constant volume and with more clarity than other voices, given the internal nature of the source (e.g., mother’s vocal folds, articulators). This means that, in addition to the external voice, internal bone and membrane conduction supplements the signal, providing infants with a relatively robust and consistent source of speech input. How this signal interacts with the maturation of the infant’s auditory system is important to informing our understanding of what infants have already learned about language when they enter the world.

Using changes in the fetal heart rate as their dependent measure, Lecanuet et al. (1995) obtained some of the first physiological data to suggest that fetal hearing occurs before 28 gestational weeks. In fact, the fetus appears to respond to sound at 22 gestational weeks (Hepper & Shahidullah, 1994) and habituates to repeated sounds around 32 gestational weeks (Morokuma, et al., 2004). Moreover, as infants near term, their sensitivity to more complex auditory stimuli improves, allowing them to perceive variations in music (Kisilevsky, et al., 2004) and to differentiate between familiar and novel rhymes (DeCasper, et al., 1994). Thus, the concept of “experience,” rather than strictly referring to information available to the infant postnatally, implies a currently unknown threshold in prenatal auditory processing as well. Needless to say, this has not simplified theoretical debates about the degree to which nature and nurture come into play in early language development; it has only served to push the focal age for this debate earlier. However, these data represent an important advance in our understanding of the toolkit with which infants enter the world.

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