Influences of Infant-Directed Speech on Early Word Recognition

Abstract

When addressing infants, many adults adopt a particular type of speech, known as infant-directed speech (IDS). IDS is characterized by exaggerated intonation, as well as reduced speech rate, shorter utterance duration, and grammatical simplification. It is commonly asserted that IDS serves in part to facilitate language learning. Although intuitively appealing, direct empirical tests of this claim are surprisingly scarce. Additionally, studies that have examined associations between IDS and language learning have measured learning within a single laboratory session rather than the type of long-term storage of information necessary for word learning. In this study, 7- and 8-month-old infants' long-term memory for words was assessed when words were spoken in IDS and adult-directed speech (ADS). Word recognition over the long term was successful for words introduced in IDS, but not for those introduced in ADS, regardless of the register in which recognition stimuli were produced. Findings are discussed in the context of the influence of particular input styles on emergent word knowledge in prelexical infants.

Notes

¹Although detrimental effects of a lack of IDS exposure have not been demonstrated thus far, two studies have demonstrated that the absence of a listening preference for IDS might signify risk for autism in both infants and children (Kuhl, Coffey-Corina, Padden, & Dawson, 2005; Nadig, Ozonoff, Singh, Young, & Rogers, 2007), suggesting that responsivity to IDS might serve as a marker with which to identify risk for particular clinical syndromes. It should also be noted that there have been related investigations of the effects of maternal depression on child language development, suggesting that the absence of IDS is associated with slower vocabulary development and poorer performance on associative learning tasks (Bettes, 1988; Kaplan, Dungan, & Zinser, 2004; Kaplan, Sliter, & Burgess, 2007).

*p < .0001.

**p < .00001.

*p < .05.

**p < .001.

***p < .0001.

²In previous studies, 30 sec of familiarization was used. However, this criterion was increased to allow infants more exposure to words in light of the time delay instituted between training and test. This modification was invited by pilot study where it resulted in more robust effects in the data collected.