Previous research indicates that infant-directed speech (IDS) is usually slower than adult-directed speech (ADS) and mothers prefer placing a focused word in isolation or utterance-final position... Show morePrevious research indicates that infant-directed speech (IDS) is usually slower than adult-directed speech (ADS) and mothers prefer placing a focused word in isolation or utterance-final position in (English) IDS, which may benefit word learning. This study investigated the speaking rate and word position of IDS in two typologically-distinct languages: Dutch and Mandarin Chinese. We used a storybook-telling task to elicit semi-spontaneous ADS and IDS. The storybook contained target words that were familiar or unfamiliar to children. For each language, we asked: (1) whether IDS was slower than ADS; (2) whether mothers slowed down to highlight unfamiliar words; (3) whether the speaking rate of IDS changed between 18 and 24 months; and (4) whether mothers preferred placing unfamiliar words in isolation or utterance-final position in IDS. Results suggest that Dutch IDS, but not Mandarin Chinese IDS, was slower than ADS. Also, only Dutch mothers slowed down specifically when introducing unfamiliar words in IDS. In both languages, mothers placed target words in isolation (but not in utterance-final position) more frequently in IDS. These results suggest that the temporal modifications in IDS may vary across languages. Thus, language-specificity of IDS and its implications for language acquisition should be considered in future research. Show less
This study investigates the pitch properties of infant-directed speech (IDS) specific to word-learning contexts in which mothers introduce unfamiliar words to children. Using a semi-spontaneous... Show moreThis study investigates the pitch properties of infant-directed speech (IDS) specific to word-learning contexts in which mothers introduce unfamiliar words to children. Using a semi-spontaneous story-book telling task, we examined (1) whether mothers made distinctions between unfamiliar and familiar words with pitch in IDS compared to adult-directed speech (ADS); (2) whether pitch properties change when mothers address children from 18 to 24 months; and (3) how Mandarin Chinese and Dutch IDS differ in their pitch properties in word-learning contexts. Results show that the mean pitch of Mandarin Chinese IDS was already ADS-like when children were 24 months, but Dutch IDS remained exaggerated in pitch at the same age. Crucially, Mandarin Chinese mothers used a higher pitch and a larger pitch range in IDS when introducing unfamiliar words, while Dutch mothers used a higher pitch specifically for familiar words. These findings contribute to the language-specificity of prosodic input in early lexical development. Show less
Tonal information is essential to early word learning in tone languages. Although numerous studies have investigated the intonational and segmental properties of infant-directed speech (IDS), only... Show moreTonal information is essential to early word learning in tone languages. Although numerous studies have investigated the intonational and segmental properties of infant-directed speech (IDS), only a few studies have explored the properties of lexical tones in IDS. These studies mostly focused on the first year of life; thus little is known about how lexical tones in IDS change as children’s vocabulary acquisition accelerates in the second year (Bloom 2001; Goldfield and Reznick 1990). The present study examines whether Mandarin Chinese mothers hyperarticulate lexical tones in IDS addressing 18-month-old and 24-month-old children—at which age children are learning words at a rapid speed—versus adult-directed speech (ADS). Thirty-nine Mandarin Chinese–speaking mothers were tested in a semi-spontaneous picture-book-reading task, in which they told the same story to their child (IDS condition) and to an adult (ADS condition). Results for the F0 measurements (minimum F0, maximum F0, and F0 range) of tone in the speech data revealed a continuum of differences among IDS addressing 18-month-olds, IDS addressing 24-month-olds, and ADS. Lexical tones in IDS addressing 18-month-old children had a higher minimum F0, higher maximum F0, and larger pitch range than lexical tones in ADS. Lexical tones in IDS addressing 24-month-old children showed more similarity to ADS tones with respect to pitch height: there were no differences in minimum F0 and maximum F0 between ADS and IDS. However, F0 range was still larger. These results suggest that lexical tones are generally hyperarticulated in Mandarin Chinese IDS addressing 18- and 24- month-old children despite the change in pitch level over time. Mandarin Chinese mothers may hyperarticulate lexical tones in IDS when talking to toddlers and potentially facilitate tone acquisition and word learning. Show less
