The purpose of the present study was to tease apart the paralinguistic from the linguistic aspects of infants' perception of infant-directed (ID) speech. Several studies have shown that infants beginning at a few days after birth discriminate native from nonnative speech and can discriminate specific contours (rising, falling, rising-falling) in ID speech. Some studies have also indicated that infants at 4.5 months of age prefer their own name over other names but at 6 months of age, fail to prefer a sentence with their own name embedded in it. Using a discrimination procedure, the current study investigated whether 6-month-old infants could detect a change in contour and/or a change in words when listening to ID utterances. Results indicated that 6-month-old infants detected both a contour and a word change. From these results, it is argued that as has been shown in other experiments, infants are extremely sensitive to subtle changes in speech. Furthermore, ID speech appears to facilitate infants' ability to discriminate small changes in ID speech (both linguistic and paralinguistic). It is suggested that future studies investigate more discrete changes in speech samples and a replication of this research with adult-directed (AD) speech. / Master of Science

The purpose of the present study was to investigate the role of pitch contours in directing infant attention to adult speech. Several studies have shown that infants from a few days old to 9 months of age prefer infant-directed (ID) over adult-directed (AD) speech. Moreover, 4-month-olds have been shown to prefer pitch contours that simulate ID speech, suggesting that the exaggerated pitch contours are necessary for infant attention. The current study investigated this attentional preference utilizing ID and AD pitch contours in a fixation-based preference procedure. Results from the first experiment failed to show a similar preference for the ID pitch contours. Because a lack of preference could have been due to a failure to discriminate, a habituation study was also conducted. The results from the second experiment showed that 4-month-olds can discriminate the ID and AD pitch contours. From these results, it is argued that the pitch contour may be but one of many possible prosodic characteristics that attract infant attention and this attention may occur only within a language context. It is suggested that future studies investigate ID speech using a more context-dependent procedure, where natural or more complete speech samples are utilized. / Master of Science