Language is the standard by which higher intellectual processes are revealed. It is important means of social communication and is one of the exceptional systems of habits which distinguish man from the animals. Differences in language account for many of the distinct contrasts between peoples, and to its deficiency may be attributed the differences between intellectual development. As preverbal infant it is important for caregivers to know how to acquire the fundamental aspects of language more efficiently. "Motherese" or child-directed speech (CDS) is a pattern of speech which is used for communication with preverbal children. Child-directed speech found to draw children' attention more decently due to distinctive characteristics (Brand, Baldwin & Ashburn, 2002; Bohannon & Marquis, 1977; Fernald & Mazzie, 1991; Greiser & Kuhl, 1988; Hoff-Ginsberg, 1986; Masataka, 1998; O'Neill, Bard, Linnel, & Fluck, 2005; Rowe, Pan & Coker, 2004; Sokol, Webster, Thompson & Stevens, 2005; Tamis-LeMonda & Bornstein, 1994). In this study we will investigate the aspects of child-directed speech and the contribution of it to infants' language development.
First, to describe CDS it is important to underline that for occurrence of CDS an infants' or young child's presence is required. Adults, especially mothers, use this pattern of communication by adjusting, their linguistic and prosodic aspects of speech which construct the concept of motherese. Child-directed speech is distinctive by its slower production of utterances, and pitch contours are often pronounced more clearly and exaggerated (Brand, Baldwin & Ashburn, 2002; Bohannon & Marquis, 1977; Fernald & Mazzie, 1991; Greiser & Kuhl, 1988; Hoff-Ginsberg, 1986; Masataka, 1998; O'Neill, Bard, Linnel, & Fluck, 2005; Rowe, Pan & Coker, 2004; Sokol, Webster, Thompson & Stevens, 2005; Tamis-LeMonda & Bornstein, 1994). Several studies indicate that prosodic features of child-directed speech are far more important than its syntactic or semantic features (Greiser & Kuhl, 1988). Moreover, studies show that the exaggerated prosody of CDS increases the salience of acoustic cues to linguistic structure for the preverbal infant (Fernald & Mazzie, 1991). Additionally, the prosodic features of the maternal speech help infant to distinguish the identical syllables (Greiser & Kuhl, 1988). The evidence show, that child-directed speech is characterized by perceptual features which are more attractive to children, although it is important to investigate the contribution of motherese on language development. The study of Greiser and Kuhl (1988) provide us with three general explanations of CDS to contribution to language development.
Three major characteristics are described in a study of Greiser and Kuhl (1988) consistent of linguistic, attentional, and social/affective constructs. Linguistic explanation is characterized by expanded pitch contours which serve as indication of linguistic boundaries (Greiser & Kuhl, 1988). Moreover, by highlighting the linguistic boundaries make the language explanation more efficient (Greiser & Kuhl, 1988). In several studies of syntax growth related to maternal speech, the most frequently appearing predictor of syntax growth is the occurrence in input of expansions, reacts, and other sorts of utterances that repeat some or all of the semantic content of the prior utterance while changing the syntactic form of expression (Hoff-Ginsberg, 1986). In addition, positive effects have been found of mothers' utterances that repeat part of the child's previous utterance and of utterances in which mothers or experimenters repeat part of their own previous utterance (Hoff-Ginsberg, 1986).Naturalistic and experimental studies have also found the occurrence of yes or no questions in input to be positively associated with measure of children's syntax growth (Hoff-Ginsberg, 1986).
The attentional characteristic of CDS contributes to the level of perceived language by the infant, and the level of prominence of perceived language respectively (Greiser & Kuhl, 1988). By using high pitch contours combined with deep emotional expressions contribute to the level and prominence of perceived utterances (Greiser & Kuhl, 1988). Moreover, Sokol, et al. (2005) proposes that maternal speech patterns is more suitable for the infants immature auditory system. The study shows , that maternal pattern of speech is adjusting to infants' auditory and cognitive abilities. By adjusting to infants' auditory and cognitive abilities it is credible to draw and maintain infant's attention.
Social/affective characteristic of CDS contribute to infant's language development by regulating infant's affective state (Greiser & Kuhl, 1988). In a study of Clarck (as cited in Sokol et al., 2005) suggest that salience regulation of infant's affective state may sustain language learning at the early stages of development. The use of higher and expanded pitch contours allow mothers to assign important affective discriminative stimuli and information which will be identified by the infant as positive signals regulating the infant's affective state (Greiser & Kuhl, 1988; Sokol et al., 2005). Child-directed speech serves to adjust the affective states of the infant depending on whether the caregiver encouraging, soothing or just seeking to elicit the infant's attention (Sokol et al., 2005).
According to developmental psychologists nonlinguistic representations of the world contribute and constrain the structure of child language and the course of its development (Tamis-LeMonda & Bornstein, 1994). What is more, when interacting with infants adults alter their movements in ways that increase infant's attention to action and highlight meaningful units within the flow of motion (Brand, Baldwin & Ashburn, 2002). Mothers shape their language-related gestures to infants, using fewer gestures over all, and more often gestures to reinforce or disambiguate the verbal message, rather than to add new information (Brand et al., 2002). Gestures associated with child-directed speech called "motionese" are likely to assist infant's attention to action (Brand et al., 2002). Such reinforced attention should help infants to learn about action more readily (Brand et al., 2002). Studies show that mothers showed higher level of enthusiasm and interest in the object demonstrating to infants, which is considered reinforcing behavior for the baby (Brand et al., 2002). Additionally, increased gaze from mothers in mother's infant-directed action, help maintain infant's attention and thus can benefit in language and cognitive development (Brand et al., 2002). Overall it is important to evaluate gestures as a part child-directed speech because of their attentional and linguistic contribution to infants' development.
Child-directed speech or motherese is a universal pattern of speech with preverbal children by caregivers independent of language (Greiser & Kuhl, 1988). Some aspects of motherese as "motionese" could be found in different sign languages, whereas sign motherese shares analogous characteristics with maternal speech (Masataka, 1998). In her study Masataka (1998) found that hearing infants exposed to motherese sign language showed more interest and attraction then to adult sign language. This study support that, special properties evident in infant-directed speech may have universal attentional and affective significance (Masataka, 1998).
In addition, it is important to investigate the importance of father talk to infants and their contribution to the language development. Several studies demonstrate the difference in the ways fathers talk to their preverbal infants (Rowe et al., 2004). Fathers in Western middle-class produce more directives, more wh-questions, and more frequent requests for clarification in talk with children, thus engaging children in more complex cognitive processes (Rowe et al., 2004).Fathers tend to use directives in their indirect form which may present cognitive/linguistic challenges in interpretation (Rowe et al., 2004). By addressing the wh-questions the conversation becoming more demanding and require child to respond non-imitatively and verbally (Rowe et al., 2004). Although there are only few studies on paternal talk to the infant it is clear that CDS of father contribute to the language development by putting the child in more complex linguistic and cognitive processes.
Concluding it is important to underline aspects of motherese contributing to language development. Child-directed speech or motherese, play an important role in language development of an infant. Motherese prosodic characteristics influence directly the language development because of its slower and smooth production, higher and exaggerated pitch contours and sensitive pause distribution in utterances. Additionally, motherese influence the child affective and attentional states, which contributes indirectly to the language development. Although, there is a lot of evidence about child-directed speech positive qualities there should be more investigation about the contribution of child-directed speech to language development.
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