Factors Contributing to Variations in Rate of Language Acquistion (page 2)
Since the critical period for language development occurs within the first thirty-six months of a child’s life, significant language delay may indicate specific medical or cognitive problems. Beyond medical problems, there are several factors that could modify the rate of normal language production. We review these factors in the following discussion.
Are there differences in the rate and ways that boys and girls develop language fluency and proficiency? This question reflects another facet of the ongoing nature versus nurture debate. Observational research consistently reveals that a majority of girls talk earlier and talk more than the majority of boys. It is also true that the majority of late talkers are young boys (Healy, 1997; Kalb & Namuth, 1997). However, it is difficult to determine whether differences in the rate of language acquisition are biological or if biological differences are exaggerated by social influences. There is evidence for both views. For example, neurobiological research offers graphic images that illustrate how men’s and women’s brains process language somewhat differently (Corballis, 1991; Moir & Jessel, 1991). Though this research appears to support nature as the dominant factor in language differences, it is also important to consider how powerful a role nurture plays. Experimental research consistently documents differential treatment of infants based on gender. In other words, men and women tend to cuddle, coo at, and engage in lengthy face-to-face conversations with baby girls. Yet with baby boys, adults are likely to exhibit “jiggling and bouncing” behaviors but are not as likely to engage in sustained face-to-face verbal interactions. Perhaps girls talk earlier and talk more because they receive more language stimulation (Huttenlocher, 1991).
Numerous studies have long documented the differences in the rate of language acquisition and the level of language proficiency between low and middle socioeconomic families (Hart & Risley, 1995; Morisset, 1995; Walker, Greenwood, Hart, & Carta, 1994). These studies found that children, especially males, from low-income homes were usually somewhat slower to use expressive language than children from middle-income homes. These findings likely reflect social-class differences both in language use in general and in parent–child interaction patterns. For example, Betty Hart and Todd Risley (1995) estimate that by age four, children from professional families have had a cumulative total of 50 million words addressed to them, whereas children from welfare families have been exposed to only 13 million words. The children from professional families have had more than three times the linguistic input than welfare families’ children; this gives them a tremendous advantage in language acquisition.
Results of long-term observations of middle-income and lower-income families concluded that all mothers spent a great deal of time nurturing their infants (e.g., touching, hugging, kissing, and holding), but that there were differences in the way mothers verbally interacted with their children. Middle-income mothers spent a great deal more time initiating verbal interactions and usually responded to and praised their infants’ vocal efforts. Middle-income mothers were also more likely to imitate their infants’ vocalizations. These verbal interactions stimulate neural-synapse networks that foster expressive and receptive language. It is still unclear why lower-income mothers do not engage their children in verbal interactions at the same level as middle-income mothers. The authors of these studies speculate that this may be a reflection of social-class differences in language use in general.
The rate of language acquisition may be somewhat different for children of different cultures. Since spoken language is a reflection of the culture from which it emerges, it is necessary to consider the needs verbal language serves in the culture. Communication may be accomplished in other meaningful nonverbal ways (González, Oviedo, & O’Brien de Ramirez, 2001; Bhavnagri & Gonzalez-Mena, 1997).
Likewise, some cultures do not view babies’ vocal attempts as meaningful communication. Shirley Brice Heath (1983) describes a community in which infants’ early vocalizations are virtually ignored and adults do not generally address much of their talk directly to infants. Many cultures emphasize receptive language, and children listen as adults speak.
Beyond gender, socioeconomic, and culture differences, other reasons that children’s language may be delayed include temporary medical problems and congenital complications. Estimates of hearing impairments vary considerably, with one widely accepted figure of 5 percent representing the portion of young children with hearing levels outside the normal range. Detection and diagnosis of hearing impairment have become very sophisticated. It is possible to detect hearing loss and evaluate its severity in a newborn child.
Congenital Language Disorders
For most children, learning to communicate is a natural, predictable developmental progression. Unfortunately, some children have congenital language disorders that impair their ability to learn language or use it effectively. The origin of these disorders may be physical or neurological. Examples of physical problems include malformation of the structures in the inner ear or a poorly formed palate. Neurological problems could include dysfunction in the brain’s ability to perceive or interpret the sounds of language.
Though the symptoms of various language disorders may appear similar, effective treatment may differ significantly, depending on the cause of the problem. For example, articulation problems caused by a physical malformation of the palate might require reconstructive surgery, while articulation problems caused by hearing impairment might require a combination of auditory amplification and speech therapy. Two of the most common symptoms of congenital language disorders are disfluency and pronunciation.
Children with fluency disorders have difficulty speaking rapidly and continuously. They may speak at an abnormal rate—too fast or too slow; in either case, their speech is often incomprehensible and unclearly articulated. The rhythm of their speech may also be severely affected. Stuttering is the most common form of this disorder. Many children may have temporary fluency disruptions or stuttering problems as they are learning to express themselves in sentences. Children who are making a transition to a second language may also experience brief stuttering episodes. It is important for parents or teachers to be patient and supportive, as it may take time to distinguish normal developmental or temporary lapses in fluency from a true pathology. Stuttering may have multiple origins and may vary from child to child. Regardless of cause, recently developed treatment protocols have been effective in helping stutterers. (Dodd & Bradford, 2000).
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