Cases of exceptional language in mental retardation and Down syndrome: explanatory perspectives.
(9/705)
Recent studies of exceptional language development and functioning in mentally retarded people raise questions regarding basic issues in language disorders. These studies are summarised and their implications discussed. Possible reasons for the existence of such cases are examined including language training, general cognitive functioning, working memory, cerebral dominance, and deep-seated variation at brain level. (+info)
Using augmentative communication with infants and young children with Down syndrome.
(10/705)
This paper reports the use of two forms of augmentative and alternative communication (AAC) with young children with Down syndrome: a program using signing (Makaton), and the COMPIC system of computerised pictographs. Children with Down syndrome are frequently reported to have difficulties in the area of language and communication, with relative strengths in visual and perceptual areas. This suggests possible benefits from the use of AAC systems to enhance language development. The paper discusses the use of AAC systems to assist young children with Down syndrome, and reports an experimental study of the use of such systems with an object naming task. (+info)
A new view of language acquisition.
(11/705)
At the forefront of debates on language are new data demonstrating infants' early acquisition of information about their native language. The data show that infants perceptually "map" critical aspects of ambient language in the first year of life before they can speak. Statistical properties of speech are picked up through exposure to ambient language. Moreover, linguistic experience alters infants' perception of speech, warping perception in the service of language. Infants' strategies are unexpected and unpredicted by historical views. A new theoretical position has emerged, and six postulates of this position are described. (+info)
Growth, development, and behavior in early childhood following prenatal cocaine exposure: a systematic review.
(12/705)
CONTEXT: Despite recent studies that failed to show catastrophic effects of prenatal cocaine exposure, popular attitudes and public policies still reflect the belief that cocaine is a uniquely dangerous teratogen. OBJECTIVE: To critically review outcomes in early childhood after prenatal cocaine exposure in 5 domains: physical growth; cognition; language skills; motor skills; and behavior, attention, affect, and neurophysiology. DATA SOURCES: Search of MEDLINE and Psychological Abstracts from 1984 to October 2000. STUDY SELECTION: Studies selected for detailed review (1) were published in a peer-reviewed English-language journal; (2) included a comparison group; (3) recruited samples prospectively in the perinatal period; (4) used masked assessment; and (5) did not include a substantial proportion of subjects exposed in utero to opiates, amphetamines, phencyclidine, or maternal human immunodeficiency virus infection. DATA EXTRACTION: Thirty-six of 74 articles met criteria and were reviewed by 3 authors. Disagreements were resolved by consensus. DATA SYNTHESIS: After controlling for confounders, there was no consistent negative association between prenatal cocaine exposure and physical growth, developmental test scores, or receptive or expressive language. Less optimal motor scores have been found up to age 7 months but not thereafter, and may reflect heavy tobacco exposure. No independent cocaine effects have been shown on standardized parent and teacher reports of child behavior scored by accepted criteria. Experimental paradigms and novel statistical manipulations of standard instruments suggest an association between prenatal cocaine exposure and decreased attentiveness and emotional expressivity, as well as differences on neurophysiologic and attentional/affective findings. CONCLUSIONS: Among children aged 6 years or younger, there is no convincing evidence that prenatal cocaine exposure is associated with developmental toxic effects that are different in severity, scope, or kind from the sequelae of multiple other risk factors. Many findings once thought to be specific effects of in utero cocaine exposure are correlated with other factors, including prenatal exposure to tobacco, marijuana, or alcohol, and the quality of the child's environment. Further replication is required of preliminary neurologic findings. (+info)
Natural selection of the critical period for language acquisition.
(13/705)
The language acquisition period in humans lasts about 13 years. After puberty it becomes increasingly difficult to learn a language. We explain this phenomenon by using an evolutionary framework. We present a dynamical system describing competition between language acquisition devices, which differ in the length of the learning period. There are two selective forces that play a role in determining the critical learning period: (i) having a longer learning period increases the accuracy of language acquisition; (ii) learning is associated with certain costs that affect fitness. As a result, there exists a limited learning period which is evolutionarily stable. This result is obtained analytically by means of a Nash equilibrium analysis of language acquisition devices. Interestingly, the evolutionarily stable learning period does not maximize the average fitness of the population. (+info)
Effect of maternal education and ethnic background on infant development.
(14/705)
We examined the influence of maternal education and ethnic background on the four main areas of development (as measured by the Brunet-Lezine adaptation of Gesell's developmental schedule) of their infants. 173 babies were examined at the ages 0f 3, 6, 9, and 12 months in the Kiryat Yovel area of Jerusalem, an area where Jew from North Africa, Asia, Europe, and Israel are represented at different educational levels but all share the saem maternal and child care services. The mean development quotients (dqs) of the infants of highly educated mothers were higher in all four areas of development that those of infants whose motherw were of low education. Further, North African infants of middle educated mothers had higher DQs than those of middle education European mothers, especially in motor and adaptive areas. It was concluded from this study that higher education of mothers will be expressed in higher DQs of their babies. This was true in all ethnic groups. However, where educational groups were comparable, North African babies have shown better development than all other groups, while European babies were the least developed. (+info)
Developmental milestones of vertically HIV infected and seroreverters children: follow up of 83 children.
(15/705)
The aim of the study was to detect neurological abnormalities in human immunodeficiency virus (HIV) infected children. This was achieved by a prospective evaluation, from November/1995 to April/2000, of 43 HIV infected children (group I) and 40 HIV seroreverters children (group II) through neurological exam and neurodevelopmental tests: Denver Developmental Screening Test (DDST) and Clinical Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS). A control group (III), of 67 children, were evaluated by CAT/CLAMS. Hyperactivity, irritability and hypotonia were the findings on neurological examination, without statistical differences between group I and II. On CAT/CLAMS, the group I developmental quotient (DQ) was significantly lower than the other groups. The same occurred in DDST, with group I presenting significantly more failures than group II. Nineteen HIV children of group I had brain computed tomographic scan, with abnormalities in three of them (basal ganglia calcification, white matter hypodensity and asymmetry of lateral ventricles). We conclude that in HIV infected children a neurodevelopment delay occur early in the disease, and it can be detected by screening tests. (+info)
Cost and conflict in animal signals and human language.
(16/705)
The "costly signaling" hypothesis proposes that animal signals are kept honest by appropriate signal costs. We show that to the contrary, signal cost is unnecessary for honest signaling even when interests conflict. We illustrate this principle by constructing examples of cost-free signaling equilibria for the two paradigmatic signaling games of Grafen (1990) and Godfray (1991). Our findings may explain why some animal signals use cost to ensure honesty whereas others do not and suggest that empirical tests of the signaling hypothesis should focus not on equilibrium cost but, rather, on the cost of deviation from equilibrium. We use these results to apply costly signaling theory to the low-cost signals that make up human language. Recent game theoretic models have shown that several key features of language could plausibly arise and be maintained by natural selection when individuals have coincident interests. In real societies, however, individuals do not have fully coincident interests. We show that coincident interests are not a prerequisite for linguistic communication, and find that many of the results derived previously can be expected also under more realistic models of society. (+info)