A biological perspective of language

Language in adults with Down syndrome

“…Second, once they have started developing, linguistically exceptional intellectually impaired subjects proceed relatively quickly in their grammatical development (over a 4 or 5 year-period as it would seem) but, and this is the crucial point, within childhood. All in all, the above data are fairly compatible with the hypothesis of the existence of a critical period for computational language development in intellectually impaired as well as in non-intellectually impaired children, as suggested by Lenneberg (1967). As is known, this hypothesis has found a convincing empirical basis in the work of Curtiss and associates with Genie, a modern-day "wild child" kept away from social contact for most of the 13 years of her life (Curtiss, 1977), and in the repeated demonstration (e.g., Mayberry, Fisher, andHatfield, 1983, Ploog, 1984;Newport, 1984Newport, , 1990Newport, , 1992) that "late" learners of the American Sign Language (ASL, the esoteric sign system used by deaf people in the United States of America) -i.e., deaf individuals first exposed to ASL after age 12 -never learn to sign and never develop grammatical knowledge in ASL as native ASL signers or subjects first exposed to ASL in their earlier years, even after 30 years of practice.…”

“…Basically the same conclusion can be reached regarding a possible language evolution from late childhood (say 12-14 years) and adolescence in Down syndrome (and other intellectually impaired) individuals, using the series of comparative data available (Bleile and Schwartz, 1984;Bray and Woolnough, 1988;Comblain, 1994;Dodd, 1976;Fowler, 1988;Fowler, Gelman, and Gleitman, 1994;Lenneberg, 1967;Rondal, 1978;Rondal et al, 1981;Rosenberg and Abbeduto, 1993;Ryan, 1975;Smith and Stoel-Gammon, 1983;Stoel-Gammon, 1980;Van Borsel, 1988).…”

The Effect of Age on the Ultimate Attainment of English Lexis and Morphosyntax

“…Their age of onset of learning (6 years) indicates that they were in the midway through their CP when they could have still maintained their brain plasticity (Penfield and Roberts, 1959) and lateralization is slowly taking shape in their brains (Lenneberg, 1967). However, by Krashen and Pinker's calculations these learners are right on the top of the hill of their CP where lateralization is totally complete (Bialystok, Hakuta and Wiley, 2003).…”

“…In 1959, two Canadian brain surgeons, Penfield and Roberts, claimed to have found evidence suggesting that before the age 9, children are able to relearn language when injury or disease damages speech area in their brains, however, this capacity declines abruptly soon afterward. A decade later, Lenneberg (1967) as investigating cases of aphasic patients and feral children, discovered that early in life the human brain is characterized by a rapid growth of nerve connection that is coupled with an equivalent development of language capacity. According to Lenneberg (1967), children maintain this capacity up until the onset of their puberty, around the age of 12, but beyond this period, this capacity wanes and learning a language, then, requires some 'laboured' efforts.…”

Development of the Lurian Approach: A Cultural Neurolinguistic Perspective

“…The problem of age differences in language learning has been discussed extensively among experts in language learning ever since the Hypothesis of the Critical Period was suggested. The hypothesis claims that humans are capable of proficient language learning (both mother tongue and second language) only before the early teens, and that afterward the brain mechanisms are "frozen," with proficiency never reaching a level of perfection (in particular, ridding oneself of a foreign accent was considered impossible) (Lenneberg, 1967). A variety of explanations were suggested for the apparent decline in the abilities of new language learning in adults: physical such a loss of "plasticity" and established "lateralisation" of the brain; social factors such as different relationships; life situations and such cognitive explanations as different degrees of interference with natural language learning; and the adult's abstract mode of thinking (Cook, 1991).…”