The Articulate Mammal (18 page)

A similar consistency of order is found in the acquisition of more complicated constructions, such as
questions
and
negatives
. For example, in the acquisition of WH- questions (questions beginning with WHAT, WHY, WHERE, WHO, etc.), we can safely assume that Barbara, like Adam, Eve and Sarah, went through three intermediate stages before she acquired them perfectly (Klima and Bellugi 1966). First of all, soon after her second birthday, she placed the WH-word in front of the rest of the sentence:

A second stage occurred three or four months later when she added an auxiliary verb such as CAN or WILL to the main verb:

Finally, before she was 3, she realized that the subject noun must change places with the auxiliary and produced correct sentences such as:

Once again, the rather surprising finding that all English children tend to follow a similar pattern will be discussed later. As already noted, the actual
age
at which each stage is reached is irrelevant. It is the order which matters.

By the age of 3½, Barbara, like most children, was able to form most grammatical constructions – and her speech was reasonably intelligible to strangers. Her constructions were, however, less varied than those of an adult. For example, she tended not to use the ‘full’ passive such as THE MAN WAS HIT BY A BUS. But she was able to converse quite adequately on most topics.

By 5, she gave the superficial impression of having acquired language more or less perfectly. But this was an illusion. Language acquisition was still continuing, though more slowly. The grammar of a child of 5 differs to a perhaps surprising degree from adult grammar. But the 5-year-old is not usually aware of his shortcomings. In comprehension tests, children readily assign interpretations to the structures presented to them – but they are often the wrong ones. ‘They do not, as they see it, fail to understand our sentences. They understand them, but they understand them wrongly’ (Carol Chomsky 1969: 2). To demonstrate this point, the researcher showed a group of 5- to 8-year-olds a blindfolded doll and said: ‘Is this doll hard to see or easy to see?’ All the 5- and 6-year-olds said HARD TO SEE, and so did some of the 7- and 8-year-olds. The response of 6-year-old Lisa was typical:

Some psychologists have criticized this particular test. A child sometimes believes, ostrich-fashion, that if his own eyes are covered, others will not be able to see him. And he may be partly switching to the doll’s viewpoint when he says a blindfolded doll is hard to see. But a re-run of this experiment using wolf and duck puppets, and sentences such as:

THE WOLF IS HARD TO BITE .

THE DUCK IS ANXIOUS TO BITE.

confirmed the original results (Cromer 1970). Children of 5 and 6 just do not realize that pairs of sentences such as THE RABBIT IS NICE TO EAT and THE RABBIT IS EAGER TO EAT have completely different underlying meanings.

In fact, the gap between child and adult speech lasts longer than was once realized. Detailed experiments on French children’s understanding and use of the articles LE/LA ‘the’ and UN/UNE ‘a’ have shown quite surprising differences between child and adult usage, which remained in some cases up till the age of 12 (Karmiloff-Smith 1979).

But the discrepancies between Barbara’s speech and that of the adults around her gradually disappeared over the next few years. By the age of about 11, Barbara exhibited a command of the structure of her language comparable to that of an adult. At the age of puberty, her language development was essentially complete, apart from vocabulary. She would continue to accumulate lexical items throughout her life.

The language milestones we have outlined tend to run parallel with physical development. Clearly, there is no essential correlation between language and motor development, since there are numerous examples of children who learn to talk, but never walk, and vice versa. However, researchers are agreed that in normal children the two often go together. Language stages are often loosely linked to physical milestones. The gradual change of cooing to babbling occurs around the time an infant begins to sit up. Children utter single words just before they start to walk. Grammar becomes complex as hand and finger co-ordination develops.

We now need to discuss one final point. Is it crucial for children to develop language at the age they normally do? According to the sixth and final characteristic of maturationally controlled behaviour, there may be a ‘critical period’ for its acquisition, though this is not essential. Is this true of language? Let us consider this matter.

IS THERE A ‘CRITICAL PERIOD’?

Are humans like chaffinches? Or like canaries? Both these birds have to partially learn their songs. But a chaffinch’s song becomes fixed and unalterable when it is around 15-months old. If the young bird has not heard any chaffinch song before that time, it never learns to sing normally (Thorpe 1972). But canaries can continue to alter their song for years (Nottebohm 1984; Marler 1988). Lenneberg argued that humans, like chaffinches, have a narrow ‘critical period’ set aside by nature for the acquisition of language. In his view, it lasts from toddler time to adolescence:

Between the ages of two and three years language emerges by an interaction of maturation and self-programmed learning. Between the ages of three and the early teens the possibility for primary language acquisition continues to be good … After puberty, the ability for self-organization and adjustment to the physiological demands of verbal behaviour quickly declines. The brain behaves as if it had become set in its ways and primary, basic skills not acquired by that time usually remain deficient for life.

(Lenneberg 1967: 158)

At one time, Lenneberg’s views were widely accepted. Children clearly start talking at about the age of 2. And it seemed plausible that language ability ceased at around 13. Almost everybody can remember how difficult it was to learn French at school. Even the best pupils had a slightly odd accent, and made numerous grammatical mistakes. It was comforting to believe that there was a biological explanation for this. On closer inspection, however, the matter is not so clear cut.

Lenneberg appears to be right in outline, but wrong in some details. The early part of life is indeed important for language, though it all starts earlier than he assumed. Lenneberg argued for a link between a critical period and lateralization, the specialization of language to one side of the brain (
Chapter 3
). This process, in his view, happened slowly, between the ages of 2 and 14. He was probably wrong about this. Lateralization is established much earlier than he suggests. Even babies under a year old show some evidence of it. In one experiment, 5- and 6-month-old infants were presented with sounds and lip movements which were sometimes synchronized, sometimes not. They seemed to notice the synchrony only when the direction of their gaze showed that they were using their left hemisphere (MacKain
et al.
1983). So lateralization is evident in the first few months of life. And as soon as young children can be tested with dichotic listening (
Chapter 3
), around age 2½ or 3, they seem to be using their left hemisphere for language (Kinsbourne and Hiscock 1987).

Lenneberg also claimed that if a child under the age of 2 sustained severe damage to the left (language) hemisphere of the brain, speech would develop normally, though it would be controlled by the right hemisphere. The ‘critical period’ had in his view not yet begun. But he was wrong to assume that children under 2 would not be affected by left hemisphere damage. On the contrary, babies who have had this half of their brain removed in the first year of life have considerable language problems (Dennis 1983; Vargha-Khadem and Polkey 1992). Severe left hemisphere injury usually results in permanent linguistic impairment, whatever the age of the patient.

But Lenneberg is right that a huge language surge occurs at around the age of 2. And his claim that the language of younger children is less severely impaired by brain damage than the speech of older ones appears to be true (Vargha-Khadem
et al.
1985). This is not surprising. Young brains have greater powers of recovery. Infant monkeys with brain damage recover faster than older ones (Goldman-Rakic 1982).

But does language come to a shuddering halt around adolescence, as Lenneberg believed? The cases of three socially isolated children, Isabelle,
Genie and Chelsea, provide superficial support for this view. All three were cut off from language until long after the time they would have acquired it, had they been brought up in normal circumstances.

Isabelle was the illegitimate child of a deaf mute. She had no speech, and made only a croaking sound when she was found in Ohio in the 1930s at the age of 6½. Mother and child had spent most of the time alone in a darkened room. But once found, Isabelle’s progress was remarkable:

Isabelle passed through the usual stages of linguistic development at a greatly accelerated rate. She covered in two years the learning that ordinarily occupies six years. By the age of eight and a half, Isabelle was not easily distinguishable from ordinary children of her age

(Brown 1958: 192)

Genie, however, was not so lucky. She was not found until she was nearly 14. Born in April 1957, she had lived most of her life in bizarre and inhuman conditions:

From the age of twenty months, Genie had been confined to a small room … She was physically punished by her father if she made any sounds. Most of the time she was kept harnessed into an infant’s potty chair; otherwise she was confined in a homemade sleeping bag in an infant’s crib covered with wire mesh.

(Curtiss
et al.
1974: 529)

When found, she was totally without language. She began acquiring speech well after the onset of adolescence – after the proposed ‘critical period’.

Although she learnt to speak in a rudimentary fashion, she progressed more slowly than normal children (Curtiss 1977). For example, ordinary children go through a stage in which they utter two words at a time (WANT MILK, MUMMY PLAY), which normally lasts a matter of weeks.

Genie’s two-word stage lasted for more than five months. Again, ordinary children briefly pass through a phase in which they form negative sentences by putting the word NO in front of the rest of the utterance, as in NO MUMMY GO, NO WANT APPLE. Genie used this primitive form of negation for over two years. Normal children start asking questions beginning with words such as WHERE, WHAT, at the two-word stage (WHERE TEDDY?). Genie found this kind of question impossible to grasp, occasionally making inappropriate attempts such as WHERE IS STOP SPITTING? The only aspect of speech in which Genie outstripped normal children was her ability to learn vocabulary. She knew many more words than ordinary children at a comparable stage of grammatical development. However, the ability to memorize
lists of items is not evidence of full language capacity, even the chimps Washoe and Sarah found this relatively easy. The rules of grammar are crucially important, and this is what Genie found difficult. Her slow progress compared with that of Isabelle seemed to provide evidence in favour of a ‘cut-off’ point for language acquisition. We must be cautious, however. Two individual cases cannot provide firm proof, especially as each is problematical. Isabelle was not studied by linguists, so her speech may have been more deficient than was reported. Genie, on the other hand, showed some evidence of brain damage. Tests suggested that her left hemisphere was atrophied, which meant that she was functioning with only one half of her brain, the half not usually associated with language. The final chapter of Genie’s story is depressing. Her mother removed her from the care of those who conversed with her. Left hospitalized and alone, she stopped talking. ‘It’s a fated case’, commented one of her psychiatrists. ‘You have a second chance in a situation like that – a chance to rescue the child. But you don’t get a third chance, and that’s the situation now’ (Rymer 1993: 223).