If you think about it, it’s pretty impressive that, given the complexity of language, infants learn to speak their first word by the time they are about a year old, and are able to talk in sentences by the age of 2. It takes us years to become fluent in a second language as adults, but infants manage to do this within just a few years. So how do they manage it?
You’ve probably noticed the strange way adults speak to babies. Kind of cooing and repetitive, this type of talking is known as infant-directed speech, or motherese. This talking actually has a purpose – it is higher in pitch than normal speech, and has more exaggerated intonation contours. It also has longer pauses between words and is made of shorter sentences. These characteristics make it easier for infants to recognise, and so helps them to learn the properties of language.
There are other characteristics of language which are thought to help babies learn words. One example of this is phonemic categories: for example ‘b’ and ‘p’ are phonemes that are very similar, but can be recognised by infants as young as 1 months old. This was shown by Eimas et al (1971) who got infants to suck on a dummy to hear sounds, and found they sucked more to the ‘new’ phoneme they hadn’t been played before.
It has been shown by Werker and Tees (1984) that young infants are able to discriminate between phonemic contrasts that older children and adults are not. This graph shows the decline in ability as they get older:
This suggests that infants become less able to discriminate between phonemic contrasts that they don’t need to know in their native language, and so helps them focus on this language.
Identifying single words in a sentence is more difficult than it would seem, as silences don’t always come between words. Infants are thought to learn word boundaries by categorical perception – the probability that one syllable will follow another. For example, Saffran et al (1996) showed that in the phrase ‘pretty baby’, there is a higher probability that ‘ty’ will follow ‘pret’ than ‘ba’ would follow ‘ty’. They suggested that babies use this method to work out the gaps between words.
Not surprisingly, infants learn words faster if they are exposed to more language. Hart and Risley (1995) found that in the USA, a family’s social economic status affects the amount of language they are exposed to: high SES families = 487 utterances per hour, while for low SES families, it is 178 utterances per hour. This shows the importance of environment in language learning.
Hope you found this post interesting, check back soon for more 🙂