Psychology 101: Intro to Psychology

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Have you ever wondered how humans are able to learn, process, comprehend and speak a language? In this lesson on language acquisition, we'll take a look at some distinctions between languages and learn how babies come to understand and speak a language.

Once we fully understand language's complexity, it seems truly amazing that babies can learn to speak and understand without direct instruction. Studies of language acquisition are an important part of infant psychology that shed light on how our minds process language even as adults. We'll go over some debates in the field of language acquisition, take a look at an experiment used to study infants' abilities to understand speech and finally go over some of the main stages of language acquisition.

One of the big questions for psychologists who study language acquisition is whether we have innate language centers in our brains, or whether language is completely dependent on learning. This echoes the larger nature vs. nurture debate that underlies questions in many areas of psychology. The world famous linguist Noam Chomsky believes that everyone has a universal grammar hard-wired into their brains. He's come to this conclusion by looking at grammatical features shared among diverse languages. Scientists who have looked for the brain's language center have found some regions that impede language production and understanding when they're damaged. Broca's area seems to be involved in production, and Wernicke's area with understanding. But neither have been shown to house Chomsky's universal grammar. Chomsky's critics have also argued that there are obscure languages, like Pirahã, spoken by people in the Amazon region, that don't follow his 'universal' rules.

While some psychologists choose to tackle big questions, others prefer to study the specifics of how language is learned. As an example, have you ever wondered why people who learn a second language usually speak it with an accent?

Each language has its own distinct set of phonemes, or vowels and consonant sounds, not all of which exist in English. Adults raised in one language are often unable to hear and reproduce the subtle differences between a phoneme in their native tongue and a similar phoneme in another language. As an example, Japanese speakers learning English have difficulty distinguishing between 'l' and 'r' because they have a single phoneme that is pronounced as something in between an 'l' and an 'r.'

But regardless of where they're born or what language their parents speak, infants are able to distinguish between all possible phonemes. Researchers studied this by designing a clever experiment to tell if babies could tell when a voice speaking a Hindi consonant that sounds like 't' changed to speaking another Hindi consonant that is slightly different, but also sounds like 't' to English speakers. First, the researchers conditioned the infants to turn their heads to the side when they heard a change in sound. They would pair the sound changes with an exciting animated display that played next to the baby; this encouraged the baby to turn his head toward the display when he heard a sound change. Once this behavior was conditioned, researchers started playing the first Hindi consonant. When they switched to the second Hindi consonant the babies turned their heads toward the display. The researchers found that babies were able to distinguish sounds like this until they were about 12 months old. Since 12 months is also the time at which infants start attempting to imitate words in their language, it seems that a key part of speaking and understanding language is recognizing which phonemes are 'allowed' and which are not. If you try to speak another language, you lack this sense and speak with an accent.

Experiments like this one with Hindi consonants give psychologists a better sense of what's going on in the brain as children learn language. Psychologists have observed that infants and children typically go through five distinct stages in their ability to produce and understand speech.

Stage 1: By the time they're about two months old, babies start uttering speechlike sounds: 'goos' and 'gaaahs,' 'cooos,' 'oooohhs' and 'aahhs.' Even though it sounds like nonsense, it's far from useless, because it helps babies to practice and get ready for producing speech.

Stage 2: Between six and seven months old, babies start babbling repetitive syllables, such as 'bababa.' These syllables include phonemes from the baby's native language, but they don't yet involve actual words. Psychologists believe that babbling helps babies prepare physically for speech, but also to come to an understanding about what speech is for: communicating. Babies who learn sign language even babble with their hands!

Stage 3: Next, when a baby is about 12 months old, they begin to speak words. Even though at first they can only speak a few words, they understand many more! Usually each utterance is just one word. This is called the holophrastic stage. At 12 months, most kids can produce three or four words and understand 30-40. At this point, they tend to overextend the meanings of words, such as by using the word 'dada' for all men, not just their own father. Certain words tend to be learned earliest, including 'mama' and 'daddy,' and also 'no' and 'up.'

Stage 4: At around 18 months, babies are able to recognize and point to objects when they are named. They can also follow simple directions and their vocabulary continues to grow. They begin speaking in simple, 2-word sentences, such as 'baby hungry' or 'dog brown.'

Stage 5: When they're 25 months and older, toddlers begin to use more complex sentences, consisting of three or more words. Their vocabulary grows, so that by the age of five they know more than 10,000 words.

So, we've covered language acquisition from a lot of angles. First, we looked at the debate over Noam Chomsky's idea of universal grammar. Then, we went over an experiment designed to test how and when infants come to learn which phonemes are valid for the language they're learning. Finally, we went over the five key stages of language development in children.