Psychology - Language Development

In this video, we're learning about language development. So we'll cover the stages of language development, theoretical explanations for language development from Skinner and Chomsky, and finally, the critical period hypothesis. Let's start by looking at the stages of language development. Interestingly, the stages seem to follow the same sequence for children all around the world, regardless of which language they're learning or what culture they're growing up in. This universal pattern suggests that language development follows a predictable path, and researchers have broken that path down into four key stages. The first stage is cooing and babbling, which begins in infancy. Cooing involves making soft vowel sounds like u and a, and this typically starts around two months of age. Babbling is when infants start combining consonants and vowels to produce sounds like baba or dada. It comes a bit later, typically starting around six months. And at this point, these sounds don't have any meaning attached to them, but they're important practice for the vocal muscles and sounds needed for later speech. The next stage is the one-word stage, which is also called the holophrastic stage. This typically begins around 12 months of age, and it's when children start using single words to communicate whole ideas. For instance, a child might say milk to mean, I want milk, or more to mean, give me more food. The term holophrastic just means that a single word, or holophrase, is being used to express a complete thought. Following this is the two-word stage, which usually begins around 18 to 24 months. During this stage, children start to combine two words together to form simple phrases, like mummy go or more juice. These combinations show that children are beginning to understand basic grammatical relationships, even though their sentences are still very short. The final stage we need to understand is telegraphic speech, which typically appears at around two to three years of age. We use the term telegraphic to describe sentences that are grammatically structured but simplified, much like in old telegrams where people paid by the word. So a child might say daddy go work, instead of daddy is going to work. The key grammatical elements are there, but the smaller words like is and to are left out. Next, let's explore some key theoretical explanations for language development, focusing on two quite different perspectives from Skinner and Chomsky. First, Skinner proposed that language is learned through operant conditioning, which is learning through reinforcement and consequences. According to Skinner's behaviorist view, children learn language because their attempts at speech are reinforced by their caregivers. So when a baby babbles something that sounds like mama, the mother responds with excitement and attention, which reinforces the behavior and makes the child more likely to repeat it. Over time, through this process of reinforcement, these vocalizations are gradually shaped into proper words and sentences. On the other hand, Chomsky took a very different view, arguing that language is far too complex to learn purely through reinforcement. His perspective is called the nativist view, and it proposes that humans are born with an innate natural ability to learn language. He suggested that we have what he called a language acquisition device, which is essentially an inborn mental structure that allows children to acquire language even without reinforcement. This language acquisition device is thought to contain knowledge of a universal grammar, which refers to the basic underlying principles that all human languages share at a deep level, even though they look quite different on the surface. For instance, all languages seem to have ways of distinguishing between things, like nouns, and actions, like verbs. This disagreement between Skinner and Chomsky reflects the broader nurture versus nature debate in psychology. While Skinner's view emphasizes nurture, suggesting that environmental factors like reinforcement shape language development, Chomsky's view emphasizes nature, arguing that our biology provides us with a fundamental capacity for language. Most psychologists today accept that both nature and nurture play important roles, but Chomsky's critique highlighted that reinforcement alone struggles to explain how children learn language so quickly and can produce sentences that they've never heard before. Finally, let's look at the critical period hypothesis, which was proposed by Lenneberg in 1967. He suggested there's an optimal window for language acquisition, which he called the critical period. According to his hypothesis, children need to be exposed to language during this specific period of biological development, which is typically before puberty, in order to acquire language fully and naturally. And after this window closes, language acquisition becomes much more difficult. Evidence for this hypothesis came from the case of a girl called Jeannie, who was discovered in 1970 after she experienced severe isolation and neglect throughout her childhood. She had been kept locked away and deprived of normal human interaction until she was 13 years old. Despite intensive language training after her discovery, Jeannie never fully developed normal language abilities, particularly in terms of her grammar and syntax, which just refers to how words are arranged to form sentences. These findings from Jeannie's case provide support for the critical period hypothesis, because her inability to fully acquire language suggests the critical window had already closed by the time she was 13. This is also seen as supporting the broader nativist view, because it suggests there's a biological timetable for language acquisition, rather than it being purely down to exposure and reinforcement. A key limitation of using Jeannie's case as evidence, though, is that it involved severe trauma and deprivation beyond just language isolation, so we need to take these findings with a pinch of salt. We can't be certain whether her difficulties were due to missing the critical period for full language acquisition, or whether other trauma may have caused language difficulties. If you haven't heard yet, you can find all of our videos on our website. You'll also find questions, flashcards, exam-style questions, and past papers. 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