Developmental outcomes have been noted influencing a number of early experiences, for example, new-borns who experience pain are found to reach optimal developmental outcomes slower (Valeri, Holsti & Linhares, 2015), a negative caregiving experience can negatively impact our development (Fraley, Roisman & Haltigan, 2013) and also children who are institutionalised from a young age will show poor developmental outcomes later on in life (Rakhlin et al., 2017). Language affecting developmental outcomes is also a well-studied area (Harris, 2014) which is found to be of key importance especially regarding language, emotional, social and cognitive development (Snow & Van Hemel, 2008). This will be discussed in depth alongside theories of language acquisition to help explain why language experiences are so important. Finally, other factors which may be more important at impacting developmental outcomes will be considered.
A prime example of how early language experience can affect developmental outcomes is the case of Genie Wiley. She was locked away in social isolation for around 13 years due to strict orders from her father that her mother and brother should not communicate with her (Rymer, 1993). When she was found she could only make ‘infantile’ noises but through the help of a team of scientists, she was able to form a substantial vocabulary early on after her discovery. However, this progress started to level off and she was not able to use this vocabulary to form sentences or grammatically correct phrases Rymer (1993). Thus, her language and communication skills were affected massively.
Due to the inability to recreate her lack of language experience in a laboratory setting, Genie’s case was hugely influential and it did enable a leap in language research, however, some question whether we can really apply such a unique case to the general population. She suffered from severe physical abuse and was in social isolation for 13 years. Thus, some may suggest the findings are not applicable to ‘normal’ humans as her experience was too unique and her experience may have changed how language was learned in a way which wouldn’t occur within an average upbringing. Nevertheless, we can relate Genie’s case to a few language acquisition theories to help us understand how language is acquired and therefore why it is important for developmental outcomes.
Skinner’s learning theory (Skinner, 1957) proposed children learn language through reinforcement, for example, when a child says a word correct if an adult smiles or praises them this will act as positive reinforcement and thus encourage the acquisition of language. Consequently, if a child is deprived of interactions and rarely hears spoken language or feedback from caregivers, then it would have huge implications on their developmental outcomes due to being unable to develop language.
Genie was able to learn a vast vocabulary but wasn’t able to form sentences or use grammar correctly, suggesting learning on its own cannot lead to language acquisition otherwise her language abilities would have developed fully with the help of her team teaching her. Some may suggest this was due to Genie missing her ‘critical period of language acquisition’ which is believed to be in the first year of life, and individuals which miss this can expect severe syntax issues as they grow older (Friedmann & Rusou, 2015). This could explain why if an individuals language experience is poor in the first year of life, this may lead to poor consequences for their developmental outcomes. However, some suggest this may only be true for first language learning as there doesn’t seem to be an effect with second language learning (Snow & Hoefnagel-Hohle, 1978).
Chomsky’s also criticised the learning theory saying the infinite number of sentences learned by an individual cannot possibly be acquired solely by learning through reinforcement as Skinner suggests (Chomsky, 1965), also demonstrating why Genie may have been unable to fully grasp language and grammatical rules. Instead, Chomsky put forward his universal grammar theory of language acquisition (Chomsky, 1965) which proposes we have a biological language acquisition device (LAD) which drives us to develop language. He believes this has parameter settings which means it is flexible enough to adapt to the features of whichever language we may be exposed to as infants, hence the name, universal grammar.
Support for this innate drive to acquire language can be seen in pidgins which develop as a result of a collation of individuals with unique languages combining features to create a distinctive and shared but simple language. An example of this is the Nicaraguan sign language. Before the 1970s in Nicaragua, deaf people were isolated, due to there being no deaf community, and had to use home sign systems to communicate. In 1977 a programme was made for deaf children which led to the birth of a pidgin-like language developed through the children combining elements of their own home-sign systems (Senghas & Coppola, 2001). This demonstrates how maybe early language experience isn’t as important to the development of language later on in life as initially suggested due to what appears to be an inherent drive for language acquisition.
Nevertheless, the importance of the environment in language acquisition and later language development may be in-between what is proposed by the nativist universal grammar theory and behaviourist learning theory. Research looking at the use of simple, more manageable and recognizable chunks of speech being used when speaking to infants, known as child directed speech (CDS) (Dockrell & Messer, 1999) has evidenced how the type of language input has more of an effect on language learning than Chomsky suggested. CDS is viewed as so important at facilitating language development as it strengthens language processing skills because the children become more efficient at processing familiar words, whereas speech simply overheard by infants, has no effect (Weisleder & Fernald, 2013). However, as evidenced earlier, learning alone cannot facilitate language acquisition. Thus, perhaps an interactionist view should be taken where there is a clear biological drive to learn language, but the child is also an active learner, suggesting whilst our early language experience can be important to our language outcomes, maybe it enhances our innate need for language.
Furthermore, language experiences can also impact our social and emotional outcomes. Regarding social development, individuals diagnosed with developmental language disorder (DLD) are found to have less skilled employment and professions which require a low level of literacy (Conti-Ramsden, Durkin, Toseeb, Botting & Pickles, 2017; Whitehouse, Watt, Line & Bishop, 2009). Additionally, children with a history of language impairment showed difficulty in establishing social relationships (Whitehouse, Watt, Line & Bishop, 2009). This effect on social development has been explained in children diagnosed with Specific Language Impairment (SLI) as a result of them paying more attention the mouth when viewing speech scenes, perhaps due to auditory stimulus requiring more effort for them. This contrasts with typically developing children who shift their gaze between the eyes, for emotional and social information and the mouth for more difficult speech. Consequently, they are able to get more accurate emotion and social cues from the speaker, hence enabling the conditions for healthy relationships to be made and demonstrating one reason why individuals with SLI may not reach optimal social development. Moreover, children with SLI (Girbau-Massana, Garcia-Marti, Marti-Bonmati & Schwartz, 2014) and also healthy people with smaller and more limited vocabulary which has been previously associated with a lack of vocabulary exposure as a child (Rowe, 2012), have been shown to have less grey matter (Lee et al., 2007). Emotional intelligence, which is how we monitor other people’s emotions and take them into account with our own actions (Takeuchi et al., 2010), is correlated with increased grey matter in the brain and also key to aid relationships (Dijk, 2013). If we cannot interpret emotions correctly then we may act in a way which goes against social norms and what is expected of us, thus explaining why language impaired children may suffer with their social and emotional outcomes.
A smaller amount of grey matter in the brain is also associated with general cognitive abilities (Ryman et al., 2016) and so if grey matter is reduced due to a lack of vocabulary, as explained earlier, then it could also be suggested early language experience influences our cognitive development. This is supported by research which shows early language skills and processing speed can predict later variance in cognitive skills at 8 years old (Marchman, 2008). Therefore, we can see why for example, experiencing CDS is so crucial as it can enhance processing speed, and in turn perhaps predict later cognitive development. Early language experience can also enhance cognitive development, especially in that of young dual language learners. Their brains have actually been shown to have a different pattern of response when processing linguistic stimuli than monolingual children, leading to them having greater theory of mind abilities and more competent at tasks with high executive demands. However, research on metalinguistic abilities has shown to be inconsistent, perhaps due to the subjective nature of what is defined as ‘bilingual’ (Barac, Bialystok, Castro & Sanchez, 2014).
Most of the above research, however, focuses on the quantity of language experienced with no comments regarding how the type or quality of language can influence developmental outcomes. One study which achieves this is Rowe (2012) who found the quantity of language experienced positively influences language development only up to 18 months. After 18 months, quality becomes more important than input quantity. At 30 months, language which is rich in diversity and sophistication is key as infants are ready to learn the more complex words. At 42 months, the use of narrative utterances and decontextualized language are key, for example, talking to the child about events which have happened in the past or future. Parents who followed this style had children with larger vocabularies later on in life (Rowe, 2012). This therefore explains how quantity, as well as quality, may be important for developmental outcomes.
Although it is evident early language experience is important to later developmental outcomes, it not be the most important. For example, research has shown it comes hand in hand with socio-economic status (SES) when contributing to development, specifically later language development. Children in low SES families are exposed to an average of 62,000 words per week compared to higher SES families 215,000 per week, demonstrating a difference of 32 million words by the time the child reaches 4 years old (Hart & Risley, 1995). This is explained by upper class mothers producing richer vocabulary with more and longer utterances (Hoff-Ginsberg, 1991). Thus, it may be suggested language quantity is a function of SES which leads to detrimental developmental outcomes. An alternative relationship between language experience and SES is early language velocity (at around 30 months) especially predicts later vocabulary in low SES families (Rowe, Raudenbush & Goldin-Meadow, 2012), suggesting language experience is of more importance in a low SES family. This is supported by research which states although SES is important when caregiver speech is taken into account, this seems to mediate the effect (Huttenlocher, Waterfall, Vasilyeva, Vevea & Hedges, 2010). A reason put forward as to why SES seems to have such a large effect on language development is because high SES caregivers have a better knowledge of child development and so they are able to apply this when raising their young (Rowe, 2008). SES having an impact on later language development also provides further support for the interactionist view of language acquisition as all our language would develop the same if it was just down to biology.
In conclusion, early language experience does seem to influence developmental outcomes, such as language, social, emotional and cognitive development. However, due to conflicting theories of language development and lack of application for case studies, it is still a question as to whether this language experience is driven by a biological drive, solely the environment we are brought up in, or an interaction of the two, although the latter is the most probable. Despite this, other factors may play a more important role in developmental outcomes, such as the SES of the family.