Child Language Case Studies


Jean Berko (1950)

She carried out experiments with a fictional creature called a 'wug' to see how children understood word endings. 

'This is a wug' ^-^

'Now there is another one. There are two of them. There are two wugs' ^-^ ^-^ 

She found:

  • 4-5 year olds: 76% applied the plural -s ending correctly
  • 5-7 year olds: 97% applied the plural -s ending correctly
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Berko and Brown (1960)

The 'fis phenomenon' 

They described how a child referred to his plastic fish as a 'fis' when the observer responded 'this is your fis?' the child said 'no - my fis' 

He continued to reject the adult's mimicry of his speech until he was told; 'this is your fish'. He then replied, 'yes, my fis'.


The understanding of words and sounds develops faster than children are able to say them

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Social Interactionist Theory

Bruner (1983)

Language Acquisition Support System (LASS) - a system where caregivers support their child's linguistic development in social situations. This includes using child directed speech to help children learn grammatical structures, a wider range of vocabulary and conventions of conversations.

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Critical Period Thoery

Children who are deprived of language interaction early on in their life don't seem to easily aquire it later. 

Lenneberg (1967) proposed the critical period hypothesis, which states that without linguistic interaction before puberty, language development is severly limited. 

The case study of Genie supports this theory, as she was kept isolated until well into her teens and showed little/no language capabilities until extensive time with speech scientists. 

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Case Study: Jim

Importance of interaction

Bard and Sachs (1977) 

Jim was a child of deaf parents, who wanted him to speak normally so didn't teach him much of the sign language they used to communicate with. 

Jim spent a lot of time watching TV and listening to radio, meaning he heard a lot of spoken language. Despite this, his speech was severely impacted until he spent time with a speech therapist. 

Jim was clearly ready to speak, but he needed human interaction and coversation with the therapist in order to become a competent speaker. 

This supports the Social Interactionist Theory

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Child Directed Speech


  • Slower pronounciation 
  • Exaggerated tone
  • Intonation
  • Pauses


  • Simple vocabulary 
  • Diminative forms
  • Personal names
  • Language in child's environment


  • Questions
  • Instructions
  • Repitition 
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Behaviourist Theory

Skinner (1957) - Nurture

He believed that language was just another form of learnt behaviour; the external influences on children determine their use of language. 

He suggested that language was learnt through imitation and reinforcement:

  • Children repeat what they hear (imitation)
  • Caregivers reward a child's effort with praise
  • They reinforce what the child says by repeating words and phrases back and correcting mistakes

Critisisms of this theory:

  • Children can construct new sentences they have never heard of before, so they are not always directly imitating other's speech
  • Imitation can't explain overgeneralisation; children can't copy these grammatical errors because adults don't make them
  • Also can't explain the 'fis phenomenon' - the fact that children can recognise a much larger range of words than they are actually able to use
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Nativist Theory

Noam Chomsky (1965) - Nature

He argued that children are born with an innate capability for language; it is a natural development that occurs when children are exposed to language. He suggested that each child's brain contains a Language Acquisition Device (LAD) which enables them to work out and apply rules from their particular language from the words and structures they hear. 

This theory explains:

  • Overgeneralisation and why they acquire inflections in a certain order - the brain is preprogrammed to do so
  • Common features between langauges known as 'lingustic universals' e.g. everyone uses a combinaion of regular and irregular verbs
  • Why all children pass through the same early stages of language acquisition before refining their range of sounds to their native language
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Zone of Proximal Development

Lev Vygotsky (1978) 

He believed children learn language through support from others. 

Zone of Proximal Development (ZPD) - the idea that the child's carer or teacher models and scaffolds a child's ways of speaking and interacting, so that a child learns how to deal with different social and cultral situations on their own


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Cognitive Theory

Piaget (1973)

This links language acquisition directky to intellectual development. He suggested that children only acquire certain words and phrases once they understand the concept involved.

This thoery expalins:

  • A child can't mentally process the concept that something can exist outside their immediate surroundings (being egocentric). By that, things have object permanence - they can exist all the time, even if the child can't see them. This coincides with a large increase in vocabulary.
  • When the child learns abstract concepts like tenses, they then use the tense associated with each of these
  • Children's semantic mistakes of underextension and overextension because they are to do with mentally categorising things in the world
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