Infancy Cognitive Development: Language Development
In utero, the brain develops rapidly, and an infant is born with essentially all of the nerve The growth and body development from infant to child occurs in a . that this gender difference is in part due to children's relationship with their mother. This chapter is a review of what we know about declarative memory development in typically developing infants, and the relations between declarative memory. Much of modern cognitive developmental theory stems from the work of the that all children progress through a series of cognitive stages of development, just as beginning of the infants' understanding of cause‐and‐effect relationships.
Non-declarative memory is apparent virtually from birth. For example, infants show more robust processing of faces they have seen before relative to novel faces. Declarative memory requires conscious recollection and includes the recognition and recall of names, objects, and events. This chapter is a review of what we know about declarative memory development in typically developing infants, and the relations between declarative memory and brain development.
Problems Studying the development of declarative memory and the brain areas that support it are challenging for various reasons. The first problem researchers face is how to reliably measure declarative memory in preverbal children. Traditional tests of declarative memory rely on verbal report, and so are better suited for older children and adults.
Second, it is challenging to link behaviour with the brain.
Infancy Cognitive Development
Researchers must determine whether the timing of changes in behaviour corresponds with the timing of changes in the brain. Last, researchers must make tests that measure behaviour and brain function sensitive to potential deficits. Research Context Infants and young children experience rapid brain development. This is especially true for the areas of the brain that are implicated in declarative memory. The cells that make up most of the hippocampusa brain structure in the medial temporal lobe necessary for the formation of declarative memories, are formed by the end of the prenatal period.
Yet the cells in the dentate gyrus of the hippocampus, an area that links the structure with cortical regions of the brain, do not appear adult-like until 12 to 15 months of age.
The density of synapses in this area increases dramatically at eight months and peaks between 15 and 24 months. Key Research Questions How does long-term memory develop? What behavioural changes are seen in memory performance in infancy and early childhood?
How do changes in memory performance relate to postnatal changes in the brain? Recent Research Results Researchers have used elicited imitation to assess declarative memory in preverbal children. Memory is assessed by comparing the number of actions individual actions and actions in correct temporal order to the number of actions during baseline performance before modeling.
For example, six-month-olds remember actions for 24 but not 48 hours, nine-month-olds remember for one month but not three monthsand by 20 months of age, infants remember for as long as one year.
In addition, with age the effect becomes increasingly reliable—a greater number of infants in each successive age group show evidence of recall see 6 for review.
In general terms, the time course of improvements in memory with age indexed behaviourally is consistent with brain development. Late in the first year of life, the medial temporal lobe structures are functionally mature, and there are increases in the density of synapses in the prefrontal cortex. This corresponds to the improved recall abilities of infants near the end of the first year of life.
Further improvements in the reliability of recall occur throughout the second year of life, corresponding to the continued increases in synapse formation in both the prefrontal cortex and dentate gyrus. More information is needed on the time course of development of memory areas in the human brain.
At the moment, a lot of information comes from animal models rodents and nonhuman primates and so it is unclear how precisely this time course would map onto human brain development. Further work in developmental neuroscience could help to fill this gap. Studies that relate behavioural measures of memory to brain activity are vital to a complete understanding of the development of declarative memory. An advance in this direction comes from research relating event-related potentials ERPs, an electrophysiological technique that measures brain activity associated with specific stimuli to the robustness of behavioural recall in infants.
Conclusions The ability to form memories and remember them is a vital part of human experience.What can we learn from children's peer relationships? - Robin Banerjee - TEDxSussexUniversity
Historically, people believed that infants lacked this ability. The use of a nonverbal task has allowed researchers to challenge and disprove this assumption. Declarative memory is apparent in the first year of life, as evidenced by behaviour or nonverbal, imitation-based tasks. It develops substantially throughout the first and second years of life. The timing of improvements in performance corresponds to the timing of changes in the developing brain.
For example, the rise in synapse production in brain areas implicated in memory roughly maps onto the ages at which we see improvements in recall. Research combining measures of neural processing assessed via ERPs and behaviour assessed via imitation promises to bring greater resolution to the question of relations between developments in brain and in behaviour.
Further work is needed to better understand the development of the human brain and relate it to memory performance in infancy and beyond. Implications This research has theoretical and practical implications.
The Development of Children’s Early Memory Skills
First, the work will inform the adult memory literature—one cannot fully understand the mature end-state of a function without understanding its beginning.
Moreover this research adds to the literature on infantile amnesia. Babies are able to do this because their larynx vocal chords and other parts of their throat change to allow them to make these sounds.
By age 3 to 4 months, babies will add more verbal sounds and start to make the consonant sounds of b, k, m, g, and p. By around age 4 months, babies will begin to put vowel sounds and consonant sounds together to form nonsense words such as "gaga" and "ahpoo" as they start to experiment with how sounds can be linked together.
As well around this age, infants can blow through their lips and may blow bubbles to practice using and controlling their lips and mouths. Babies continue to practice making those sounds, as their brains learn how to interpret and process the communications they hear. By around age 5 months, babies are learning the musical sound and speech patterns of their caregiver's native language, which is the language they hear the most.
Infancy Cognitive Development
As they continue to practice making sounds, they will begin imitating their first sound patterns. Also around this age, babies are using non-verbal cues to communicate their thoughts and feelings to those around them.
They will cling to their caregivers, push them away when upset, and turn their heads when they don't like something. Around age 6 months, they begin to babble. This allows them to connect consonant sounds with vowel sounds in ways that are used in their native language to make distinguishable syllables.
Babbling allows children to imitate the sentence length, intonation, and rhythm of adult speech as they begin to learn how to form verbal thoughts. As babies enter the second half of the first year, their ability to understand how language works and how to communicate continues to become more sophisticated.
By around age 7 months, babies begin taking turns "speaking" with others instead of talking at the same time as others do. They may initiate conversations with others as they begin learning how conversation between people works. Meanwhile, babies will also try to imitate sounds caregivers make, especially animal sounds such as "moo" English for the cow's sound. By around age 8 months, babies begin to connect sounds they and their caregivers make to actual ideas and thoughts that can be universally understood.
For example, when a baby hears the word "milk," she knows she'll be getting her bottle soon; when she says "bub," she'll get her beloved stuffed bear. Also around this age, they build on top of the syllables they started making earlier and now link syllables in more understandable words such as "da-da. Near the end of their first year of life, babies begin to put together all the language lessons they've learned so far. Between the ages of 9 to 12 months, babies begin to say their first real words, such as "mama" and "dada.
By age 12 months, some babies may have as few as a words in their expressive vocabulary, while others may have a dozen.