Table of ContentsView AllTable of ContentsWhen Does the Critical Period Begin and End?The Critical Period Hypothesis—What It StatesWhat Happens to the Brain in the Critical Period?What Kind of Events Impact the Brain During the Critical Period?How Do Adverse Events Impact the Brain?What’s the Difference Between a Critical Period and a Sensitive Period?What Happens to the Brain When the Critical Period Ends?

Table of ContentsView All

View All

Table of Contents

When Does the Critical Period Begin and End?

The Critical Period Hypothesis—What It States

What Happens to the Brain in the Critical Period?

What Kind of Events Impact the Brain During the Critical Period?

How Do Adverse Events Impact the Brain?

What’s the Difference Between a Critical Period and a Sensitive Period?

What Happens to the Brain When the Critical Period Ends?

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The critical period in brain development is an immensely significant and specific time frame during which the brain is especially receptive to environmental stimuli and undergoes a series of rapid changes.

These changes have lifelong effects as essentialneuralconnections and pathways are established, playing a vital role in cognitive, emotional, and social development.

This article will explore the timeline, impacting events, and subsequent consequences of the critical period on brain development. It also explores the distinction between critical periods and sensitive periods and what happens to the brain once the critical period ends.

The Early Years of a Child’s Life

Different aspects of learning and developmenthave different critical periods. For instance, the critical period for language acquisition extends into early adolescence. This means that while the brain is still very good at learning languages during early childhood, it continues to be relatively efficient at it until the teenage years.

The brain is incredibly absorbent during these years, taking in information rapidly. Everything from language to motor skills to social cues is being learned and processed extensively.

Vision Develops During This Period

On the other hand, for certain sensory abilities like vision, the critical period might end much earlier. This means that the brain is most receptive to developing visual abilities in the first few years of life, and after that, it becomes significantly harder to change or improve these abilities.

The brain has a certain time window when it’s exceptionally good at learning new things, especially languages. This window of time is what is referred to as the “critical period.”

Younger People Learn Languages Faster Than Older People

Eric Lenneberg, a neuropsychologist, introduced the Critical Period Hypothesis. He was very interested inhow people learn languages. Through his observations and research, Lenneberg noticed that younger people were much more adept at learning languages than older people. This observation led him to the idea that there is a specific period during which the brain is highly efficient and capable of absorbing languages.

As You Age, It Becomes More Difficult to Absorb New InformationIf the critical period is a wide open window in the early years of life, allowing the brain to take in an abundance of information quickly and efficiently, as time progresses, this window begins to close gradually. As it closes, the brain becomes less capable of easily absorbing languages.

As You Age, It Becomes More Difficult to Absorb New Information

If the critical period is a wide open window in the early years of life, allowing the brain to take in an abundance of information quickly and efficiently, as time progresses, this window begins to close gradually. As it closes, the brain becomes less capable of easily absorbing languages.

This doesn’t mean that learning becomes impossible as you age; it merely indicates that the ease and efficiency with which the brain learns start to decline.

During the critical period, the brain experiences explosive growth. Let’s take a look at some of the changes that happen in the brain during the critical period.

Neurons Form Connections

In the early stages, neurons in the brain start to form connections. These connections are called synapses.

Synapses are bridges that help different parts of the brain communicate with each other. In the critical period, the brain is building these bridges at an incredible pace.

Neuroplasticity Strengthens Brain Connections

Attachment to Primary Caregivers

An essential aspect of the critical period is the development of attachment to caregivers. During the early months and years, babies and toddlers formstrong bonds with the people caring for them.

What Happens When Children Are Not Given Attention?What if a child is not given the attention and care they need during the critical period? This is a significant concern. Without proper attention and stimulation, the brain doesn’t develop as effectively. The bridges or connections that should be built might not form properly. This can lead to various issues, including difficulty forming relationships, emotional problems, and learning difficulties.

What Happens When Children Are Not Given Attention?

What if a child is not given the attention and care they need during the critical period? This is a significant concern. Without proper attention and stimulation, the brain doesn’t develop as effectively. The bridges or connections that should be built might not form properly. This can lead to various issues, including difficulty forming relationships, emotional problems, and learning difficulties.

When a child is given proper attention, stimulation, and care during the critical period, their brain thrives. The connections form rapidly and robustly. This sets the stage for better learning, emotional regulation, and relationship-building throughout life.

When a child is exposed to a rich, stimulating environment where they can play, explore, and learn, it tremendously impacts the brain. Engaging in interactive learning, being read to, and having supportive relationships with caregivers can significantly contribute to a well-developed brain.

Events such as abuse, neglect,head trauma, or extreme stress—collectively known asadverse childhood experiences(ACEs)—can be detrimental to brain development. These adverse events can impede the formation of neural connections and lead to behavioral, emotional, and cognitive difficulties later in life.“Unfortunately, disruptions to normal brain development due to environmental influences such as poverty, neglect, orexposure to toxinscan cause lasting damage. This is why it is so important for children to receive adequate nutrition, stimulation, and parental care during these first few years of life; without it, they may sufferdevelopmental delaysand other issues that could potentially be avoided with proper attention,“Harold Hong, MD, a board-certified psychiatrist says.

When a child is neglected or abused, stress can impact how their brain develops. The parts of the brain involved in emotions and handling stress might not develop properly. This can make it hard for the person tomanage their emotionslater in life.

The hippocampus, involved in learning and memory, and the amygdala, which plays a role in emotion processing, are especially vulnerable.

Similarly, if achild does not have enough food to eator a safe place to live, the chronic stress of these conditions can impact brain development. The brain might focus on survival instead of other important areas of development, like learning and building relationships.

Even accidents that cause head injuries can impact the brain during the critical period. If a child experiences head trauma, it can affect the brain’s development depending on the injury’s severity and location.

It is imperative to distinguish between critical periods and sensitive periods.

For example, while there is a critical period for acquiring native-like pronunciation and grammar, there is also a sensitive period for language learning. Children are more adept at learning new languages when they are young, but even if someone misses this window, they can still learn languages later in life.

One way to visualize the difference is to think of critical periods as a tightly defined window of time with a clear beginning and end, during which certain development must occur. In contrast, sensitive periods are more like a gradual slope, where learning at the beginning is optimal, but the ability doesn’t disappear entirely over time.

It’s essential to recognize that the end of the critical period does not mean the end of learning or brain development. Instead, it signifies a shift in how the brain learns and adapts.

During the critical period, the brain is highly plastic, meaning it can change and form new connections rapidly. As this period ends, the brain doesn’t lose this plasticity entirely, but the rate at which it can make new connections slows down.

The Brain Becomes More Specialized Via Adult Plasticity

The brain also becomes more specialized in the skills and information it has acquired as this period ends. During the critical period, the brain forms numerous connections, and as it ends, it starts to use these connections more efficiently for specialized tasks.

Even though the critical period ends, the brain still possesses a degree of plasticity and continues to learn throughout life.This is called adult plasticity.

Adult plasticity is not as robust during the critical period, but it allows for the continuous adaptation and learning necessary for us to navigate the ever-changing demands of life.

The conventional view is that critical periods close relatively tightly. However, research has started to challenge this rigid view. It’s more accurate to say that the doors of critical periods close but do not necessarily lock.

While the brain’s plasticity decreases after these periods, learning and adaptation can still take place, albeit with more effort and over a longer time. This phenomenon of ‘metaplasticity’—the brain’s ability to change its plasticity levels—remains an exciting area of ongoing research,Dr. Ryan Sultan, a neuroscientist, child psychiatrist, and professor of psychiatry at Columbia University, says.

What This Means For You

4 SourcesVerywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Siahaan F.The critical period hypothesis of sla eric lenneberg’s.Journal of Applied Linguistics. 2022;2(1):40-45.Nelson CA, Gabard-Durnam LJ.Early adversity and critical periods: neurodevelopmental consequences of violating the expectable environment.Trends in Neurosciences. 2020;43(3):133-143.Colombo J, Gustafson KM, Carlson SE.Critical and sensitive periods in development and nutrition.Ann Nutr Metab. 2019;75(Suppl. 1):34-42.Patton MH, Blundon JA, Zakharenko SS.Rejuvenation of plasticity in the brain: opening the critical period.Current Opinion in Neurobiology. 2019;54:83-89.

4 Sources

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Siahaan F.The critical period hypothesis of sla eric lenneberg’s.Journal of Applied Linguistics. 2022;2(1):40-45.Nelson CA, Gabard-Durnam LJ.Early adversity and critical periods: neurodevelopmental consequences of violating the expectable environment.Trends in Neurosciences. 2020;43(3):133-143.Colombo J, Gustafson KM, Carlson SE.Critical and sensitive periods in development and nutrition.Ann Nutr Metab. 2019;75(Suppl. 1):34-42.Patton MH, Blundon JA, Zakharenko SS.Rejuvenation of plasticity in the brain: opening the critical period.Current Opinion in Neurobiology. 2019;54:83-89.

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Siahaan F.The critical period hypothesis of sla eric lenneberg’s.Journal of Applied Linguistics. 2022;2(1):40-45.Nelson CA, Gabard-Durnam LJ.Early adversity and critical periods: neurodevelopmental consequences of violating the expectable environment.Trends in Neurosciences. 2020;43(3):133-143.Colombo J, Gustafson KM, Carlson SE.Critical and sensitive periods in development and nutrition.Ann Nutr Metab. 2019;75(Suppl. 1):34-42.Patton MH, Blundon JA, Zakharenko SS.Rejuvenation of plasticity in the brain: opening the critical period.Current Opinion in Neurobiology. 2019;54:83-89.

Siahaan F.The critical period hypothesis of sla eric lenneberg’s.Journal of Applied Linguistics. 2022;2(1):40-45.

Nelson CA, Gabard-Durnam LJ.Early adversity and critical periods: neurodevelopmental consequences of violating the expectable environment.Trends in Neurosciences. 2020;43(3):133-143.

Colombo J, Gustafson KM, Carlson SE.Critical and sensitive periods in development and nutrition.Ann Nutr Metab. 2019;75(Suppl. 1):34-42.

Patton MH, Blundon JA, Zakharenko SS.Rejuvenation of plasticity in the brain: opening the critical period.Current Opinion in Neurobiology. 2019;54:83-89.

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