How does attachment play a key role in infant development ?

From birth to 3 years of life the brain registers the greatest growth across the lifespan, acquiring psychomotor skills, language, cognitive functions such as attention and learning and experiencing rapid social and emotional development. Brain architecture is comprised of billions of connections between individual neurons across multiple areas of the brain. These connections enable fast communication among neurons involved in different functions. In this period,the process of myelination is in place, consisting in coating the axon of each neuron with a fatty coating called myelin which protects the neuron, and helpsit conduct signals more efficiently.

Neural connections form first, followed by more complex circuits that will lead the infant to acquire more advanced abilities over time. The conditions and experiences that young children are exposed to during this period shape the developing brain. The relationships between infants and caregivers build a solid foundation for social, emotional development and future learnings. In the absence of reliable responsive caregiving—the brain’s architecture can be impaired and negatively impact behavioral and emotional learnings.

What are babies’ and toddlers’ main developmental stages?

From birth to 9 months

During this first stage in early life, babies focus on strengthening attachment connections with their caregivers. They secure relationships with their parents and the iterative process in which the adult interacts and synchronize with the baby in a mutual relationship (vocalizing, facial expression, gestures, words) is fundamental to the wiring of the brain.
Infants then use these perceptions to create an initial processing framework for how to engage with others. In other words, the quality of stimulation, care, and interaction as a response to infants’ needs are essential factors that influence child development.

Research has shown that the relationships are prerequisites for future emotional and social skills, as well as language and motor skills acquisition.

From 9 to 18 months

Infants’ communications and motor skills improve tremendously in this period. Babies shift from babbling to expressing their first few words. The words they hear from adults stimulate the language development pathways in the brain. This stage is also an emotional milestone, where they will start to feel separation anxiety and acquire a sense of “self-perception”, acknowledging themselves as individuals.

From 18 months to 3 years

Intellectually, children hold ideas in their minds briefly, engage in pretend play, and become increasingly able to focus their attention on people and objects. Their use of spoken language increases in fast-track learning : an 18 months toddler will use around 20 words and, at the age of 3, he will be able to arrange words in 3-4 words structured sentences. Toddlers also develop perceptual and motor skills that allow them to move, run and climb, thus experiencing a growing awareness of self-control. These emerging skills influence their ability to explore their social environment and lead them to a better sense of independence and responsibility. Also, in this period, toddlers’ daily experiences provide lessons for them to acknowledge their social environment, gain control of impulses and emotions, and learn and adapt to the rules of their family and kindergarten.

The detrimental effect of toxic stress in infants’ development

Brain architecture is associated with the formation of underlying circuits relating to specific abilities. Short-term and moderate stress responses can promote infant development, whereas toxic stress is associated with strong and prolonged activation inducing a physiological response.

Toxic stress in early life is associated with effects on the nervous system and stress hormone systems that can cause inflammation in the body and damage the developing brain architecture. This exposure to chronic adversity in early life can lead to long-lasting health issues impacting learning, behavior, and both physical and mental health.

Research has shown how the developing brain and early life experience are building blocks for future emotions and functional skills such as working, memory, mental flexibility and self-control.


In conclusion, parents and caregivers play a prominent role to develop these skills and opportunities for babies and toddlers to grow up and enhance their skills in the secured places where they live, learn and play. Some ways that adults can help children to build up effective emotional and functional skills are :

  • Respond to their physical and developmental needs throughout early life stages. (Nutrition, sleeping and care)
  • Encourage experiences that promote emotional social cognitive and physical development (playing, exploring, interacting)
  • Increase gradually the complexity of learnings and include the repeated practice of skills overtime helping them to become independent in these learnings and skills
  • Allocate time and space for creativity, learnings and physical exercise
  • Provide a safe environment, protecting them from toxic stress or adverse context


1. Ellis, E. & Thal, D.(2008). Early Language Delay and Risk for Language Impairment. Perspectives onLanguage Learning and Education, 15: 93-100.

2. Barry, R.A., & G. Kochanska. 2010. “A Longitudinal Investigation of theAffective Environment in Families With Young Children: From Infancy to EarlySchool Age.” Emotion 10 (2): 237–49.

3. Bornstein, M.H. 2012. “Caregiver Responsiveness and Child Development andLearning: From Theory to Research to Practice.” In Infant/Toddler Caregiving: AGuide to Cognitive Development and Learning, ed. P.L. Mangione, 2nd ed.Sacramento: California Department of Education.

4. 5 Steps for Brain-Building Serve and Return – Center on the DevelopingChild at Harvard University

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Welcome to "Drop of Science," our captivating video series designed exclusively for parents of young children. With a focus on evidence-based information, each episode  is aimed to inform parents interesting facts about babies that can help improve the whole family’s lifestyle.