November 22, 2021

5 Infant and Toddler Development

By Mihai Simionescu MD By MS
Complexity rating Intermediate
Evidence High Evidence
Read time 8 minutes

It may seem that psychiatry is about disorders. And it is. But no understanding of ‘the abnormal’ is possible without without a reference to ‘the normal’. Over the last several decades we expanded in significant ways our collective understanding of what is ‘normal’ and, likely, we are not at the end of that process. With the realization that we need to use terms as ‘normal’ a bit loose so it does not become oppressive, a solid understanding of normal child development is essential in our line of work.

For the purpose of this series on the Psychiatric Assessment, will try to cover this topic in just four, hopefully manageable, posts. This one will introduce the infant and the toddler and the following three will present the preschool child, the school aged child and the adolescent.

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Infancy describes the period in a child’s life starting at birth and until the beginning of expressive verbal communication. That is about 18 months of age. Toddlerhood follows until 3 years of age. This timespan can be divided in five stages.

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Stage 1 – Prenatal Development

Stage 2 – Infant (0–2 Months)

Stage 3 – Infant (2–7 Months)

Stage 4 – Infant (7–18 Months)

Stage 5 – Toddler (18–36 Months)

 

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Stage 1 – Prenatal Development

 

Obvious elements of inquiry are possible exposures to illness or toxins during pregnancy, rate of maternal weight gain, ease or difficulty of delivery, or immediate postnatal complications.

Less often considered is the “psychological background” of a pregnancy. Throughout the pregnancy, parents have expectations and wishes  for the unborn infant. They build a mental portrait of the baby to come.

One mother may see pregnancy as a burden and the fetus as complication. Another one may see it as a life-changing event that is transforming in a positive way her views of herself and of life in general. 

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Stage 2 – Infant (0–2 Months)

 

The newborn is rapidly achieving homeostasis, or the capacity for maintaining physiological equilibrium, in the face of internal and external stimulation.

Some infants struggle terribly to achieve a state of ‘calm attention’ and any change or stimulation appears to throw them in the deepest despair.

Infants are active learners – visually tracking objects as they move through space, habituating to invariant stimuli, discriminating novelty, and even anticipating caregiver actions.

Some infants are more passive, less curious, less interested. They are likely to learn much slower.

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Stage 3 – Infant (2–7 Months)

 

Infants are strongly motivated or primed to develop attachments with adult caregivers to ensure close, protective, and nurturing contact. This stage sees an increase in the infant-caregiver social reciprocity. 

4Mo – responsive cooing, increasingly differentiated emotional responses, and direct imitation of others’ behaviors → facilitate social interactions.

Some infants are less responsive to the caregiver, appear more ‘self-absorbed’ and less social.

From 4½ Mo –  object permanence (objects and people continue to exist even when they are no longer within sight or sound) + rudimentary cause and effect reasoning (peek-a-boo).

Object permanence is the ability to build mental representations of objects (and people). This allows the baby to soothe oneself with just the memory of her mother. Of course at this age this is very brief in duration. Over the years this can expand and become a critical tool for dealing with frustrations and loss, including the death of dear ones. But the humble beginnings for this ability start here.  

Delays in object permanence and object constancy will greatly affect the capacity to deal with disappointments, with the inevitable delays with which the mother will respond to various needs. Deep despair and intense anger are more likely.

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Stage 4 – Infant (7–18 Months)

 

During this time:

The infant develops a sense of being understood by others. ‘Aha… she understood me’ or ‘oh no… she did not understand’. To be sure, at this age this understanding is not in words, but more like ‘a sense of being understood’. This is early intersubjectivity, an ability that becomes very sophisticated with time. 

Delays in the capacity to ‘read mom’s mind’ and to make her own mind accessible for mom’s reading are associated with a variety of problems at future developmental steps. This capacity is sometimes called ‘Theory of Mind’ and will speak about it elsewhere. 

Basic means–end reasoning, or the capacity to get the sense that this-leads-to-that. From here there is only a step to goal-directed behavior. The infant will point to things, trying to get the adult to do things for her.

Some infants will struggle greatly with making their needs and wants understood. 

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Stage 4 – Infant (7–18 Months)

 

6-8 Mo – separation anxiety –  peaks at about 14 to 18 months and declines thereafter

When it persists well into childhood we call this a disorder. Even a prolonged phase of separation anxiety may be significant in indicating future vulnerability for anxiety states. 

8 Mo – stranger anxiety – peaks at about 24 months, and declines thereafter.

When it persists, it stifles socialization and exploration, important processes for achieving mastery of all kinds.

12 Mo – infants typically first learn to walk →increased independence, a broadening world.

12-18 Mo –  communicative speech. (By 12 months -5-6 words; by 18 months of age, one-word sentences, about 10 words).

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Stage 5 – Toddler (18–36 Months)

 

A ‘newly’ toddler is walking and does some talking. She is increasingly savvy in holding on in her mind and ‘work with’ internal representations of objects and actions. She has a stable, internalized, ‘image of her mother’ that allows her, at least sometimes, to deal with periods of aloneness or with anxiety. She is increasingly capable to do the following:

Deferred Imitation . The behaviors of others are remembered and then practiced later.

Symbolic Representation . Symbols stand for objects. Words are symbols, gestures may stand for objects or actions. In the future the child will use metaphors as symbols to convey more complicated stuff. The use of words marks a qualitative change in the way infants think about the world and interact with others. She can use words, not just images, in her mind, to ‘think about something’. Everything that later we will call thinking relies on that.

Symbolic Play appears as the infant uses a doll to symbolize a baby, and the infant begins to combine words and gestures in order to label objects in  her world or make needs and wants known to caregivers.

Internal Problem Solving begins to replace trial-and-error problem solving, as the infant’s ability to mentally hold and manipulate internal representations increases.

Expressive Vocabulary . By 30 months the infant will speak about 300 words, by 36 months, 500 to 1,000 words.  Three- to four-word sentences become possible.

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