Difficulty: Introductory | Prerequisites: None, though familiarity with basic developmental milestones helps.
This set of notes covers how young children acquire language, what types of words they learn first, and the relationship between comprehension and production in early speech. It also touches on memory types relevant to early childhood and the cognitive underpinnings of early motor milestones like toilet training. These topics sit within the broader developmental psychology framework of the first three years of life. If you are coming in cold, you should know the basics of infant sensory and motor development, as language and cognition build on those foundations.
During a vocabulary spurt, toddlers primarily add nouns to their word bank. Language comprehension outpaces production well beyond age three. Early memory in childhood is not all one type: recalling steps you took in an activity is episodic (autobiographical) memory, not procedural memory.
Vocabulary spurt (word explosion, naming explosion)
A rapid increase in the number of words a toddler produces, typically occurring around 18 months of age. The child moves from learning a handful of words per week to acquiring several new words per day.
In simple terms, this is the point where a toddler's word count takes off sharply.
Nouns (object words)
Words that name people, places, things, or ideas. During the vocabulary spurt, nouns dominate new word acquisition.
Think of it as: the child is labelling the world around them, one object at a time.
Language comprehension (receptive language)
The ability to understand spoken words and sentences. In early childhood, comprehension consistently runs ahead of production.
In simple terms, children understand far more than they can say.
Language production (expressive language)
The ability to generate and speak words and sentences. Lags behind comprehension throughout early childhood and beyond age three.
Procedural memory
Memory for how to do things: motor sequences and skills (riding a bike, tying shoes). It is implicit, meaning you do not consciously recall the steps.
Think of it as: "body memory" for actions you perform on autopilot.
Episodic memory (autobiographical memory)
Memory for specific personal experiences and events. Recalling the steps you took when helping someone bake a cake is episodic, not procedural.
In simple terms, this is your memory of "what happened to me."
Private speech
Speech directed at oneself rather than at a listener, used by children to regulate their own behaviour and thinking. A child talking themselves through a puzzle is using private speech. A reflexive exclamation ("Mmmmm") in response to a stimulus is not private speech.
Think of it as: the child thinking out loud to guide their own actions.
During the vocabulary spurt, the new words children acquire are overwhelmingly nouns.
Verbs, descriptors, and functors (function words like "the," "is") come later.
This pattern reflects how children start by mapping labels onto concrete, observable objects in their environment.
Between ages 2 and 3, language comprehension does not equal language production. Comprehension still outpaces production at this stage.
This gap persists well beyond the toddler years.
A child who says 50 words may understand 200 or more.
Implication for parents and educators: a child who is not yet speaking much may still be understanding a great deal of what is said to them.
Private speech is intentional self-directed talk used to guide behaviour (e.g., a child saying "now I put the red one here" while doing a puzzle).
A reflexive or emotional vocalisation (e.g., saying "Mmmmm" at the sight of ice cream) is not private speech.
The distinction: private speech serves a cognitive, self-regulatory function. A spontaneous reaction does not.
Procedural memory is memory for motor skills and routines performed without conscious recall (e.g., how to walk, how to use a spoon).
Episodic (autobiographical) memory is memory for personally experienced events (e.g., "I helped mummy bake a cake, and first we mixed the flour").
Recounting the steps of a personal experience is episodic memory, not procedural.
This is a common exam-level distinction.
In some cultures (parts of Africa), toilet training begins in the first month of life.
This very early training is related to constant physical contact between mother and infant, not to advanced cognition, muscular control, or specialised training.
The close physical proximity allows the mother to read the infant's cues and respond in time.
Students often think that comprehension and production are roughly equal by age 2 to 3. They are not. Comprehension remains well ahead of production at that age and for some time after.
Students confuse procedural memory with episodic memory. If a child is verbally recounting what they did, that is episodic recall. Procedural memory is implicit, performed without narration.
Students sometimes classify any vocalisation by a child as "private speech." Private speech is specifically self-directed language used to regulate thinking or behaviour. Emotional reactions and reflexive sounds do not qualify.
Students may assume that very early toilet training in some cultures is due to the infants being more physically advanced. The evidence points to constant mother-infant physical contact, not advanced development.
⚠️ The vocabulary spurt word type (nouns) is a high-frequency exam question. Know the answer cold.
⚠️ The comprehension vs. production question is designed to trip you up. The correct answer is that comprehension still exceeds production between ages 2 and 3.
⚠️ Procedural vs. episodic memory: if the question describes a child talking about what they did, the answer is episodic, not procedural. This distinction appears regularly.
⚠️ Private speech requires intentional self-direction. A reflexive exclamation is not private speech.
⚠️ Early toilet training in Africa: the answer is constant physical contact, not cognition or muscular control. This is a distractor-heavy question.
True or false: During a vocabulary spurt, the new words are mostly verbs. (False, they are nouns.)
True or false: By age 3, comprehension and production are roughly equal. (False, comprehension still leads.)
Fill in the blank: Recounting the steps of a personal experience uses ______ memory. (Episodic / autobiographical.)
True or false: A child saying "Mmmmm" at the sight of food is an example of private speech. (False.)
Fill in the blank: Very early toilet training in parts of Africa is linked to constant ______ between mother and infant. (Physical contact.)
Q: When children have a vocabulary spurt, new words tend to be which category: verbs, descriptors, functors, or nouns?
A: Nouns. Children label objects in their environment before acquiring other word types.
Q: True or false: Between 2 and 3 years of age, the child's language comprehension finally equals their language production.
A: False. Comprehension continues to exceed production well beyond age 3.
Q: A child recalls and describes the steps he took while helping his mother bake a cake. Is this an example of procedural memory?
A: No. This is episodic (autobiographical) memory. Procedural memory is implicit and involves motor skills performed without conscious narration.
Q: Grandpa takes a toddler to an ice cream shop. On seeing the ice cream, the child says "Mmmmmmm." Is this private speech?
A: No. This is a reflexive emotional response, not self-directed speech used to regulate thinking or behaviour.
Q: Very early toilet training (first month of life) in parts of Africa appears to be related to which factor?
A: Constant physical contact between mother and infant. It is not due to advanced cognition, advanced muscular control, or specialised training.
The vocabulary spurt connects to broader theories of cognitive development (Piaget's sensorimotor stage, where children learn by interacting with objects, which are the things they name first). The comprehension-production gap is relevant to language assessment and speech-language pathology. Memory type distinctions (procedural vs. episodic) reappear throughout cognitive psychology and neuroscience courses.
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