Infancy: Body and Mind

This is Unit Three, part three, on what infants know, how researchers find out, and how language begins. Part two closed on Piaget's six substages, and on a warning that his ages underestimate infants. Part three opens with what later research changed. Carry one question through this part: how much do infants know, and how can anyone tell? An infant cannot answer a question, so every finding here rests on a method. At the entry on how infant minds are measured, the part shows the methods, and why an infant who looks away has learned something. By the end you will be able to explain how Piaget underestimated infants. To describe habituation and preferential looking. To put the early language milestones in order. To compare three accounts of how language is acquired. And to explain what the Romanian orphans show about sensitive periods.

Two entries: what later research changed in Piaget's account, and a famous error in infant searching.

What later research found.

HGD 0352 Piaget Underestimated Infants

Later research found that Piaget underestimated infants. Tasks without reaching show object permanence around four months, when an infant stares longer as a hidden object seems to vanish without cause, and deferred imitation as early as six months. His tasks demanded skills, such as reaching, that infants lacked. His ages are not fixed limits.

A famous error in searching.

HGD 0353 The A-Not-B Error

In the A-not-B error, an infant who has repeatedly found a toy at A keeps searching there after watching it hidden at B, reaching back to the old spot. By seven and a half months infants pass if the delay is under two seconds for reaching, or fifteen for looking.

Four entries on attention and memory, and on the methods that read an infant's mind. The opening question is answered here.

How attention develops.

HGD 0354 Attention in Infancy

Infants spend less than twenty percent of the day alert. Sustained attention grows rapidly in the first year, attentional control begins around four months, and it increases significantly around nine, when an infant can hold focus on a toy through a distracting sound. Attention is an exam keyword under cognitive development.

Evidence that infants remember.

HGD 0355 Infants Remember

In Rovee-Collier's mobile task, a ribbon links a baby's ankle to a mobile, and kicking again after a delay shows the baby remembers: three-month-olds for up to a week, eighteen-month-olds for up to thirteen weeks. Implicit memory is present in infancy; explicit memory is fragile, one reason for infantile amnesia. Infants do remember.

A response that fades with repetition.

HGD 0356 Habituation

Habituation is a decreasing response to a stimulus that is repeated, shown when an infant's looking, sucking or heart rate settles, as when a baby stares at a new picture and then looks away as it is shown again and again. Fast habituation is a sign of efficient processing.

The payoff: how infant minds are measured.

HGD 0357 How Infant Minds Are Measured

Because infants cannot answer questions, researchers read their minds from behaviour, and that answers this part's question. In habituation studies, a stimulus is repeated until the response declines; if a new stimulus revives it, the infant has noticed a difference. In preferential looking, two stimuli are shown side by side, and longer looking shows a preference, usually for the novel one. Heart rate, eye tracking and EEG add further measures. The misconception is that an infant who loses interest has stopped learning. Habituation is itself the evidence that learning occurred, and faster habituation in infancy predicts later intelligence.

Three entries on learning with other people, and on how the home shapes early thinking.

Vygotsky's view of infant learning.

HGD 0358 Vygotsky and Cultural Tools

Vygotsky held that children develop through interaction with caregivers, peers and culture, using cultural tools such as language, counting systems and maps. A toddler builds a puzzle while a parent talks through each step, words the toddler later repeats. The partner's social speech becomes the child's private speech, aloud and then silent.

Learning from other people's reactions.

HGD 0359 Social Referencing

Social referencing is using another person's reaction to decide how to respond, especially in an unfamiliar situation: a baby at a gate glances back at a parent's stern face, then stops. The visual cliff offers the strongest demonstration, as infants check a caregiver's expression before deciding whether to cross.

How home and class shape early thinking.

HGD 0360 Home, Class and Early Cognition

Caregiver education and resources influence infants' language, memory and executive function, and maternal education is among the strongest predictors. In one study at eighteen months, the quality of the home environment outweighed both socioeconomic status and maternal IQ. Poverty harms the developing brain through stress and fewer opportunities; high-quality early care and parent interventions help.

Six entries on language: what it is, and the path from a first cry to two-word phrases.

What language is made of.

HGD 0361 What Language Is

Language is a communication system of words and rules, with infinite generativity. Productive language is speaking or signing; receptive language is understanding. A phoneme is the smallest unit of sound, and English has roughly forty-four; a morpheme is the smallest unit of meaning, so redesigned has three: re, design and ed.

The first sounds.

HGD 0362 Crying and Cooing

Crying is present from birth, with different cries possibly signalling different needs. Cooing, soft vowel sounds, appears by about two months, and a caregiver and a cooing baby take turns, an early form of conversation. That turn-taking comes long before words, and it is part of how language develops.

Babbling.

HGD 0363 Babbling

Babbling, repeated consonant-vowel sounds such as ba-ba-ba, appears around four to seven months and narrows toward the sounds of the languages heard; deaf infants exposed to sign language babble with their hands. The misconception is that ba-ba is a first word. Babbling carries no meaning yet, but more babbling at six months predicts more words at twelve.

Pointing, and the first words.

HGD 0364 Gestures and First Words

Pointing to direct attention appears around nine to twelve months, and first words typically come around twelve months, often a single word standing for a whole thought, as when up means pick me up now. That one-word sentence is a holophrase. English first words are mostly nouns; in Chinese or Korean, more are verbs.

Two common early word errors.

HGD 0365 Over- and Underextension

Overextension applies a word too broadly, as when every four-legged animal is a kitty, even a tiger at the zoo; underextension applies it too narrowly, only to the family cat. Both errors show a child working out a word's boundaries, and both fade as vocabulary grows.

The move to word combinations.

HGD 0366 Telegraphic Speech and the Vocabulary Spurt

Telegraphic speech, two-word phrases such as more cookie, appears at eighteen to twenty-four months, alongside a vocabulary spurt from about fifty to two hundred words by two, and up to a thousand by three, many learned by fast mapping after a single hearing. Receptive vocabulary runs ahead: infants recognise common nouns by about six months.

Three entries: the milestones in order, a popular claim about baby signs, and three accounts of how language is acquired.

The milestones, in order.

HGD 0367 Language Milestones

Early language follows a reliable order. Crying from birth. Cooing by about two months, with early turn-taking. Babbling around four to seven months. Gestures and pointing at nine to twelve months. First words around twelve months, often as holophrases. Telegraphic speech at eighteen to twenty-four months, with a vocabulary spurt to about two hundred words by two and up to a thousand by three. Throughout, understanding runs ahead of speaking, so a child who says little may understand a great deal. The order is similar across cultures, which suggests a biological base, while the ages vary.

A popular claim about baby signs.

HGD 0368 Baby Signing

Baby signing teaches infants simple signs for basic needs, which they can use at six to eight months, as when a seven-month-old signs more at mealtime, and it may reduce fussiness. The misconception is that baby signing boosts language development. Research does not show that it enhances language or cognition.

Three accounts of how language is acquired.

HGD 0369 Three Theories of Language

Three accounts explain how children acquire language. The nativist account, from Noam Chomsky, holds that children have an innate language acquisition device, with experience playing a limited role; Broca's area for production and Wernicke's for comprehension fit a biological basis. The learning account, from Skinner, holds that language is shaped by reinforcement, with Bandura adding imitation. The interactionist account holds that biological readiness interacts with a social environment, because language exists for communication. Learning alone cannot explain language, yet the environment counts: toddlers learn words better face to face than from video. The interactionist view usually answers a question about how nature and nurture combine in language.

Two entries on how infants tune in to the languages around them, one language or two.

How infants tune in to their language.

HGD 0370 The Universal Listener and Child-Directed Speech

Young infants are universal listeners, distinguishing the sounds of all languages, but by ten to twelve months they lose most non-native distinctions. Child-directed speech, with higher pitch, a sing-song rhythm, repetition and long pauses, is preferred from birth, and children who hear it learn words faster. More responsive caregivers have children with larger vocabularies.

Infants learning two languages.

HGD 0371 Bilingual Infants

Children learning two languages from birth reach language milestones at about the same time as children learning one, and bilingual infants distinguish their two languages. A toddler may mix words from both home languages in a single sentence. The misconception is that mixing shows confusion. It does not.

One entry to close the unit: what severe early deprivation does to development, and what recovery shows.

What severe deprivation does to development.

HGD 0372 The Romanian Orphans

Under Nicolae Ceauşescu, Romania's orphanages held many children in conditions of severe neglect, and the consequences showed in language: many children could not produce intelligible words by two and a half. When some were moved into foster care that used evidence-based intervention, their language improved substantially. The same pattern appears in vision, where cataracts removed soon after birth let infants see detail much better. Two readings pull in opposite directions. One treats early deprivation as permanent damage, a door closed for good, and ignores the gains after placement. The other treats recovery as complete, and ignores how far behind the children were at the start. The course holds both halves: severe early harm, and real recovery. That combination fits a sensitive period better than a critical one, the distinction Unit One drew. The exam lists this topic under sensory deprivation.

Look at what you can now do. You can explain that Piaget's tasks demanded reaching, and that tasks without it show object permanence around four months. You can describe habituation, a response that declines with repetition and revives at something new, and preferential looking, where longer looks show a preference. You can put the milestones in order: crying, cooing, babbling, pointing, first words, and two-word speech, with understanding ahead of speaking throughout. You can compare the nativist, learning and interactionist accounts, and say that learning alone cannot explain language. And you can explain what the Romanian orphans show: severe early harm and real recovery, which fits a sensitive period better than a critical one. Unit Four turns to the infant's emotional and social world.