ITP Topic 8 Human Development

Human development is categorised into several predictable periods:

1. Prenatal period: conception to birth (approx. 40 weeks)

2. Infancy: birth to 18-24 months

3. Childhood: end of infancy to ages 10-14

4. Adolescence: end of childhood to ages 18-21

5. Adulthood: end of adolescence until death

Prenatal stages

1. Zygote

2. Embryo

3. Fetus

Prenatal stages

1. Zygote

created at the moment of conception when a sperm unites with an egg. it is the first cell of a new life

Prenatal stages

2. Embryo

from 2 weeks to 2 months. internal systems (nervous system) and organs (heart, lungs, liver, kidneys) begin to form. this is a period of extreme vulnerability to toxins and stress

Prenatal stages

3. Fetus

from 2 months until birth. all organs are formed, and the heart begins to beat. growth and maturation continue until survival outside the womb is possible (as early as 22 weeks with medical intervention)

What happens to cells during early prenatal development?

After about 14 days, cells begin to differentiate, becoming specialized into different types of cells.

Why do embryonic cells develop into different types of cells?

Cells are exposed to different environments/signals, which influence which genes are active and cause them to develop into different cell types.

How does a cell’s developmental potential change as it differentiates?

Totipotent → pluripotent → multipotent → specialized cells (e.g., neurons, blood cells, muscle cells).

Brain development and plasticity

Myelination

the process of insulating nerve fibres with a fatty sheath to increase signal transmission speed. it begins in the spinal cord during the first trimester and on the neurons during the second

Brain development and plasticity

Synaptic pruning

a “use it or lose it” process where the brain preserves used connections and eliminates unused ones. this allows the brain to adapt to its specific environment

Brain development and plasticity

Environmental impact

nutrition, stimulation, and stress (often linked to poverty) significantly affect brain size and complexity. sever neglect can lead to abnormally developed cortical and limbic structures and smaller brain size.

Teratogens

environmental agents that harm the embryo or foetus, disrupting healthy neural development

Teratogen type

Drugs/opioids (the potential effects)

premature birth, withdrawal symptoms (crying, tremors), slow growth, defects

Teratogen type

Alcohol

Fetal alcohol spectrum disorders (FASDs): low birth weight, face abnormalities (small eye openings, thin upper lip), low IQ, and cognitive impairments

Teratogen type

Others: Bacteria, viruses, caffeine

impaired development of language, reasoning, and social behaviour

Prenatal development

Other harmful environmental factors: maternal stress and maternal starvation

• maternal stress: increased vulnerability to anxiety and depression as an adult

• maternal starvation: increased risk of schizophrenia, metabolic and cardiovascular diseases as an adult

Innate reflexes

infants are born with survival mechanisms, including:

• grasping reflex: an ancestral trait from primates for clinging to caregivers

• rooting reflex: turning and sucking when an object touches near the mouth

• sucking reflex: automatic sucking on an object once found

Dynamic systems theory

• Development is a self-organising process that emerges from interactions between the individual and their environment/culture.

• Developmental milestones generally follow a predictable sequence, but their timing can vary depending on environmental and cultural factors.

Infant perception and learning

Visual activity

poor at birth but reaches adult levels by age 1. infants prefect high contrast patterns (e.g. black and white) due to underdeveloped cones

Infant perception and learning

Preferential-looking technique

researchers determine if an infant can distinguish between stimuli by measuring which one they look at longer

Infant perception and learning

What is habituation, and how is it used to study infant perception?

A decrease in response to a repeatedly presented, unchanging stimulus. Researchers use habituation to study what infants can perceive, distinguish, and categorise.

Example: Show a baby the same type of object repeatedly → they gradually look at it less. Then show a new type of object → if their looking time increases, it suggests they notice the difference.

Infant perception and learning

Orienting reflex

the innate tendency to pay more attention to “salient” (novel or unexpected) stimuli

What did the Rovee-Collier Mobile Task show about infant memory?

Infants as young as 2 months can learn that kicking moves a mobile and remember this association. Older infants retain the memory for longer.

What is infantile amnesia?

The inability to remember events from before about age 3–4.

What may explain infantile amnesia?

Possible explanations include:

• Immature brain systems

• Limited language development

• Lack of developed autobiographical memory

What visual preference do infants show early in development?

Infants are predisposed to look at human faces, spending more time looking at faces than many other stimuli.

What do infants tend to imitate?

Infants tend to imitate facial expressions and movements they observe in others.

When do infants begin to show a basic understanding of facial expressions?

By around 3–4 months, infants show a rudimentary understanding of facial expressions.

What is social referencing?

Using another person's facial expression as a cue for how to interpret or respond to a situation.

Attachment

is a strong, persistent emotional connection that is an adaptive trait, increasing an infants chances of survival

How does behavioural theory explain attachment?

Infants become attached to caregivers because caregivers provide food/nutrition.

How does Bowlby explain attachment?

Attachment is innate: infants naturally seek closeness to familiar caregivers for protection and survival.

What did Harlow’s monkey study show?

Infants prefer contact comfort over a caregiver that only provides food, showing attachment is not simply based on feeding.

What is imprinting (Lorenz)?

A rapid form of attachment that occurs during a sensitive period, demonstrated in young birds.

What is Ainsworth’s Strange Situation?

A test of infant attachment based on the infant’s reactions to separation from and reunion with a caregiver.

What are the main attachment patterns of Mary Ainsworth’s strange situation?

• Secure

• Insecure-avoidant

• Insecure-ambivalent

• Disoriented-Disorganized (added later)

The main attachment patterns of Mary Ainsworth’s strange situation

Secure

the child is distressed when the caregiver leaves but is quickly comforted upon their return

The main attachment patterns of Mary Ainsworth’s strange situation

Insecure-avoidant

the child is not distressed when the caregiver leaves and avoids them upon return

The main attachment patterns of Mary Ainsworth’s strange situation

Insecure-ambivalent

the child is inconsolably upset when the caregiver leaves and may both seek and reject contact when they return

The main attachment patterns of Mary Ainsworth’s strange situation

Disoriented-disorganized

added later; characterised by inconsistent or confused reactions

Biological influence in attachment

the hormone oxytocin plays a vital role in social bonding and maternal tendencies, such as nursing

What did Harlow's (1962) research on attachment deprivation show?

Monkeys raised without normal social attachment developed severe social and emotional problems, showing that early attachment and social contact are important for healthy development.

How do nativists, empiricists, and Piaget view cognitive development?

• Nativists: The child is essentially a miniature adult; important abilities are innate.

• Empiricists: The child is like an adult who still has a great deal to learn through experience.

• Piaget: Children are qualitatively different from adults in how they think.

What did Piaget propose about cognitive development?

Children are active learners who progress through four qualitatively different stages of thinking:

1. Sensorimotor

2. Preoperational

3. Concrete operational

4. Formal operational

What are schemes, assimilation, and accommodation in Piaget's theory?

• Schemes: Structured mental frameworks for making sense of experiences.

• Assimilation: Fitting new experiences into an existing scheme.

• Accommodation: Changing an existing scheme or creating a new one to incorporate new information.

What characterizes Piaget's sensorimotor stage?

• Age: Birth–2 years

• Learning occurs through sensory and motor interactions with the environment.

• Major development: object permanence.

What is object permanence?

The understanding that an object continues to exist even when it cannot be seen, independent of immediate sensory or motor interaction with it.

What characterizes Piaget's preoperational stage?

• Age: 2–7 years

• Development of symbolic thinking, such as pretend play.

• Reasoning is largely intuitive and based on appearances.

• Characterized by egocentrism and centration.

• Children generally lack conservation, which develops toward the transition to concrete operational thinking.

What is egocentrism in Piaget's theory?

Difficulty understanding a situation from a perspective other than one's own.

What is centration?

The tendency to focus on one noticeable aspect of a situation while ignoring others, contributing to difficulty understanding conservation.

What characterizes Piaget's concrete operational stage?

• Age: approximately 7–12 years

• Children can think logically about concrete objects and situations.

• They understand reversibility.

• They develop an understanding of conservation.

What is conservation?

The understanding that a quantity remains the same despite changes in its appearance.

What characterizes Piaget's formal operational stage?

• Age: approximately 12+ years

• Development of abstract and hypothetical reasoning.

• Ability to use deductive logic.

• Can form and systematically test hypotheses.

What are the main criticisms of Piaget’s theory?

Later research suggests Piaget underestimated children’s cognitive abilities:

• Object permanence/basic physical understanding appears earlier (Using violation-of-expectation tasks, Baillargeon found evidence of object permanence as early as ~3.5 months)

• Conservation can develop earlier.

• Preoperational children are less egocentric than Piaget proposed.

What evidence suggests infants understand objects earlier than Piaget proposed?

Studies using habituation and violation-of-expectation found that infants around 3.5–4 months understand:

• Hidden/partially hidden objects continue to exist.

• Objects are continuous when partly hidden.

• Two solid objects cannot occupy the same space.

How has research challenged Piaget’s ideas about conservation and egocentrism?

Children can show understanding of number/conservation earlier when tasks are simpler or motivating (e.g., M&M studies), and preoperational children can understand other people’s perspectives better than Piaget suggested.

What did Vygotsky propose about cognitive development?

Cognitive development is strongly influenced by the social and cultural environment. Language is particularly important and eventually becomes inner speech, which helps guide thinking.

It shows that different cognitive abilities change differently with age:

• Vocabulary tends to improve and remain relatively strong with age.

• Processing speed, reasoning, and memory tend to decline with age, especially later in adulthood.

What is Theory of Mind?

The ability to infer and understand the mental states of others, including their beliefs, desires and intentions. It develops early, with some understanding of intentions by around 9 months, and depends partly on maturation of the frontal lobes.

How is Theory of Mind related to prosocial behaviour?

Understanding other people’s mental states supports prosocial behaviour—voluntary actions intended to benefit others, such as helping and sharing.

What are Kohlberg’s three levels of moral reasoning?

• Preconventional: morality based on self-interest and consequences/outcomes.

• Conventional: morality based on social rules, laws and approval from others.

• Postconventional: morality based on abstract ethical principles and values, which may take priority over laws.

Give an example of each of Kohlberg’s levels of moral reasoning.

For whether someone should steal something:

• Preconventional: “He should steal it because he benefits from having it.”

• Conventional: “He shouldn’t steal it because it is against the law.”

• Postconventional: “Breaking the law may be justified if a higher moral principle, such as protecting human life, is more important.”

What is inequity aversion?

An aversion to unfairness. Children may prefer resources to be divided equally even when achieving fairness is costly to themselves. This can contribute to cooperation and social trust.