Developmental Psychology I: infancy and childhood part 1 Flashcards
What is Developmental Psychology?
It is the study of changes in thought, behavior, reasoning, and functioning across the lifespan.
Example:
A researcher studying how babies develop language skills from babbling to full sentences.
What are Normative Changes?
What are Quasi-normative Changes
What are Idiosyncratic Changes?
Normative: Changes that happen to almost everyone at the same time due to biological or social factors.
📌 Example: Most children begin to walk around their first birthday and start losing baby teeth around age 6.
Quasi-normative: Changes that happen to many people but vary based on personal or cultural factors.
📌 Example: In some countries, children start school at age 5, while in others, they begin at age 7.
Idiosyncratic: Unique, personal changes that not everyone experiences.
📌 Example: A child moving to a new country at age 5 and having to learn a new language and culture.
What is a Life Stage?
A period in human development marked by specific biological, cognitive, and social changes.
📌 Example: Adolescence is a life stage where teenagers go through puberty and develop independence.
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Prenatal stage
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Early childhood: 0-2 years
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Years prior to compulsory schooling: 2-6 years
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Primary school years: 6-12 years
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Adolescence: 12 to the end of the second decade
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Maturity or adulthood: 20 to 65-70 years
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Elderly or old age: from 65-70 years old
What is Maturation?
The biological growth process that happens naturally and allows for orderly changes in behavior.
📌 Example: A baby will eventually learn to sit, crawl, and walk without needing to be taught, because of maturation.
What is Biological (Physical) Development?
The growth and physical changes that occur in the body, including motor skills.
📌 Example: A toddler learning to run, jump, and climb as their muscles and bones strengthen.
What is Cognitive Development?
The development of thinking, learning, memory, and problem-solving skills.
📌 Example: A child progressing from counting on fingers to solving math problems in their head.
What is Psychosocial (Socioemotional) Development?
The development of emotions, personality, and social relationships.
📌 Example: A young child learning to share toys and make friends in preschool.
What is the difference between growth and maturation?
Growth refers to quantitative changes (size, weight, height).
Maturation refers to qualitative changes (brain development, coordination, behavior).
📌 Example:
A child growing from 1.2m to 1.5m is growth.
A baby learning to walk as their muscles and brain develop is maturation.
How does a baby’s weight change in the first two years?
By 4-6 months, a baby doubles its birth weight.
By 1 year, a baby triples its birth weight.
By 2 years, a baby quadruples its birth weight (~12-14 kg).
📌 Example:
If a baby weighs 3 kg at birth, by age 1, they will weigh around 9 kg.
How does the body grow in different stages?
At birth, the head is ¼ of total body length.
The trunk (the part of the body to which the head, arms, and legs connect) grows the fastest during the first year.
From 1 year to adolescence, legs grow rapidly, making up 60% of height increase.
During adolescence, legs and trunk grow rapidly.
By adulthood, legs make up ~50% of total height, while the head shrinks to ~12% of height.
📌 Example:
A baby has a big head compared to its body, but as they grow, the legs stretch out, balancing proportions.
What is cephalocaudal growth?
Growth occurs from head to toe.
The head grows first, then the trunk, and lastly the legs.
📌 Example:
A baby learns to control its head before it can sit, crawl, or walk.
What is proximodistal growth?
Growth moves from the center of the body outward.
Organs form first, then limbs, then hands and feet.
Before puberty, this reverses—hands and feet grow first, then the rest of the body.
📌 Example:
A child first learns to move their arms, then hands, then fingers.
Why are newborn skulls soft?
The neonate skull consists of soft bones called fontanelles, which allow the head to compress during birth.
By 2 years old, the skull bones fuse together.
📌 Example:
If a baby’s skull were completely hard at birth, delivery would be much more difficult.
What happens to bones after birth?
Bones start as soft cartilage and gradually harden (ossify).
📌 Example:
This is why babies can’t stand right away—their bones are too soft.
Not all parts of the skeleton grow and hard at the same rate. The skull and hands mature first.
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Skeletal development is complete by age 18.
Craniosynostosis
is a birth defect in which the bones in a baby’s skull join too early. This happens before the brain forms fully and can slow the baby’s brain growth
How do muscles develop in babies?
At birth, muscle tissue is ~35% water and accounts for ~18-24% of total body weight
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Muscle fibers begin to mature shortly after birth as the cellular fluid in muscle tissue acquires more proteins and salts
Muscle maturation follows cephalocaudal growth (head to toe).
Head and neck muscles develop first, followed by trunk and limbs.
📌 Example:
Babies first hold up their heads, then roll over, then crawl.
How does the brain develop before birth?
The neural tube forms first, then divides into the forebrain, midbrain, and hindbrain.
By birth, all major brain structures are present, but still developing.
📌 Example:
The brain develops like a growing city, with basic roads (brainstem) first, then buildings (cerebral cortex).
Does the brain continue growing after birth?
Yes! The brain develops in stages:
Subcortical areas (basic survival) develop first.
The cerebral cortex (thinking, memory, emotions) develops later.
Primary motor and sensory areas develop by 6 months.
Development of the cerebral cortex allows neonates to over-ride primitive reflexes.
📌 Example:
A baby first learns basic survival reflexes, then later starts recognizing faces and objects.
Can the brain adapt and change throughout life?
Yes! New neurons form in the hippocampus (important for learning and memory). And the olfactory bulb.
Synaptic connections change constantly based on experiences.
📌 Example:
If you learn a new language, your brain creates new pathways for language processing.
Why do newborns have reflexes?
Reflexes are controlled by the brainstem and help with survival.
As the cerebral cortex matures, babies gain control over movement, and reflexes disappear.
📌 Example:
A baby automatically grabs your finger (Palmar Grasp Reflex) but later learns to pick up objects intentionally.
What happens if brain cells don’t migrate correctly during development?
Lissencephaly: The brain doesn’t develop folds, causing severe intellectual disabilities.
Anencephaly: The brain and skull fail to develop, often leading to death.
📌 Example:
If neurons don’t move to the right places, it’s like a house being built with walls in the wrong spots.
🟢 What is the environment in development?
The environment includes everything external that affects an individual’s development.
Types:
Physical factors (e.g., climate, nutrition)
Cultural factors (e.g., traditions, education focus)
Psychosocial factors (e.g., parental support, mental stimulation)
Example: A child in a stimulating environment with books and problem-solving activities will likely develop better cognitive skills.
What was John B. Watson’s perspective on environment and development?
Watson (1930) argued that the environment completely shapes human development.
Quote:
“Give me a dozen healthy infants… and I’ll train him to become any type of specialist, regardless of his talents or ancestry.”
Example:
A child raised in a rich, educated family vs. one in poverty with no education—Watson believed their outcomes would be entirely shaped by their environments.
What is Gesell’s Maturational Theory?
Gesell (1933) believed that development is genetically pre-programmed and follows a biological clock.
Example:
Even if you try to teach a baby to walk at 3 months, they won’t be physically ready. Walking happens when their genes dictate it’s time.
All physical and psychological changes happen due to biological programming.
We have a developmental “clock” that determines when we sit, walk, talk, etc.
Some children reach developmental stages earlier or later based on genetic makeup, not just environmental stimulation.
How do genes and environment interact in development?
Behavioral genetics studies how much genes vs. environment contribute to behavior.
Example:
Twin studies help scientists determine if traits (like intelligence or personality) are inherited or learned.
What do twin studies tell us about genetics and behavior?
🔹 Monozygotic twins (MZ): Share 100% of genes.
🔹 Dizygotic twins (DZ): Share 50% of genes (like normal siblings).
🔹 If MZ twins are more alike than DZ twins in a trait, genetics likely plays a strong role.
Example:
If one identical twin is introverted, the other is highly likely to be introverted too, while fraternal twins may not be.
How do adoption studies help in nature vs. nurture research?
🔹 Adoption studies compare adopted children to their biological and adoptive parents.
Example:
If an adopted child resembles their biological parents in intelligence → genetics plays a role.
If an adopted child resembles their adoptive parents in personality → environment plays a role.
What are concordance rates?
🔹 Concordance rates measure how often both members of a pair (twins, siblings) share a trait.
Example:
Monozygotic twins: Alcohol addiction rate = 80% (40/50 pairs)
Dizygotic twins: Alcohol addiction rate = 60% (30/50 pairs)
This suggests genetics plays a role, but environment also matters (since 20% of identical twins did not develop addiction
Example: If 40 out of 50 identical twin pairs both have alcohol addiction, what is the concordance rate?
A: 40/50 = 80%
What are correlation coefficients?
Correlation coefficients measure the strength of the relationship between two traits.
r = +1.00 → Perfect positive correlation
r = 0 → No correlation
r = -1.00 → Perfect negative correlation
Example:
IQ correlation in twins:
Identical twins: r = +0.86 (high similarity)
Fraternal twins: r = +0.50 (lower similarity)
This suggests genes play a strong role in intelligence.
What is heritability (H)?
Heritability tells us how much of a trait is inherited from our parents and how much is influenced by the environment. It is a number between 0 and 1. We can also create a general measure of how heritable a trait is by calculating the difference between the correlation coefficient of monozygotic twins and that of dizygotic twins = heritability coefficient (H)
Formula:
𝐻 = ( 𝑟identicaltwins − 𝑟 fraternaltwins ) × 2
Example:
H = 0.80 for height → Genes are a major factor.
H = 0.30 for personality → Environment plays a bigger role.
80% of the variation in height is due to genetic factors, while 20% is due to the environment.
H = 0.30 for personality means Personality is more influenced by the environment than by genetics.
How does intelligence heritability change over time? (Wilson, 1978, 1983)
✔ 0–1 years old: No genetic influence on IQ (H = 0).
✔ 18 months old: Genetic influence appears—MZ twins become more alike.
✔ 3–15 years old:
MZ twins stay highly similar.
DZ twins become less similar.
🔹 Conclusion: Genetics becomes stronger over time as individuals choose environments that match their abilities.
Example:
Identical twins may improve their math skills at the same rate, while fraternal twins may drift apart in intelligence.
What is the Canalization Principle? (Waddington, 1966)
Canalization: How much genes restrict development to specific paths. Some traits are strongly influenced by genes, while others are not.
Examples:
Highly canalized trait: Eye color (not affected by environment).
Weakly canalized trait: Intelligence (genes set a range, but the environment determines where in that range you fall).
Example:
No matter how much nutrition you get, your eye color won’t change, but your weight and intelligence can be shaped by diet and education.
What is the Range-of-Reaction Principle? (Gottesman, 1963)
Genes set boundaries, but the environment determines where a person develops within those limits.
Example:
Juan has high genetic potential for IQ. In a poor environment, he still scores above average, but in a great environment, he scores very high.
Tony & Freddie have lower genetic potential. Even in the best environment, their IQ won’t be as high as Juan’s.
How does babbling in infants support the canalization principle?
All infants, even deaf infants, babble the same way → Suggesting strong genetic control
Continuity vs. Discontinuity in Development
✔ Continuity Perspective: Development happens gradually (quantitative change).
Example: A child’s vocabulary expands slowly over time.
✔ Discontinuity Perspective: Development happens in stages with abrupt changes. (Qualitative changes)
We go through stages where we develop new abilities, emotions, and behaviors.
Example: Puberty—one day a child’s voice is normal, and suddenly it deepens.
Give some examples of Discontinuous Development
✔ Freud’s Psychosexual Stages (oral, anal, phallic, etc.)
✔ Erikson’s Psychosocial Stages (trust vs. mistrust, etc.)
✔ Piaget’s Cognitive Stages (sensorimotor, preoperational, etc.)
