Human Development
Learning Goals
Define human development
Define autobiographical memory and infantile amnesia
Identify the ages that comprise the 4 main periods of human development
Identify and describe research methods, such as longitudinal research designs and cross-sectional research designs, that are used to study developmental changes
Identify and describe the four overarching themes in developmental psychology
Defining Human Development
Development
Changes that occur across the lifespan, from conception to death
It is the examination of continuity and change across the lifespan
How and why do people change over time
Maturation
Learning
Memories
Early memories tend to be vague or non-existent
This failure of autobiographical memory often leads us to believe that our experiences as young infants are less relevant. But this is not the case
Role of culture in infantile amnesia
Autobiographical memory
is shaped by biological, individual, social, and cultural influences.
It also reciprocally influences other aspects of an individual’s behaviour.
4 Main periods of Human development
Prenatal period and Infancy (conception to 2 or 3 years old)
Childhood (2 to 11 years old)
Adolescence (12 yrs old to unknown)
Adulthood (unknown to death
Research Methods in Developmental Psychology
How do we study change over time? Developmental psychologists primarily use two methods:
1. Longitudinal Research Design
In this design, the same group of participants is studied repeatedly over a long period.
Example:
Child A is assessed at 6 months.
Child A is assessed again at 12, 18, and 24 months.
Focus: It tracks individual development and how specific experiences (like listening to classical music) influence that specific child's growth over time.
Pros/Cons: Great for seeing patterns of change, but takes a long time and participants may drop out.
2. Cross-Sectional Research Design
In this design, different groups of people of different ages are studied at the same single point in time.
Example:
Group A (6-month-olds), Group B (12-month-olds), Group C (18-month-olds), and Group D (24-month-olds) are all assessed at once.
Focus: It compares different age groups to see how a variable (like classical music) relates to development across the general population at various stages.
Four Overeaching Themes in Developmental Psychology
Continuity and Discontinuity
Continuity: development proceeds gradually and smoothly over time(like a seedling growing steadily into a tree).
Discontinuity: changes more abruptly from one stage to the next (like a caterpillar turning into a butterfly).
Exp: such as an acorn growing into a mighty oak tree, or a sudden, discontinuous process, such as a butterfly emerging for a chrysalis
Nature versus nurture
In the nature vs. nurture and continuity vs. discontinuity debates, there is no single correct answer.
Some features, like infant temperament, develop gradually and continuously.
Other features, such as rolling over or walking, develop more abruptly and discontinuously.
Nature: Biological factors, such as genetics and heredity, determine who we become.
Nurture: Environmental factors, including upbringing, culture, and social experiences, shape our growth.
Younger children are more similar because they have had less time for genes and experiences to interact.
Older adults differ more because their life experiences have shaped them along different epigenetic paths over time.
Active versus passive
Active: Children are "scientists" who actively explore and influence their environment (e.g., a child’s temperament influences how their parents treat them).
Passive: Children are "sponges" who are shaped by external forces (parents, teachers, media) without playing a role in the process.
Holistic nature of development
Development is not split into isolated "boxes." Cognitive, physical, social, and emotional developments are all interconnected.
Example: A child’s physical growth (learning to walk) affects their social development (being able to move toward a peer to play).
Learning Goals
Identify and describe the 3 stages of prenatal development and the time-period in which they occur
Characterize human perception in utero
Define the term teratogen, identify example of teratogens and explain the effects of teratogens on the developing human organism
Three stages of Prenatal Development
Human experience beings with conception
Prenatal development: period of time before birth
Germinal stage/ Period of the zygote (0-2 weeks)
1st Week Gestation
3 germ layers: ectoderm, mesoderm, endoderm
Ectoderm = nerve tissue and skin
Mesoderm = muscle and bone
Endoderm = soft tissue
Embryonic Stage (3-8 weeks) or embryo
Fetal Stage (9 weeks- birth) fetus
Germinal Stage/ The Period of the Zygote
Ovulation is when an egg is released from an ovary
Fertilization occurs
When sperm meets an egg
In the fallopian tube
During ovulation
Once the egg is fertilized, the germinal stage begins
Time period: First 2 weeks gestation called zygote
During the germinal stage there is
A period of rapid cell division
The blastocyst implants into the wall of the uterus
Embryonic Stage
Embryonic stage: begins when the blastocyst implants into the wall of the uterus
Time period: 3-8 weeks gestation
Week 4 Gestation: Central nervous system differentiated into forebrain, midbrain, hindbrain, spinal corn
Week 7 Gestation: Cells that form the cerebral cortex travel from the lining of neural tube (develop into ventricles of the brain) to their destinations.
Period of growth for major bodily structures are formed, but the embryo cannot yet survive outside of the uterine environment
Stomach, liver and other organs are formed
Fetal Stage
Fetal Stage: 9 weeks gestation to birth
Period of refinements and finishing touches; period of significant growth
Significant advances also occur in brain development
Sensory abilities start to come online in the fetal stage and this is when learning starts to take off
Fetal Stage: Developmental Processes in Brain Development
Significant brain development occurs between week 22 and birth
Much experience and learning occurs during the fetal period because of
Neurogenesis
Myelination
Begins at month 6
Synaptogensis
Synaptic pruning
In late pregnancy and the first 18 months of life, the human brain undergoes rapid grey matter growth.
After this growth spurt, unused cells and connections are removed through a process called pruning.
The brain initially produces more neurons and synapses than needed, keeping only the most useful and active connections.
Can hear noises
Pregnancy last 40 weeks, 8% of babies born premature in canada
Seven months gestation fetus starts hearing
Teratogens
Teratogen: External agents that cause damage or death during prenatal development
Why are the effects of teratogens difficult to predict
Important factors: dose, timing, and cumulative effects
Experiments with humans are unethical
Teratogens affect fetuses the most during a series of critical and sensitive periods
Exert their most negative effects during the period of the embryo
Do most damage during weeks 3 to 8
Embryos exposed to multiple drugs can reduce grey matter thickness
Zygote weeks = prenatal death
Embryonic period = major structure abnormalities
Fetal Period = physiological defects and minor structure abnormalities
Examples of Treatogens
Alcohol
Fetal alcohol syndrome spectrum (FASD)
Includes most serif diagnosis of fetal alcohol syndrome
Thalidomide
used in 1960s to prevent morning sickness
If embryo is exposed to treatagon
Zika virus microcephaly in infants
Phenytoin (Dilantin)
Causes cleft palate
Varicella (chicken pox)
Causes scars and paralyzed limbs
Selective Serotonin Reuptake inhibitors (prozac)
Autism
Aspirin
Slow growth
Acetaminophen
High risk for ADHD
Tobacco
Underweight, physical and physiological problems
Research Methods
Can’t ask babies questions so use behavioural measures
High amplitude sucking paradigm
Sucker is connected to wire
Connected to a computer
Computer measures number of sucks
Baby presented to stimuli (exp. Hearing a sound)
The computer measures baseline sucking when given stimuli does the rate of sucking change
Exp. There is an increase in sucking more when they have a good preference for a sound
In this example when baby sucks harder they can hear a sound
Habituation paradigm
Can an infant discriminate between 2 stimuli
Can the infant discriminate between two stimuli
Starts by showing an infant stimuli repeatedly until they are bored and look away
When the baby is bored from looking its called habituated
Once habituated a new stimulus is shown and they are gonna be interested in the new stimulus as the baby looks longer and this is called dishabituation
If the baby couldn’t discriminate they will stay habituated
Genetic Risks to Development
Modern technology allows the screening of embryos for every known mutation. This raises a massive ethical debate regarding the cost vs. benefits of choosing which embryos to keep based on their genetic code
Genetic abnormalities are more common in children of older parents
A woman is born with all her immature eggs. An egg in a 40 year old woman has been exposed to 40 years of environmental toxins/ influences before its final division
Men produce new sperm roughly every two months, meaning the cells have much less time to be exposed to harmful environmental factors
Down Syndrome (Trisomy 21)
Cause: faulty cell division results in a third copy (full or partial) of the 21st chromosome
Impact: results in intellectual disability, mild physical abnormalities, and a shortened lifespan (typically 40-50 yrs)
Risk increases exponentially with maternal age
Age 20: 1 in 2,000 chance
Age 45: 1 in 30 chance
Babies triple their birth weight within the first year
Newborn head is ¼ the size of total height in adults is ⅛
Trunk in newborns and adults is ⅜
Refusal to make eye contact in infancy is often linked to the late development of social and language impairments
Learning Goals
Describe major patterns in infants' perceptual development and explain how it is measured.
Describe major patterns in infants motor development and discuss cross- cultural differences in motor milestone and achievement
Describe infants and children's cognitive development.
Explain Piaget's theory of cognitive development
Describe the examples of False Belief Tasks.
Perceptual Development
Infants begin perceiving in utero, but the complexity increases dramatically after birth.
Sensation: The raw input from sensory organs.
Perception: The organization and interpretation of sensory information into a coherent understanding (e.g., humans organize sounds into language, whereas dogs perceive the same sounds differently)
How do we measure perception in infants
Unlike adults, who provide verbal reports, infant perception is measured via:
Preferential Looking Paradigm: Measuring "looking time." Infants naturally look longer at stimuli that are interesting, stimulating, or familiar.
Grating Visual Acuity Test: Used to determine how well an infant can distinguish between fine lines (striped vs. solid) to measure visual sharpness.
Babies and late-term fetuses have a preference for human faces
Visual Acuity Milestones
At Birth: Eyes are the least developed sense. Babies can only see a few inches away (conducive to bonding during breastfeeding). Acuity is approximately 20/400.
1 Month: Acuity improves to 20/120.
6 Months: Infants reach adult-like acuity. Color and depth perception also fully develop during this window.
Babies prefer looking at large, high contrast, colorful objects
Motor Development in Infancy
Newborn motor skills are primarily driven by involuntary reflexes.
The newborn stage lasts from birth to 28 days.
Newborns spend 16-18 hours sleeping big part is REM sleep
2 to 3 hrs of crying a day
Wakefulness: looking around and physical movement of arms and legs
Neonatal Reflexes
Clinical Note: While some reflexes (swallowing, coughing, blinking) last a lifetime, many should disappear as the infant grows. If they persist, it may indicate issues with Central Nervous System (CNS) development.
Rules of Motor Development
Cephalocaudal Rule: Development moves from "top to bottom" (head control before walking).
Proximodistal Rule: Development moves from "inside to outside" (center/organs before periphery/fingers).
Cultural Differences & "WEIRD" Research
Variation: Motor milestones are not universal. Kenyan infants often walk at 7–11 months (encouraged by mothers), whereas Canadian infants walk closer to 12 months.
Important to consider behaviours inside their context of social relationships and culture
The "WEIRD" Problem: Much psychological data comes from Western, Educated, Industrialized, Rich, and Democratic populations, which is not representative of the global population.
Piaget’s Theory of Cognitive Development
Piaget viewed children as constructivists - active explorers who build their own understanding of the world.
The Mechanism of Learning
Children organize knowledge into Schemas (mental frameworks).
Assimilation: Adding new information to an existing schema.
Example: A child learns that a hawk is a bird because it has wings, feathers, and can fly.
Cognitive Disequilibrium: The discomfort felt when new information contradicts a schema.
Accommodation: Modifying the schema to fit new information, returning to Equilibrium.
A kiwi is a bird but cannot fly, so the child adjusts the bird schema to include exceptions.
The Four Stages
Criticisms of Piaget’s Theory
Cognitive development may be more gradual and variable than Piaget suggested.
Some adults do not consistently use abstract reasoning.
Piaget may have underestimated young children and overestimated adolescents.
He did not clearly explain how children move between stages.
His theory gave limited attention to social, cultural, and family influences on development.
Lev Vygotsky’s Theory
Lev Vygotsky emphasized the role of culture and social interaction in cognitive development.
Unlike Jean Piaget, Vygotsky believed cultures teach children both what to think and how to think.
Children learn through interactions with parents, teachers, peers, and the community.
Role of Language
Language helps children communicate and learn socially.
Self-directed speech later helps with problem solving and develops into inner speech.
Zone of Proximal Development (ZPD)
The ZPD is the range of tasks a child can complete with guidance from more knowledgeable others.
Learning is most effective when tasks are challenging but achievable with help.
Scaffolding
Scaffolding involves giving support that matches the child’s needs.
Adults provide guidance when needed and gradually reduce help as the child becomes more capable.
Circular Reactions
Primary circular reactions (1–4 months): repetitive actions involving the infant’s own body (e.g., sucking fingers).
Secondary circular reactions (4–8 months): repetitive actions involving external objects (e.g., kicking a mobile).
Tertiary circular reactions (around 12 months): trial-and-error experimentation (e.g., repeatedly dropping objects).
Information Processing
Overview: Information processing models extend Piaget’s theory by describing specific changes in a child's reasoning abilities.
Processing Speed: Overall processing speed increases throughout childhood. For judgment tasks, adults are 3x faster than 4- to 5-year-olds, and 2x faster than 8- to 9-year-olds.
Attention:
Focused Attention: By elementary school, the ability to focus and ignore distractions reaches adult levels.
Sustained Attention: The ability to maintain focus over time remains limited until age 11, after which attention span increases yearly until adulthood.
Memory Development: Memory abilities change dramatically after age 2, driven by brain maturation.
Brain Structure: The amygdala and most of the hippocampus mature early (around 6 months). Frontal lobe and further hippocampal development in the third year enable long-term memory formation, especially for event sequences.
Autobiographical Memory: Between ages 3 and 5, improved memory and a growing sense of self combine to form the first autobiographical memories.
Naïve Theories
Challenge to Piaget: Piaget believed object understanding develops slowly, but contemporary psychologists disagree.
Early Understanding: Very young children understand a great deal about objects and physics before having much physical experience with them.
Infant Cognition: Infants as young as a few months old demonstrate this understanding by looking longer at "impossible situations" (e.g., a toy mouse failing to appear between two blocks where it should be visible).
Temperament
Definition: A child's prevailing patterns of mood, activity, and emotional responsiveness. These initial dimensions predict adult personality.
Rothbart’s Three Categories of Temperament (2007)
Surgency / Extraversion: Degree to which a child is happy, active, vocal, and social.
Negative Affect: Proneness to anger, fear, sadness, and frustration; degree to which a child is shy and difficult to soothe.
Effortful Control: The ability to pay attention and inhibit behavior.
Gene-Environment Interactions
Parenting and Temperament: Temperament shapes how children interact with their environment and caregivers, but parenting also alters outcomes.
Example: Fearful children develop a stronger internal sense of right and wrong when raised by gentle parents rather than punitive ones.
The Rhesus Monkey Study (MAOA Gene): Demonstrates biological and evolutionary contributions to temperament based on rearing environment.
Low-activity MAOA gene: Monkeys are typically more aggressive and dominant only when raised normally by their mothers.
High-activity MAOA gene: Monkeys become the more aggressive ones when raised in peer groups without mother contact.
Goodness-of-Fit: This research supports the "goodness-of-fit" model (Thomas & Chess; Rothbart), which states that development is shaped by the compatibility between a child's temperament and their environment.
Cultural Socialization
Cultural Values: Temperament interacts with large-scale cultural expectations.
Individualistic Societies (e.g., North America): Highly value and encourage social initiative.
Collectivistic Societies (e.g., China): Highly value and encourage self-control.
Impact: Two children with identical temperaments and behaviors will receive different feedback and interpretations from peers and adults depending on their culture's values.
Theory of Mind
As children develop, they acquire a Theory of Mind: the understanding that human behavior is guided by mental representations and that these representations (beliefs) differ between individuals.
It elaborates on Piaget's concept of egocentrism (a young child's lack of awareness of others' viewpoints).
Utility: It serves as an important tool for tracking both typical and abnormal psychological development.
Evolutionary Origins:
Premack & Woodruff (1978) originally argued that human theory of mind extended from similar abilities in apes, though others claimed it was uniquely human.
Recent eye-tracking research (2016) supports Premack’s original view, showing evidence of TOM-like abilities in apes.
The False Belief Task:
The classic method to test for TOM is the "Sally–Anne" task.
Scenario: Sally puts a ball in a basket and leaves. Anne moves the ball to a box. Sally returns.
Result: Children who have developed a TOM understand that Sally lacks their knowledge of the move, and they will correctly predict that Sally will look for the ball in the basket.
Timeline: Developmental psychologists generally agree that TOM emerges between 3 and 4 years of age (earlier than the end of Piaget’s preoperational stage).
Building Blocks of Theory of mind:
Joint Attention (First Year): Following another person’s gaze and pointing to direct someone else's attention.
Object Distinction: Developing the ability to distinguish between living and nonliving objects.
Intentionality (By Age 3): Distinguishing between intentional and unintentional behaviors (e.g., 3-year-olds will only imitate intentional actions).
Social and Clinical Importance:
TOM is critical for healthy social development.
A failure to develop a typical TOM is closely linked to autism spectrum disorder, which is characterized by extreme social difficulties.
False Belief Tasks
These tasks test whether a child understands that someone else can hold a belief that the child knows to be untrue. This marks the transition from egocentric thinking to understanding the mental states of others
Example: An adult asks a young child (for example, a three-year-old), "What do you think is in this box?" The child replies, "Smarties," because they recognize it as a Smarties box. The adult then asks, "Why don't you open the box and see?" Upon opening it, the child realizes the box actually contains pencils. The adult then closes the box and asks, "What do you think your friend Jenny would say is in the box if she saw it?" The child replies, "Pencils."
Human development involves a longer period of dependency than in other primates.
Physical abilities seen early in other primates, such as independent movement, take about one year to develop in human infants.
Sex refers to physiological characteristics, mainly defined by XX (female) and XY (male) chromosomes.
Gender refers to psychosocial aspects along the maleness–femaleness continuum.
Development is a cascade of hormonal, structural, and behavioural events influenced by phenotype.
Androgen Insensitivity Syndrome (AIS): a genetic male whose body cannot respond to male hormones (androgens).
5-Alpha-Reductase Deficiency: a rare condition affecting hormone conversion.
Congenital Adrenal Hyperplasia (CAH): a condition in which a fetus is exposed to excess male hormones.
Newborns can distinguish between pleasant smells and recongize their moms smell
Newborns can distinguish between sweet, sour, salty
Newborns prefer sweet
Learning Goals
Describe infant Social Development
describe the procedure for the strange situation
identify and describe individual differences in the four types of attachment styles
characterize changes in self-esteem across the lifespan
describe the principal components of identity formation according to Erik Erikson
describe the cognitive and Social Developmental Milestones that occur during adolescence
identify the major life milestones in adulthood
understand research examining today's false beliefs about aging
discuss changes in memory,attention, emotion and relationships across adulthood
identify and describe the three life crisis that adults face in adulthood according to Erikson's psychosocial Theory
Social Development
Piaget describe the transition from egocentrism to sociocentrism.. and infants are indeed more egocentric than older children
but the sociocentrism of humans is one of our most defining features even from birth
like some other animals human children form bonds with their caregivers
this emotional bond is called attachment
it is an essential part of healthy human development
attachment is critical for physical and biological development
Significant bonds are formed between caregivers and their young
Imprinting
The Experiment: Konrad Lorenz split geese eggs into two groups. One hatched with the mother; the other hatched in an incubator with Lorenz as the first moving object they saw.
Result: The incubator geese followed Lorenz everywhere, even into adulthood, ignoring their biological mother.
Takeaway: Imprinting is a biologically programmed, instinctual drive to bond with the first large moving object seen after birth.
Biological needs
Harry Harlow challenged the "Cupboard Theory" (the idea that infants only love mothers because they provide food).
The Experiment: Rhesus macaques were given two surrogate mothers:
Wire Mother: Cold, but provided milk.
Cloth Mother: Soft and warm, but provided no food
The Findings:
Monkeys spent 16 to 18 hours a day on the cloth mother.
They only visited the wire mother to eat, then immediately returned to the cloth mother.
Fear Response: When startled by a mechanical "monster," they ran to the cloth mother for security.
Key Takeaway: "Contact comfort" (warmth/security) is more vital for attachment than nourishment.
Ethical Note: These monkeys suffered permanent social damage, leading to modern ethical restrictions on isolation studies.
Monkeys spent 16 to 18 hours a day on the cloth mother.
They only visited the wire mother to eat, then immediately returned to the cloth mother.
Fear Response: When startled by a mechanical "monster," they ran to the cloth mother for security.
Real world Example
Punch the monkey who lives in a zoo in Japan
experienced abandonment from his mother and rejection from older higher status monkeys
the zookeepers gave punch of stuffed animal for comfort
in March punch made a friend named gochan and Momo Chan
the stuffed animal gave him a form of attachment and comfort in his early months
Individual differences in attachment
All infants require an attachment figure for normal development
There are major and individual differences in how infants attached to their caregiver or caregivers
Secure Base: extent to which an infant uses their caregiver
How the infant reacts to reunions with their caregiver after short separations
Mary Ainsworth developed the Strange Situation Procedure to operationalize and measure these variables
Strange Situation Paradigm
Securely attached infants may become upset when left with the stranger (or when left alone)
Ainsworth proposed that infants can be securely or insecurely attached to their caregivers
An infant's attachment style predicts many outcomes in adulthood such as:
Academic achievement
Emotional health
Relationship quality
Self-esteem
Parenting Styles Matrix
Parenting styles are categorized into four quadrants based on two primary dimensions: parental support (warmth, empathy, and responsiveness) and behavioural regulation (supervision, discipline, and expectations).
1. Authoritative Parenting (High Support + High Regulation)
Characteristics: Considered the ideal approach. Parents are consistent, firm, warm, and reasonable. They set age-appropriate limits and educational (rather than punitive) consequences. Standards are clearly communicated, and feedback is welcome, though parents remain in charge.
Outcomes: Consistently linked to the most superior psychological and social outcomes in children.
2. Authoritarian Parenting (Low Support + High Regulation)
Characteristics: Prepares children well for societal limits but lacks necessary warmth. Parents have a higher tendency to use harsh and physical punishments.
Outcomes: Less-than-ideal for contemporary environments; lower levels of warmth and a greater tendency to prompt rebelliousness in children.
3. Indulgent Parenting (High Support + Low Regulation)
Characteristics: Warm and loving, but unable or unwilling to set boundaries or say "no." They prefer to let outside forces (teachers, law enforcement) establish rules.
Outcomes: Children are monitored less and display higher levels of antisocial behaviour compared to authoritative or authoritarian peers.
4. Uninvolved / Neglectful Parenting (Low Support + Low Regulation)
Characteristics: Typically only occurs when severe disruptions exist within the family unit (e.g., severe illness, psychopathology, marital discord, or substance abuse).
Outcomes: High risk for negative outcomes. By Grade 12, children of uninvolved parents drink and smoke nearly twice as much as those from authoritative/authoritarian homes, and sons face a very high risk of antisocial behavior.
Dynamics, Culture, and Historical Shifts
Fluidity and Consistency
Style Adaptability: A parent's style is not static. Radical shifts in life circumstances—such as job loss, divorce, or illness—can temporarily throw a competent parent off balance.
Parental Alignment: Most couples share a common parenting style. If styles differ, the presence of one authoritative parent serves as a protective buffer against the negative outcomes associated with the other styles.
Cultural Differences
Canadian Parents: Viewed as more generally accepting of child behaviour and equally tolerant toward both daughters and sons.
French & Italian Parents: Perceived to enforce significantly stricter behavioral norms for daughters compared to sons.
Italian Families: Adolescents report high levels of emotional closeness alongside higher levels of family conflict.
Historical Shifts
Generational Trends: Modern parents (compared to their own parents) show an increase in positive development metrics, such as higher rates of daily reading and a decline in reporting the use of spanking.
Home vs. Community Autonomy: Over the past century, Western children have gained more freedom inside the home (e.g., voicing dissenting opinions) but have lost significant independence outside the home (e.g., unsupervised travel to a neighborhood playground).
Infant Attachment Styles
Secure Attachment
Adjusts calmly to the parent leaving and returning
Insecure- Resistant Attachment
Holds onto parent to prevent seperation
Possibly from inconsistency in attention and is an interminable response, often described as clingy
Children are never truly comfortable. They show immense distress when the mother leaves, but act alternately clingy and rejecting/angry when she returns.
Insecure - Avoidant Attachment
Shows little interest when the parent leaves or reappears
Children show no distress when the mother leaves, interact comfortably with the stranger, and do not immediately approach the mother when she returns.
Disorganized Attachment
Wants to be close to but also away from parent
Attachment
Infant Closeness: Due to extreme physical dependency, maintaining closeness to a caregiver is a high priority for human infants. They use behaviors like smiling, cooing, and crying to secure adult attention.
Harlow’s Rhesus Monkey Studies (Contact Comfort)
The Debate: Freudian and behavioral theories of Harlow's era claimed infant-mother bonding was based strictly on feeding (pleasure from feeding or positive reinforcement with food).
The Experiment: Harry Harlow isolated newborn rhesus monkeys and gave them two surrogate mothers: a bare wire mother and a soft cloth mother. Both could be equipped with a milk bottle.
The Findings: Monkeys spent the vast majority of their time clinging to the cloth mother, running to her immediately when threatened by a scary toy. They only visited the wire mother to feed, leaving as soon as they were full.
Conclusion: The Freudian and behavioral focus on feeding was incorrect; a mother's ability to provide contact comfort is the critical factor in forming attachments.
Mobility and the Timing of Attachment (Bowlby)
Evolutionary Foundation: John Bowlby noted that the timing of attachment is tied to an animal's mobility. Birds (mobile at birth) attach immediately. Human infants (immobile early on) have more time to bond.
Milestones (6 to 8 Months): Around the time human infants begin to crawl, they show clear signs of bonding via two developmental milestones:
Separation Anxiety: Distress shown when separated from their primary caregiver.
Stranger Anxiety: Crying and distress around unfamiliar people, signaling an important social step forward as infants recognize who belongs in their world.
Ainsworth's "Strange Situation" and Attachment Types
Mary Ainsworth developed the Strange Situation protocol, observing through a two-way mirror how infants reacted to a sequence of separations and reunions with their mothers and a friendly stranger.
Cultural Differences in Attachment
Attachment frequencies vary across cultures due to differing parenting norms:
Japan: Similar proportions of secure attachment to North America, but higher rates of anxious-resistant attachment and virtually zero avoidant cases.
Germany: Similar rates of anxious-resistant attachment to North America, but significantly higher rates of avoidant attachment.
Parenting Style and Ecological Adaptation
Responsive Parenting $\rightarrow$ Secure Attachment: Parents who meet needs promptly teach children the world is predictable. This security gives children the confidence to explore their environment (an expanding "radius of exploration").
Unresponsive/Inconsistent Parenting $\rightarrow$ Insecure Attachment: Teaches children the world is unpredictable. Counterintuitively, ignoring a child's needs results in more clinginess and constant attention-seeking, as they learn they must persist to get a response.
The Ecological View: Secure attachment is ideal in safe societies where exploration is low-risk. In dangerous environments, an insecure attachment style—which keeps the child highly vigilant and close to the parent—may actually be a more realistic, adaptive survival strategy.
Self-Esteem in Early Childhood
Self esteem: What do individuals think about themselves
How do young kids describe themselves
In physical terms
Almost always positively ( Positivity Bias)
Example: kids think they are the best at everything
Self- Esteem in School-Aged Children
Positivity Bias (the tendency for young children to overestimate their abilities) declines during school age due to:
Social Comparison: Children begin to evaluate their own abilities against those of their peers.
Cognitive Growth: Increased cognitive skills allow children to understand that others hold different perspectives.
Curriculum-Based Comparison: Perspective-taking increases as children are measured against standardized academic milestones.
Objective Evaluation: School environments introduce objective grading and competitive settings (such as team-based sports), which provide realistic feedback on performance.
Self- Esteem Across Development
Young children have high self-esteem
Adolescents have lower self-esteem
Particularly true for women
Adults gain self-esteem gradually throughout development
There is a marked decline in older age.
Mean-level change: follows a particular curve but might not be true for a singular individual
Self- Esteem Consistency
Compared to others and individuals self-esteem is relatively consistent across the lifespan
Much variability in self-esteem is due to hereditary
Identical twins self esteem correlates to a greater degree than non twin siblings self esteem
Rank-order stability
Children with lower self-esteem tend to have lower self-esteem as adults
Erik Eriksons and Identity Formation
Psychosocial Theory of Development : Theory of conflicts and resolutions that occur throughout the lifespan
Believe that identity formation was the chief task of adolescence
Conflict: identity versus role confusion
Resolution: Identity achievement
Infancy: Trust versus mistrust
Early childhood: autonomy versus shame and doubt
Presschool: initiative vs guilt
School age: industry vs inferiority
Adolescence: identity vs confusion
Young adulthood: intimacy vs isolation
Middle adulthood: generativity vs. stagnation
Matury: ego vs despair
Identity Formation
Identity diffusion (role confusion)
Unable to make any decisions about identity
Identity foreclosure
Prematurely deciding on identity
Psychosocial Moratorium
Identity crisis; unable to make a choice regarding identity
Identity achievement
High exploration and commitment to identity. Stable sense of identity
Challenges and Achievement in Adolescence
Emergence of abstract thinking.
Personality traits become more important
Emergence of self-socialization
Friends and social groups become of paramount importance.
Youth are more likely to participate in risk-taking behavior if peers are present
Adolescent egocentricism:
They are more self-centered
They are more self-aware and self-conscious
Personal Fable
They think they are unique in their experiences
They think they are invulnerable to risk taking behaviours
Example: if i take the drugs it will not affect me
Imaginary Audience
They think everyone is watching them
An Artificial Period: Adolescence is a relatively recent, culturally defined phenomenon.
In historical hunter-gatherer societies, sexual maturity at puberty marked immediate entry into adult roles, responsibilities, and privileges.
The word puberty originates from the Latin word for "adult."
Vague Boundaries: While adolescence begins clearly with the biological onset of puberty, its endpoint is socially determined. Financial independence, moving out, marriage, and parenthood define the end of adolescence far better than a specific chronological age.
Factors Extending Modern Adolescence
Modern industrial societies experience an extended period of adolescence because it now starts earlier and ends later due to two primary factors:
1. Declining Age of Puberty (Biological Shift)
The biological onset of physical maturity has dropped dramatically over time.
Boys: The average age of puberty onset dropped from 11–12 years of age down to an average of 10 years old (with signs appearing as early as age 9).
Girls: The first signs of puberty can now begin as early as 8 years old.
Menarche: In Canada and globally, the average age of menarche (the first menstrual period) has consistently declined.
2. Prolonged Societal Preparation (Economic Shift)
Technological and modern societies require an extended period of education and specialized training.
Because of this, youth reaching biological puberty are not yet equipped or permitted to assume adult working roles in modern economies, creating a gap between biological maturity and social adulthood.
Research Context: Residential Schooling and Substance Use Among Indigenous Peoples
Background: Individuals who experience childhood neglect and abuse face lifelong negative psychological effects and a heightened risk of substance abuse.
The Canadian Context: The residential school system forcibly separated thousands of Indigenous children from their families to strip them of their culture, family ties, and identities. Conditions were often poor, with widespread reports of physical, emotional, sexual, and verbal abuse.
The Study: Researchers in Quebec examined the associations between residential school attendance, childhood abuse, and substance abuse within an Indigenous population (Ross et al., 2015).
Research Design
The Question: Within an Indigenous community, are individuals who attended a residential school and/or experienced childhood abuse more likely to face drug and alcohol problems?
Methods: Interviews were conducted with 358 participants to gather data on:
Residential school attendance and experiences.
Alcohol and drug use/abuse.
Sociodemographic information.
Experiences of physical or sexual trauma before age 18.
Ethics: The study respected Indigenous cultures and traditions by involving community members at every stage of the research process. Most research assistants responsible for data collection were members of the community.
Results and Statistics
Out of the 358 participants surveyed:
Attendance: 28.5% ($n = 102$) attended residential schools.
71.1% of attendees believed it had a negative impact on their lives.
The most frequently reported negative experiences were isolation from family, followed by verbal or emotional abuse.
Abuse Rates: 35.2% (n = 121) reported childhood sexual abuse; 34.1% ($n = 117$) reported childhood physical abuse.
Substance Associations:
Alcohol: Residential school attendance was significantly associated with alcohol problems, even after controlling for age, gender, and childhood abuse.
Drugs: Experiencing physical or sexual abuse before age 18 was associated with drug abuse. Residential school attendance itself was not directly associated with drug abuse.
Conclusions
Abuse Impact: Childhood physical and sexual abuse were prevalent among participants and correlated with a three-fold increase in the likelihood of drug abuse.
School Attendance Impact: Residential school attendance carried a substantially higher risk of alcoholism, independent of whether the individual experienced direct physical/sexual abuse.
Broader Implications: The researchers emphasize that understanding current Indigenous experiences requires deeper investigation into trauma, specifically the cumulative effects of multiple traumas and intergenerational trauma.
Physical Changes in Adolescence
Overview: Physical transformations during adolescence provide the final preparation for adult roles, driven primarily by sexual maturity and critical brain development.
Sex, Gender, and the Adolescent
Hormonal Cascade: Puberty is triggered by a massive release of hormones, resulting in the maturation of reproductive organs and the emergence of secondary sex characteristics.
Males: Experience muscle growth, external genitalia maturation, facial hair, and larynx enlargement (deepening the voice).
Females: Experience menarche, breast development, external genitalia and uterine maturation, and shifts in body fat distribution.
Evolutionary Purpose: Prepares the individual for reproduction, accompanied by a sharp increase in sex drive.
Identity, Behaviour, and Orientation
Definitions:
Gender Identity: A person’s internal sense of being male or female.
Sex-Role Behaviour: Patterns of traditionally masculine or feminine behavior.
Sexual Orientation: A stable pattern of attraction to a certain sex (independent of identity or sex-role behavior).
Complex Variations: These variables combine in highly diverse ways:
Gay/Lesbian Individuals: Typically have a gender identity aligned with their biological sex, showing the same range of masculine/feminine sex-role behaviors as heterosexuals.
Androgen Insensitivity Syndrome (AIS): Genetic males (XY) who typically develop a female gender identity and female sex-role behaviors.
Congenital Adrenal Hyperplasia (CAH): Females exposed to high prenatal male hormones show elevated rates of bisexual/lesbian orientations, though the vast majority of women with CAH are heterosexual.
The Adolescent Brain
Contrary to older theories (like Piaget's) that assumed the brain was fully mature at puberty, contemporary psychologists view the early teen years as a second critical period of brain growth. While sensory and language areas are complete, major structural adjustments continue into young adulthood.
Structural Changes
Grey Matter: Substantial grey matter growth occurs at the onset of puberty, peaking between ages 11 and 12. It then thins out over the remaining teen years.
Clinical Link: Abnormalities in this thinning process are linked to schizophrenia. Youth with early-onset schizophrenia show 4x more grey matter loss in the frontal lobes than typical teens.
White Matter (Myelination): Myelin continues to insulate axons through the teen years and into young adulthood.
Frontal lobe myelination is significantly greater in adults (ages 23–30) than in adolescents (ages 12–16).
Adolescent white matter is highly vulnerable to environmental toxins, making it more susceptible to damage from activities like binge drinking.
Emotional Processing and Judgment
Misinterpreting Emotion: Adults accurately identify emotional expressions, whereas teens frequently misunderstand them.
Brain Activity: While both teens and adults show identical activity in the amygdala (quick, subconscious emotional assessment), adults show significantly higher activity in the frontal lobes, allowing for superior emotional judgment.
Risky Behaviour Dynamics: The earlier maturation of emotional structures (amygdala) relative to late-maturing logical structures (frontal lobes) explains heightened teenage risk-taking.
Risks are not taken due to an inability to understand danger; rather, teens experience a cognitive bias of personal immunity from negative consequences.
The adolescent brain responds much more intensely to pleasure than an adult brain, meaning immediate rewards easily overwhelm a teen's long-term judgment.
Adolescent Cognition
Executive Milestones: Working memory and reaction time both reach adult levels during adolescence.
Logical & Analytical Shift: Thinking transitions from concrete, experiential heuristics to logical and statistical reasoning.
Child heuristic: "My friend didn't get caught cheating, so I won't either."
Adolescent logic: "My friend got lucky, but the baseline probability of getting caught remains high."
Knowledge Base & Strategies: As teens accumulate data and build their knowledge bases, their use of executive strategies improves. A larger existing knowledge base makes learning new, subject-specific skills (e.g., solving statistics problems) significantly easier.
Moral Reasoning
Lawrence Kohlberg (a student of Piaget) extended cognitive theory to explain how moral reasoning develops. He presented participants with ethical dilemmas and analyzed the reasoning behind their choices, rather than the choices themselves.
Criticisms of Kohlberg's Theory
Cultural Bias: Postconventional reasoning heavily reflects Western, individualistic values centered on personal justice and individual rights.
Interpersonal Omission: The framework underrepresents collectivistic or non-Western cultures that prioritize interpersonal factors, such as duty, community responsibility, and care for others, over abstract individual rights.
Identity Formation in Adolescence
Erik Erikson’s Psychosocial Theory: Social development progresses through lifelong stages, each centered on a specific developmental tension or challenge.
The Adolescent Challenge (Identity vs. Role Confusion): The primary focus is answering the questions "Who am I?" and "What kind of person do I want to be?"
Successful Resolution: Achievement of identity—a unified, consistent sense of self.
Unsuccessful Resolution: Results in role confusion, which can complicate subsequent adult stages.
Short-Circuiting Identity: Because identity exploration can be uncomfortable, teens may prematurely adopt an identity by:
Group Affiliation: Merging into a clique, club, or gang to take on a preformed identity.
Foreclosure: Adopting ready-made identities handed down directly by parents or mentors without personal exploration.
Erik Erikson’s Full Psychosocial Stages Matrix
The Benefits of Ethnic Identity
Definition: How an individual feels about being a member of a specific ethnic or racial group.
Psychological Impact: A well-developed ethnic identity directly boosts overall self-esteem during adolescence and young adulthood.
Systemic Deprivation (The Canadian Context): The Canadian residential school system explicitly worked to strip Indigenous youth of their cultural identity via forced geographical isolation and assimilation. This historical cultural genocide caused severe, long-lasting psychological trauma that continues to impact subsequent generations (intergenerational trauma), as documented by the 2015 Truth and Reconciliation Report.
Family and Peer Influences
The Social Shift: Social activity naturally transitions away from the family unit and toward the peer group during adolescence.
The Power of Family Foundations: Despite peer alignment, maintaining strong family connections remains vital. Regular interactions (e.g., family dinners) serve as a major protective factor against drug use, alcohol abuse, tobacco use, and promiscuity.
Peer Dynamics and Vulnerability:
Social Exclusion: Adolescents show significantly heightened sensitivity and drop in mood following peer exclusion compared to adults over 22.
Risk-Taking: Teens are far more vulnerable to peer pressure; they make significantly more risky decisions when peers are present than when they are alone.
The "Stormy" Myth: Popular media characterizes adolescence as a period of extreme rebellion, but research shows most teens navigate it smoothly. The majority of adolescents love their parents, feel loved in return, share core values, and look to them for advice.
Development and the Law: The Youth Criminal Justice System
The Psychological Rationale: Unlike some developing systems that place youth with adults, Canada's federal Youth Criminal Justice Act (YCJA) treats youth separately because adolescents lack the fully formed psychological maturity of adults.
Focus of the YCJA: Prioritizes rehabilitation, specialized needs, and alternatives to custody over pure punishment or deterrence.
Outcomes: This approach has successfully lowered youth incarceration rates, avoiding the negative mental health outcomes linked to early imprisonment. However, Indigenous youth remain heavily overrepresented within this system.
Physical Status in Young Adulthood
Young adulthood is the peak of physical development.
Individuals are typically at their maximum strength, fitness, reaction time, and sensory ability.
The brain is fully mature during this stage.
Maintaining Health
In adulthood, lifestyle factors become more important than genetics in determining health outcomes.
Four healthy habits linked to longer life expectancy are:
eating fruits and vegetables
not smoking
drinking alcohol moderately or not at all
exercising regularly
Following these habits was associated with up to 14 additional years of life expectancy.
Cognition in Young Adulthood: Postformal Thought
Postformal thought is a more advanced form of thinking that develops in adulthood.
Unlike adolescents, adults recognize that many problems do not have one clear “right answer.”
Adult thinking is more flexible, realistic, and able to handle ambiguity and complexity.
Adolescents tend to think more absolutely and rely more on authority figures for answers.
Postformal thinking encourages independent and critical thinking.
It is important for creativity, problem solving, and generating new ideas in science and other fields.
Relationships in Young Adulthood
According to Erik Erikson, young adults face the challenge of intimacy vs. isolation.
Successful intimacy is easier when a strong identity has been developed during adolescence.
Failure to form close relationships can lead to loneliness and social isolation.
Family and Relationships
Modern families are diverse and may include marriage, cohabitation, single parenting, divorce, remarriage, or remaining single.
Public definitions of “family” have become broader and more accepting of different family structures.
Parenthood
Parenthood often becomes a major part of adult life.
Parents generally report higher happiness than nonparents, though this does not prove parenting causes happiness.
Having young children can temporarily reduce marital satisfaction because of increased stress and responsibilities.
Relationship quality can help buffer stress and reduce depression in parents, especially when raising children with special needs.
Social Media and Relationships
Social media often presents unrealistic “perfect relationship” images.
Comparing real relationships to idealized online portrayals can reduce relationship satisfaction.
Unhealthy behaviours, such as jealousy, control, and isolation, may sometimes be mistaken for love or romance.
Education about healthy and unhealthy relationships is important for young people.
What Happens During Midlife?
Midlife has no exact starting point, but it is often associated with physical changes, aging, and increased awareness of mortality.
Contrary to popular belief, most people do not experience a dramatic “midlife crisis.”
Midlife challenges may include balancing work, finances, children, aging parents, and relationship changes.
Physical and Cognitive Changes
The main pattern during midlife is stability, with gradual physical and cognitive changes.
Women and Menopause
Menopause is the end of menstruation and fertility, usually completed in the early 50s.
Symptoms during the transition may include hot flashes, night sweats, mood swings, headaches, and sleep problems.
Hormone treatments can reduce symptoms but may increase health risks such as stroke, heart attack, breast cancer, and dementia.
Men and Reproductive Changes
Men experience slower and more gradual reproductive changes.
Fertility declines with age but can remain possible into older adulthood.
Testosterone levels usually remain fairly stable during midlife.
Sexual Activity
For both men and women, having an available partner is a stronger predictor of sexual activity than health issues.
Social Changes in Midlife
Midlife is marked more by social and work changes than by major physical or cognitive changes.
Family Changes
Children often leave home, leading to the “empty nest” period.
Many parents experience improved marital satisfaction after children move out.
Emotional reactions to the empty nest vary across cultures.
In some cases, divorce rates may increase after children leave home.
Work and Career
Adults in midlife continue working and often become more experienced in their careers.
Some may change careers or face less stable employment conditions than previous generations.
Some workers may stay employed longer, while others take lower-skilled jobs or leave the workforce.
Erikson’s View of Midlife
According to Erik Erikson, midlife involves generativity vs. stagnation.
Generativity: feeling that one’s life has value and contributes to others, even if major goals are not fully achieved.
Stagnation: feeling dissatisfied and unproductive, with little sense of meaning or contribution.
Late Adulthood
The start of late adulthood is not clearly defined and varies across individuals and cultures.
Retirement age (around 65) is often used as a reference point, but many people work longer and view “old age” differently.
Life expectancy in Canada is approximately 80 years for males and 84 for females.
Physical Changes
Physical aging is generally gradual and mild in healthy individuals.
The brain slowly shrinks after midlife, but this does not usually cause major behavioural changes.
Sensory abilities may decline, but assistive devices (e.g., glasses, hearing aids) help compensate.
Cognitive Changes
Overall intelligence remains relatively stable with good health.
Only a small percentage of older adults develop dementia.
Dementia rates have decreased in recent decades, possibly due to better health and education.
Types of Intelligence
Crystallized intelligence (knowledge and experience) remains stable or improves with age.
Fluid intelligence (speed of processing and problem-solving) tends to decline with age.
Crystallized intelligence is often linked to “wisdom.”
Productivity and Aging
Creative and scientific productivity does not necessarily decline with age.
Research output is more influenced by motivation and opportunity than age.
Many major achievements, including Nobel Prizes, occur in later adulthood.
Social and Emotional Aspects of Late Adulthood
According to Erik Erikson, late adulthood involves integrity vs. despair.
Integrity: feeling satisfied with one’s life and accomplishments.
Despair: feeling regret that life did not turn out as hoped.
Well-Being in Older Adults
Contrary to stereotypes, older adults often report lower depression rates than younger adults.
Subjective well-being tends to be relatively high in later life.
A key reason is a shift in priorities: older adults focus more on emotional satisfaction and meaningful experiences.
Social Connections
Social connection remains important throughout life.
Older adults tend to have fewer friendships but place high value on them.
Relationships with siblings, adult children, and grandchildren are often especially meaningful.
The “grandmother effect” suggests older adults may have played an evolutionary role in supporting family survival.
Marriage and Relationships
Marriage in later life is linked to better health and happiness.
Long-term couples often become more similar over time and focus more on positive memories, which can improve satisfaction.
LGBTQ+ Aging
Older LGBTQ+ adults may face challenges such as discrimination and fear of stigma, especially in care settings.
Despite this, many report good mental health, supported by strong social networks and community connections.
Social support and inclusion are key factors in successful aging for this group.
Key Terms The Language of Psychological Science
Be sure that you can define these terms and use them correctly.
accommodation
adolescence
assimilation
attachment
circular reactions
concrete operational stage
conservation
conventional morality
egocentrism
embryo
equilibration
fetal alcohol spectrum disorder (FASD)
fetus
formal operational stage
identity
insecure attachment
menopause
object permanencepostconventional morality
preconventional morality
preoperational stage
pruning
puberty
secondary sex characteristics
secure attachment
sensorimotor stage
teratogen
theory of mind (TOM)
zone of proximal development
zygote