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Prenatal Development

• Week 1: A zygote differentiates into three germ layers: ectoderm, mesoderm, and endoderm.
  • The ectoderm develops into nerve tissue and skin.
  • The mesoderm develops into muscle and bone.
  • The endoderm is the source of soft tissue, such as organs and the digestive tract.
• Week 4: The central nervous system differentiates into the forebrain, midbrain, hindbrain, and spinal cord.
• Week 6: Sex chromosomes begin their expression.
• Week 7: Cerebral cortex cells begin to develop.
• Weeks 9-12: Internal reproductive organs begin to form.
• Weeks 21-24: Myelination of the nervous system occurs.
• Weeks 25-28: The majority of the brain cells form.

Teratogens

• A teratogen is any factor that can cause a birth defect.
• Fetal Alcohol Spectrum Disorder (FASD) refers to conditions that occur in an individual if the mother consumes alcohol during pregnancy.
• Fetal Alcohol Syndrome (FAS) is included within FASD.
  • FAS is characterized by physical abnormalities such as: growth retardation, skin folds at the corner of the eyes, nose and mouth abnormalities, and small head circumference.
  • FAS also includes cognitive and behavioral problems like reduced IQ, attention problems, and poor impulse control.

Newborn Reflexes (Birth to 28 Days)

• Grasping: Newborns will grasp any object placed in their palm.
• Rooting: Newborns turn their heads towards stimuli touching the side of their face.
• Sucking: Newborns will suck on objects placed in their mouth.
• Swallowing: Newborns swallow.
• Tonic Neck Reflex: Newborns turn their heads in the direction their arms are facing.
• Stepping Reflex: Occurs when parents hold newborns upright with their feet touching a surface.

Nervous System Development

• The grey matter experiences rapid growth from the later months of pregnancy to 18 months old.
• Myelin growth occurs around gestational month 6.
• A spurt in myelin growth occurs between 6-13 years old.
  • The end of this growth coincides with the end of a sensitive period for language development.

Motor Development

• Motor development follows a head-to-toe direction.
• By 2 months old, infants can control the muscles of their neck and shoulders.
• Around 3 months old, the muscles in the torso begin to develop.
• From 6-9 months old, infants begin crawling and some skipping motions.
• Around 1 year old, the leg muscles develop enough to support weight.

Jean Piaget's Theory of Cognitive Development

• Equilibration: The process in which a child engages in assimilation and accommodation to make sense of the world.
• Sensorimotor Stage: From birth to 2 years old, infants focus on the present and rely on sensations that evoke motor responses.
  • Primary Circular Reactions (1-4 months old): Involve the infant’s own body.
• Secondary Circular Reactions (4-8 months old): Involve objects other than their own body.
• Tertiary Circular Reactions (12 months old): Involve trial-and-error experimentation.
• Object permanence is achieved at 8 months old.
• Language Development:
  • At 18 months, children have a vocabulary of 10-50 words.
  • By 2 years, children begin combining words into short, meaningful sentences.
• Preoperational Stage: From 2 to 6 years old, children are incapable of engaging in internal mental operations or manipulations.
  • They develop the concept of conservation and egocentrism.
  • Their reasoning is limited by beliefs that appearances are real.
• Concrete Operational Stage: From 6-11 years old, children can easily solve problems of conservation.
  • Thinking becomes more logical but they cannot handle abstract concepts.
  • Reason best when allowed to engage in hand-on learning.
• Formal Operational Stage: Around 12 years old, adolescents develop the ability to handle abstract concepts and improve in problem-solving.
  • Younger children solve problems by trial-and-error, while adolescents strategically think through several alternatives.
  • Abstract thinking stimulates a burst of idealism.

Alternative Approaches to Cognitive Development

• Lee Vygotsky introduced the concept of the zone of proximal development, which refers to tasks that a child can accomplish with assistance.
• Believed that what children can do with assistance is more telling than what they can do individually.
• Scaffolding: Being responsive to the child's needs and providing guidance.

Theory of Mind (ToM)

• Theory of Mind is understanding that others have thoughts that are different from our own.
• It emerges between 3 to 4 years old.

Temperament

• Surgency (or extraversion) indicates the degree to which a child is generally happy, active, vocal, and social.
• Negative Effect: Proneness to anger, fear, sadness, and frustration, as well as the degree to which a child is shy and not easily soothed.
• Effortful Control: The ability to pay attention and inhibit behavior.

Attachment

• Mobility is a factor in predicting the timing of attachment.
• Infants typically learn to crawl around the same time (between 6 to 8 months).
• This phase is important to social development.
• Anxious-Avoidant Attachment: Children did not react to the mother leaving or returning.
• Anxious-Resistant Attachment: Children were never comfortable, even when the mother was around, and were distressed when the mother left.
• Disorganized Attachment: Children seemed confused and not well-attached with contradictory behavior.

Adolescent Brain

• The brain is not fully adult.
• This is a second critical period of brain growth.
• Adolescents may misunderstand emotions due to the early maturation of emotional parts of the brain relative to the logical frontal lobes.
• Accounts for risky behaviour, more vigorous response to pleasure.

Cognitive and Moral Development

• Lawrence Kohlberg developed stages of moral reasoning: Preconventional morality, conventional morality, and post-conventional morality.

Social and Emotional Development in Adolescents

• Erik Erikson is known for his life span model of psychosocial development.
• Challenges for adolescents: Identity development.
• Challenges for adults: Intimacy vs. isolation.
• Challenges for late adults: Integrity or Despair.

Physical Changes in Late Adulthood

• Changes are gradual and mild.
• Speed of learning and problem-solving experiences mild changes.
• Sensory changes are gradual.

Cognition in Late Adulthood

• Intelligence remains relatively stable.
• Fluid intelligence shows a change.

Miscellaneous Human Development Information

• Human development involves the examination of continuity and change across the lifespan.
• Sensation and perception, cognition and language, social and moral behavior, and emotion.
• Four main periods of human development: prenatal and infancy (conception to age 2-3), childhood (ages 3-11), adolescence (age 11 to brain maturation), and adulthood (brain maturation to death).

Early Experience in Infancy

• Early experiences are crucial for normal development and can give rise to individual differences.
• In Utero: Infants cannot hear clear speech, but only muffled sounds and rhythms. Respond to the mother being touched and doing. Taste and smell aren’t differentiable (in the brain as well).
• Prenatal Development: Consists of conception (when the egg is fertilized until it implants in the uterine wall), the embryonic stage (when vital organs begin to develop), and the fetal period.
• During the Fetal Period: There is much experience-dependent learning, neurogenesis, myelination, and synaptic pruning.
• In Utero: Fetal heartbeat changes in reaction to external voices.
• There is unique reaction to music (different rhythm from speech). Newborn babies can recognize their mother's language and voice.

Infant Perception

• Preferential Looking: Infants choose to spend more time looking at interesting, stimulating, or familiar objects and events.
• Grating Visual Acuity Test: Relies on the principle that infants prefer to look at stripes rather than a plain grey surface, as they are more visually interesting.
  • Tests visual acuity.
  • At 1 month old, visual acuity increases from 20/400 to 20/120.
  • By 6 months old, infants develop adult-like acuity, including color and depth perception.

Motor Development in Infancy

• Follows the cephalocaudal rule ("top-to-bottom") and the proximodistal rule ("inside-to-outside").
• Has a clear effect on visual development (crawling vs walking).

Identity in Childhood

• Children describe themselves in physical terms and almost always positively.
• Positivity bias declines quickly at school.

Erikson's Identity Theory for Adolescents

• Identity Confusion: Common in 13 to 14-year-olds.
• Results in an incomplete and incoherent sense of self.
• Identity Foreclosure: Includes university students and premature identities of choice. Negative Identity: Teenagers doing the opposite of what their parents say.
• The result of Identity is formed in opposition to others/social norms.
  • Involves the emergence of abstract thinking and personality traits becoming more important.

Other Challenges in Adolescents

• Emergence of Self-Socialization: Choosing one's own social partners, friends and social groups become of paramount importance.
• Personal Fable: Belief that their experiences are so unique that no one understands what they're going through.
• Imaginary Audience: The idea that everyone is watching, noticing one's flaws.
• Adults still experience this, but they know how to manage it better.

Adulthood

• Changes occur in the sensory system and brain structure.
• There are changes in memory storage and retrieval, along with a slowing of cognitive processes.
• Adults employ better cognitive strategies because of their vast experience, which helps make up for their cognitive decline.