Developmental Psychology: Piaget, Erikson, and Key Theories

Piaget's Cognitive Developmental Stages

Jean Piaget studied how children think and how their thinking changes over time. He proposed four stages: Sensorimotor, Preoperational, Concrete Operational, and Formal Operational.

Sensorimotor Stage

Birth-2 yrs. Infants learn through senses and actions; develop object permanence (understanding that objects exist even when unseen).

Preoperational Stage

2-7 yrs. Use of symbols and language develops; egocentric thinking (can't see others' viewpoints); animism (believing objects are alive).

Concrete Operational Stage

7-11 yrs. Logical thought about concrete events; understand conservation (quantity stays the same despite shape change).

Formal Operational Stage

12+ yrs. Abstract and hypothetical thinking; problem-solving, reasoning, and moral thinking develop.

Erikson's Psychosocial Stages

Erik Erikson proposed 8 stages of psychosocial development, each with a key conflict that shapes personality.

Infancy Stage

0-1. Trust vs. Mistrust. Positive outcome: Feeling safe and cared for. Negative outcome: Fear, insecurity.

Toddlerhood Stage

1-3. Autonomy vs. Shame/Doubt. Positive outcome: Independence ("I can do it"). Negative outcome: Doubt abilities.

Preschool Stage

3-6. Initiative vs. Guilt. Positive outcome: Initiative, confidence. Negative outcome: Feeling guilty about needs/desires.

School Age Stage

6-12. Industry vs. Inferiority. Positive outcome: Hard work, achievement. Negative outcome: Feeling inadequate.

Adolescence Stage

12-18. Identity vs. Role Confusion. Positive outcome: Strong sense of self. Negative outcome: Confusion about identity.

Young Adulthood Stage

18-40. Intimacy vs. Isolation. Positive outcome: Meaningful relationships. Negative outcome: Loneliness.

Middle Adulthood Stage

40-65. Generativity vs. Stagnation. Positive outcome: Contributing to society, parenting. Negative outcome: Self-absorption.

Late Adulthood Stage

65+. Integrity vs. Despair. Positive outcome: Acceptance of life. Negative outcome: Regret, despair.

Developmental Stages

Predictable periods of growth and change in physical, cognitive, and social development.

Nature vs. Nurture Controversy

Nature = Heredity and genetics; Nurture = Environment, upbringing, culture, and experience. Psychologists debate how much of human behavior is shaped by genes vs. environment.

Modern View of Nature vs. Nurture

Both interact — genes provide potential, environment shapes expression.

Example of Intelligence

Intelligence is influenced by both genetic factors (IQ inheritance) and environmental ones (schooling, nutrition).

The Case of the 'Jim Twins'

Identical twins separated at birth and reunited as adults.

Transduction

The process by which sensory receptors convert physical energy (light, sound, chemicals) into neural signals that the brain can interpret. Example: Light hitting the retina becomes electrical signals sent to the brain.

Absolute Threshold

The minimum stimulation needed to detect a stimulus 50% of the time. Example: The faintest sound you can hear in a quiet room.

Most Complex Sense for Humans

Vision is the most developed and complex sense. Humans rely heavily on visual input for understanding their environment. About 30% of the brain's cortex is involved in processing visual information.

Learning Definition

Learning is a relatively permanent change in behavior due to experience. Not caused by temporary states like fatigue or hunger.

Primary Reinforcer

Naturally satisfying, fulfills biological needs. Examples: Food, water, warmth, sleep.

Secondary Reinforcer

Learned value through association. Examples: Money, grades, praise.

Operant Conditioning

Learning through consequences (rewards/punishments). Example: Student studies to earn good grades.

Classical Conditioning

Learning through association between two stimuli. Example: Dog salivates to bell.

Rewards and Punishments

Rewards (Reinforcers) increase the likelihood of a behavior. Punishments decrease the likelihood of a behavior. Used in operant conditioning to shape behavior.

Positive Reinforcement

Add something pleasant to increase behavior (e.g., giving candy for good work).

Negative Reinforcement

Remove something unpleasant to increase behavior (e.g., stopping loud noise when task is done).

What Is Memory?

Any system that encodes, stores, and retrieves information. Memory allows us to retain knowledge and apply past experiences to the present.

The Three Memory Processes

Encoding - Getting information into the memory system. Storage - Keeping information over time. Retrieval - Accessing stored information when needed.

Types/Stages of Memory

1. Sensory Memory → 2. Working (Short-Term) Memory → 3. Long-Term Memory.

Sensory Memory

Duration: Less than 1 second, Capacity: Very large, Function: Holds sensory input briefly (visual & auditory).

Working/Short-Term Memory

Duration: ~20-30 seconds, Capacity: 7 ± 2 items, Function: Actively processes information.

Long-Term Memory

Duration: Potentially lifetime, Capacity: Unlimited, Function: Stores information permanently.