Unit 3.4: Cognitive Development Across the Lifespan

Key Ideas:

• Children are "little scientists" actively exploring and making sense of the world
• Development proceeds in universal, invariant stages (same order for everyone)
• Each stage involves qualitatively different thinking (not just more knowledge)
• Biological maturation and environmental interaction drive development
• Children cannot skip stages or be taught concepts beyond their current stage

Example:

A toddler develops a "dog" schema based on the family pet — four legs, furry, barks, friendly. This schema helps them categorize and understand dogs they encounter.

Characteristics:

• Knowledge obtained through sensory experiences and motor actions
• Reflexes gradually become voluntary, coordinated actions
• No language or symbolic thought initially
• Live in the "here and now" — focused on immediate sensory experience
• Goal-directed behavior emerges (reaching for objects)

⭐ Major Milestone: Object Permanence

Object permanence is the understanding that objects continue to exist even when they cannot be seen, heard, or touched.

Development Timeline:

• 0-8 months: No object permanence — "out of sight, out of mind"
• 8-12 months: Search for partially hidden objects
• 18-24 months: Fully developed — search for completely hidden objects

Classic Test: Peek-a-boo — young infants act surprised each time you reappear because they lack object permanence

✅ What They CAN Do:

• Symbolic/representational thought: Use words, images, and objects to represent other things
• Pretend play: Engage in make-believe with symbolic representations (banana as phone)
• Language development: Rapidly acquire vocabulary and grammar
• Theory of mind (beginning): Start understanding others have different thoughts and beliefs (develops around age 4-5)

❌ Limitations (What They CANNOT Do):

Major Cognitive Achievements:

• Conservation: Understand that quantity remains constant despite changes in appearance (mass, volume, number)
• Reversibility: Can mentally reverse actions (pouring water back would restore original amount)
• Classification: Can organize objects into hierarchical categories
• Seriation: Can arrange objects in sequential order (smallest to largest)
• Decentration: Can consider multiple aspects of a situation simultaneously
• Logical reasoning: About concrete situations and physical reality

❌ Limitations:

• Struggle with abstract concepts (love, justice, freedom)
• Difficulty with hypothetical situations ("What if gravity didn't exist?")
• Need concrete objects or situations to reason logically
• Limited ability to think about thinking (metacognition)

Key Abilities:

• Abstract thinking: Reason about concepts not physically present (justice, morality, love)
• Hypothetical-deductive reasoning: Generate and systematically test hypotheses
• Propositional thought: Reason logically about verbal statements regardless of truth
• Metacognition: Think about thinking; reflect on own thought processes
• Scientific reasoning: Design controlled experiments, isolate variables
• Future orientation: Consider multiple possible futures and plan accordingly

⚠️ Important Note:

NOT everyone reaches formal operational thinking. Many adults continue to think primarily in concrete operational terms, especially in unfamiliar domains. Development to this stage depends on education, cultural context, and experience with abstract reasoning tasks.

Stage	Age	Key Milestone	Main Limitation
Sensorimotor	0-2 years	Object permanence	No symbolic thought
Preoperational	2-7 years	Symbolic thought, language	No conservation, egocentrism
Concrete Operational	7-11 years	Conservation, logical thought	No abstract reasoning
Formal Operational	12+ years	Abstract, hypothetical thought	Not everyone reaches this stage

Key Differences from Piaget:

• Piaget: Children are "little scientists" discovering principles through individual exploration
• Vygotsky: Children are "little apprentices" learning from experts in their culture
• Piaget: Development drives learning (must be ready for new concepts)
• Vygotsky: Learning drives development (instruction can advance thinking)
• Piaget: Universal stages independent of culture
• Vygotsky: Development shaped by cultural tools and social context

Three Levels:

• Tasks I can do alone: Below the ZPD — already mastered, not challenging enough
• Tasks I can do with help (THE ZPD): Optimal learning zone — challenging but achievable with support
• Tasks I cannot do even with help: Above the ZPD — too difficult, causes frustration

Example:

A child can dress themselves with buttons (mastered) but cannot tie shoelaces independently. With a parent guiding each step, they can tie their shoes. Tying shoelaces is in their ZPD. Assembling complex machinery would be beyond their ZPD.

Scaffolding Techniques:

• Breaking complex tasks into smaller, manageable steps
• Modeling the desired behavior or skill
• Providing hints and prompts
• Asking guiding questions
• Offering encouragement and feedback
• Gradually removing support as competence increases (fading)

Example:

Teaching a child to bake: First, adult does everything while child watches. Next, child measures ingredients with guidance. Then child follows recipe with occasional help. Finally, child bakes independently. Support is gradually withdrawn as skills develop.

Function and Development:

• Helps children guide their own behavior and thinking
• Internalized social speech becomes inner thought
• Most common during challenging tasks within the ZPD
• Gradually becomes internalized as inner speech (talking in your head)
• Sign of cognitive self-regulation developing

Example: A child building blocks says aloud, "First I need the big one, then the medium one on top..."

Processing Speed

• Reaction times slow with age
• Takes longer to process information and make decisions
• Affects performance on timed tasks
• Can be compensated by experience and knowledge

Memory Changes

• Working memory: Declines (harder to hold and manipulate information)
• Episodic memory: Most affected (personal experiences, events)
• Semantic memory: Relatively preserved (general knowledge, facts)
• Procedural memory: Well-maintained (motor skills, habits)
• Encoding new information becomes more difficult
• Retrieval takes longer but can be aided with cues

✅ What Remains Strong or Improves:

• Vocabulary and language comprehension
• Expertise in familiar domains
• Wisdom and practical problem-solving
• Emotional regulation and well-being

Characteristics of Dementia:

• Severe memory impairment (especially recent events)
• Difficulty with language, communication, and recognition
• Impaired reasoning and judgment
• Disorientation to time and place
• Changes in personality and behavior
• Inability to perform daily activities independently

Alzheimer's Disease

Alzheimer's disease is the most common cause of dementia, accounting for 60-80% of cases.

Progression:

• Early stage: Recent memory loss, difficulty finding words, mild confusion
• Middle stage: Increasing memory loss, difficulty recognizing people, behavioral changes
• Late stage: Severe memory loss, loss of physical abilities, requires total care

Biological basis: Abnormal protein deposits (amyloid plaques and tau tangles) damage and kill brain cells, especially in hippocampus and cortex