Cognition
High-Yield Summary
- Cognition is how the brain processes and reacts to information; humans' large frontal lobe supports especially complex thought. Dual-coding theory (Paivio): verbal + visual encoding together build redundancy that aids retrieval.
- Piaget: cognitive development proceeds through schemata, modified by assimilation (fitting new info into an existing schema) and accommodation (changing the schema to fit new info).
- Piaget's four stages, in order: sensorimotor (circular reactions → object permanence) → preoperational (symbolic thinking, egocentrism, centration) → concrete operational (conservation, others' perspectives) → formal operational (abstract, logical reasoning).
- Vygotsky's sociocultural theory: cognitive development is driven by a child internalizing their culture's rules, symbols, and language — contrasts with Piaget's focus on independent construction of knowledge.
- Late adulthood: reaction time slows, prospective memory declines, IQ drops between ages 30-40. Fluid intelligence (raw problem-solving) peaks early; crystallized intelligence (accumulated knowledge) peaks later — education/stimulation are protective for both.
- Dementia = gradual, generally irreversible decline (most often Alzheimer's, or vascular dementia from reduced blood flow). Delirium = acute, fluctuating, generally reversible, from an identifiable medical cause.
- Cognition can be disrupted by genetic conditions (Down syndrome, Fragile X), prenatal exposures (fetal alcohol syndrome), birth complications, brain infection, and trauma (shaken baby syndrome).
Key Terms
- Schema
- A concept, behavior, or sequence of events that organizes a piece of knowledge.
- Object permanence
- Understanding that objects continue to exist even when out of view; marks the end of the sensorimotor stage.
- Egocentrism
- Inability to imagine what another person might think or feel (preoperational stage).
- Centration
- Focusing on only one aspect of a situation at a time, underlying difficulty with conservation.
- Conservation
- Understanding that a quantity stays the same even when its appearance changes (mastered by concrete operational stage).
- Fluid intelligence
- Raw, novel problem-solving ability; peaks in early adulthood.
- Crystallized intelligence
- Accumulated use of learned skills and knowledge; peaks in middle adulthood.
Assimilation vs. Accommodation
| Assimilation | Accommodation |
|---|---|
| Classifies new information into an existing schema | Modifies an existing schema to encompass new information that doesn't fit |
Piaget's Four Stages, in Order
- 1Sensorimotor (birth-2 yrs): learning through primary/secondary circular reactions; ends with object permanence, the start of representational thought.
- 2Preoperational (2-7 yrs): symbolic thinking (pretend/make-believe); limited by egocentrism and centration, which cause difficulty with conservation.
- 3Concrete operational (7-11 yrs): understands conservation and others' perspectives; logical thought as long as it's grounded in concrete objects.
- 4Formal operational (~11+ yrs): logical, abstract reasoning — e.g. systematically controlling variables one at a time (Piaget's pendulum experiment).
Dementia vs. Delirium
| Dementia | Delirium |
|---|---|
| Gradual, generally irreversible decline | Rapid fluctuation, typically reversible |
| Starts with impaired memory, progresses to impaired judgment/confusion, personality change | Caused by an identifiable medical factor: electrolyte/pH disturbance, malnutrition, low blood sugar, infection, drug reaction, alcohol withdrawal, pain |
| Most common cause: Alzheimer's disease; vascular dementia from reduced blood flow (small clots, high blood pressure) | Resolves once the underlying medical cause is treated |
Common MCAT Trap
- Assimilation fits new information into an existing schema; accommodation changes the schema itself.
- Know both the order and the defining feature of each of Piaget's four stages — a passage will test which stage a described behavior belongs to.
- Fluid intelligence (novel problem solving) peaks early and declines earlier; crystallized intelligence (accumulated knowledge) peaks later and declines more slowly.
- Dementia is gradual and generally irreversible; delirium is acute, fluctuating, and generally reversible once treated — don't mix them up in a vignette.
Quick Recall
A toddler calls every four-legged animal a 'doggy.' Which process is this — assimilation or accommodation?
A child understands that pouring water from a short, wide glass into a tall, thin one doesn't change its amount. Which stage, and which ability?
Whose theory emphasizes a child's internalization of culture, rules, symbols, and language as the driver of cognitive development?
An elderly patient shows a sudden, fluctuating change in cognition tied to a urinary tract infection. Dementia or delirium?
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