Cognitive development is how thinking, memory, problem-solving, and reasoning change from infancy through adulthood. In AP terms you should know Piaget’s stages (sensorimotor—object permanence, preoperational—egocentrism/conservation failures, concrete operational—logical concrete thinking, formal operational—abstract/hypothetical thought) and concepts like schemas, assimilation, and accommodation. Also know Vygotsky’s ideas: social learning, scaffolding, and the zone of proximal development. Across adulthood, crystallized intelligence (facts/skills) stays steady while fluid intelligence (processing speed, novel problem solving) tends to decline; some adults experience disorders like dementia. Learning this helps you explain behavior and answer both multiple-choice and FRQ items in Unit 3 (Development and Learning)—Topic 3.4 is tested on things like applying theories to behavior (3.4.A). For a focused review, see the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR), the unit overview (https://library.fiveable.me/ap-psych-new/unit-3), and practice problems (https://library.fiveable.me/practice/ap-psych-new).

Think of Piaget like a map of how kids learn to think—four stages that build on each other. - Sensorimotor (0–2 yrs): Babies learn by sensing and doing. They form schemas (mental frameworks) and develop object permanence—knowing things still exist when out of sight. - Preoperational (2–7 yrs): Toddlers use symbols and pretend play but can’t do conservation or reversibility. They show egocentrism (can’t take another’s view) and often animate objects. Theory of mind starts to emerge. - Concrete operational (7–11 yrs): Kids fix the preoperational errors—they understand conservation, logic about concrete things, and can do reversible thinking, but struggle with abstract or hypothetical ideas. - Formal operational (12+ yrs): Teens/adults can think abstractly and hypothetically. Piaget said not everyone reaches this stage. Remember assimilation (fitting new info into old schemas) and accommodation (changing schemas for new info). These stages are tested on the AP exam under Topic 3.4—you’ll be asked to explain behaviors using these terms. For a quick review, see the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) and try practice problems (https://library.fiveable.me/practice/ap-psych-new).

Assimilation and accommodation are how kids change their schemas (mental frameworks) in Piaget’s theory. Assimilation means fitting new info into an existing schema—e.g., a child who knows “dog” calls a cat a dog because it fits their animal schema. Accommodation means changing the schema when new info doesn’t fit—e.g., the child learns “cat” is different and updates their categories. Together they drive cognitive development across Piaget’s stages: kids continuously assimilate and occasionally accommodate, producing more complex thinking (sensorimotor → formal operational). This distinction is a direct CED keyword you should know for Topic 3.4 (3.4.A.1). For quick review, see the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) and practice questions (https://library.fiveable.me/practice/ap-psych-new) to prep for multiple-choice and FRQ connections.

Think of Piaget as moving from concrete to abstract—four clear stages you can chunk and cue by age + key ability: - Sensorimotor (0–2): schemas form by sensing/moving; object permanence develops. - Preoperational (2–7): mental symbols, pretend play, egocentrism, animism; CAN’T do conservation or reversibility; beginning theory of mind. - Concrete operational (7–11): logical about concrete info; fixes preop errors (conservation, reversibility) but struggles with abstract/hypothetical. - Formal operational (11+): abstract, hypothetical, systematic thinking—not everyone reaches this. Remember tips: link one keyword to each stage (object permanence → sensorimotor; conservation → concrete) and practice with MCQs and FRQs (AP often asks you to identify stage from behaviors). Review the CED keywords above and use the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) plus 1,000+ practice Qs (https://library.fiveable.me/practice/ap-psych-new) to drill examples you’ll see on the exam.

Object permanence is the understanding that objects continue to exist even when you can’t see, hear, or touch them. Piaget says it develops during the sensorimotor stage (infancy to toddlerhood) as babies build schemas through assimilation and accommodation. Early on, infants who haven’t developed object permanence will act as if a hidden toy no longer exists; once they grasp it, they’ll search for the toy under a blanket—showing they're forming stable mental representations. Why it matters: object permanence is a foundation for memory, goal-directed behavior, and later skills like attachment and problem solving (it signals that babies can hold information mentally). For AP Psych, this links directly to 3.4.A.1.i (sensorimotor stage) and the idea of schemas. For more review, see the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) and try practice questions (https://library.fiveable.me/practice/ap-psych-new).

The preoperational stage (toddlerhood → early childhood) is when kids get good at using mental symbols—words, images, pretend play—and start developing a theory of mind (they begin to understand others have thoughts). But they still can’t do several key tasks Piaget used to identify the stage: they struggle with conservation (quantity stays same despite appearance changes), reversibility (mentally reversing steps), and logical, systematic reasoning. Typical errors you’ll see: egocentrism (assuming others see/think exactly like them), animism (attributing life to inanimate objects), and centration (focusing on one obvious feature and ignoring others). For the AP exam, you should be able to name these abilities and limitations and connect them to later stages (concrete operational corrects many preoperational errors). Review this CED-aligned summary on Fiveable (study guide) and practice questions to solidify examples (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR; practice problems: https://library.fiveable.me/practice/ap-psych-new).

Egocentrism and animism are both common in Piaget’s preoperational stage (toddlerhood–early childhood), but they’re different errors in thinking. Egocentrism = kids can’t yet take another person’s perspective: they assume everyone sees, thinks, and feels exactly like they do (classic: child covers own eyes and thinks you can’t see them). Animism = kids give lifelike qualities to inanimate objects, believing things like toys or the sun have feelings or intentions (classic: “the stuffed bear is sad”). Both reflect limited theory of mind and symbolic thinking in this stage and are things kids usually outgrow by concrete operations when they can understand others’ viewpoints and reason more logically. For AP exam study, link these directly to Piaget’s preoperational stage, and know examples for multiple-choice or FRQs (see the Topic 3.4 study guide: https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR). For more practice questions, check https://library.fiveable.me/practice/ap-psych-new.

They can’t do conservation because of how thinking works in Piaget’s preoperational stage (toddlerhood through early childhood). Kids at this stage use symbols and pretend play, but their thinking is dominated by centration (focusing on one obvious feature, like height of liquid), egocentrism (difficulty taking another perspective), and a lack of reversibility (can’t mentally reverse steps). So when you pour water from a short wide cup into a tall skinny cup, they focus on the taller appearance and say there’s more—even though volume hasn’t changed. Conservation and reversibility emerge in the concrete operational stage when children can logically transform and compare quantities. This is exactly the kind of content AP Psych tests under Topic 3.4 (use terms like centration, egocentrism, reversibility). For a quick review, see the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) and try practice Qs (https://library.fiveable.me/practice/ap-psych-new).

Theory of mind is the ability to understand that other people have their own thoughts, beliefs, and perspectives that can differ from your own. In AP terms it’s linked to social-cognitive development (Piaget’s preoperational stage): kids begin to form mental representations of others’ minds but are still often egocentric. Practically, children typically start showing basic theory-of-mind skills between about 3–5 years old and reliably pass classic false-belief tasks (like understanding that someone can hold a belief that’s false) around age 4. That shift helps explain why preschoolers move from egocentrism to more successful perspective-taking and social problem-solving. For AP study, this fits under Topic 3.4 (preoperational → developing theory of mind). For review and practice questions, see the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) and more practice at (https://library.fiveable.me/practice/ap-psych-new).

Piaget and Vygotsky both study cognitive development but they differ on mechanism and emphasis. Piaget describes stage-based, mostly universal changes: kids build schemas and change them through assimilation and accommodation across four discontinuous stages (sensorimotor → preoperational → concrete operational → formal operational). Development drives learning. Vygotsky sees children as social learners: cognitive growth happens continuously through interaction, language, and guided support (scaffolding). Key idea: learning occurs in the zone of proximal development (ZPD)—tasks a child can do with help but not alone. So Piaget emphasizes individual maturation and stage-based cognitive limits (egocentrism, conservation), while Vygotsky emphasizes sociocultural context, collaboration, and that instruction can advance development. Both appear in Topic 3.4; study the CED keywords (schemas, ZPD, scaffolding) and use the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) and Unit 3 overview (https://library.fiveable.me/ap-psych-new) for AP-style practice (https://library.fiveable.me/practice/ap-psych-new).

Zone of proximal development (ZPD)—a Vygotsky concept in the CED—is the range of tasks a learner can’t do alone but can complete with help from a more knowledgeable other. It’s where optimal learning happens because social interaction bridges current ability and potential development. Scaffolding is the temporary support that teacher, peer, or parent gives within the ZPD: modeling a task, giving hints, asking leading questions, breaking tasks into steps, and gradually removing help (fading) as the learner gains independence. Good scaffolding matches the learner’s current skills, promotes assimilation/accommodation of new schemas, and shifts responsibility to the student. On the AP exam, you may see ZPD/scaffolding tested in multiple-choice or applied free-response (see Q18 in the sample set). For more review, check the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR), unit overview (https://library.fiveable.me/ap-psych-new/unit-3), and practice problems (https://library.fiveable.me/practice/ap-psych-new).

Crystallized intelligence = facts, vocabulary, general knowledge you build up over time (think: knowing word meanings, historical dates, how to balance a budget). It stays relatively stable—often improves into adulthood—because it’s based on learned info and experience. Fluid intelligence = processing speed, working memory, novel problem-solving (think: solving a new logic puzzle or quickly spotting patterns). According to the CED, fluid tends to wane with age while crystallized remains stable. On the AP exam you might see this as a multiple-choice item (identify examples) or an FRQ link to lifespan changes in cognition (Topic 3.4). Want quick review or practice? Check the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) and thousands of practice questions (https://library.fiveable.me/practice/ap-psych-new).

Fluid intelligence drops with age because it depends on processing speed, working memory, and novel problem-solving—abilities tied to brain efficiency and neural processing that tend to slow or show age-related decline. Older adults often have slower reaction times, reduced working memory capacity, and changes in frontal lobe functioning, so tasks requiring quick reasoning or adapting to new situations get harder. Crystallized intelligence stays stable (or even improves) because it’s built from accumulated knowledge, vocabulary, and life experience—skills stored in long-term memory that don’t rely as much on rapid processing. So you might be slower at solving a new logic puzzle (fluid), but still great at trivia or using learned strategies (crystallized). This distinction is in the CED for Topic 3.4 (crystallized stable, fluid wanes). For review, see the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR) and practice questions (https://library.fiveable.me/practice/ap-psych-new). On the exam, expect items that test these definitions and how they apply to lifespan cognitive change.

Dementia is an umbrella term for chronic, progressive cognitive decline that interferes with daily life (memory, language, attention, executive functioning). In AP terms, it’s a cognitive disorder that typically appears in older adults and can reduce fluid intelligence (problem-solving, processing speed) while often leaving crystallized intelligence (general knowledge, vocabulary) relatively more intact early on. Common causes include Alzheimer’s disease, which first harms episodic memory and later executive skills and language. Dementia can make forming new memories, switching tasks, planning, and even recognizing people hard, and it impairs independence in activities of daily living. You should know dementia as an example of adult cognitive disorder for multiple-choice and FRQ contexts in Unit 3 (Topic 3.4). For a quick review tied to the CED keywords (crystallized vs. fluid intelligence, executive functioning), see the Topic 3.4 study guide on Fiveable (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR).

Short answer: Piaget said no—not everyone reaches the formal operational stage. Longer: According to Piaget, the formal operational stage (late childhood through adulthood) brings abstract and hypothetical thinking, but he explicitly proposed that some people never develop this level of reasoning (CED 3.4.A.1.iv). Whether someone reaches it depends on experience, schooling, culture, and the kinds of problems they practice solving—many adults think logically in concrete, realistic ways (concrete operational thinking) and struggle with systematic hypotheticals. On the AP exam you should be able to explain what formal operations look like (abstract/hypothetical thought) and note Piaget’s caveat that it’s not universal. For a quick review, see the Topic 3.4 study guide (https://library.fiveable.me/ap-psych-new/unit-3/4-cognitive-development-across-the-lifespan/study-guide/nn5a70iS0lJuR8RR). Practice applying this idea to sample items at (https://library.fiveable.me/practice/ap-psych-new).