Unit 15: Development Across the Lifespan
What a newborn already knows, how a child's model of other minds comes online, and what changes and what holds steady as the brain ages.
5 topics · 15 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
What Newborns Can Already Perceive
- How it worksHow do researchers use how long a baby looks at something to figure out what a baby who can't talk can already perceive?
- Worked exampleFind how the preferential-looking method tells whether a baby can tell two similar shades of color apart.
- Common mistakeWhy isn't a newborn's blank stare proof that its visual system starts out doing nothing at all?
Your turn1 of 2
A newborn only minutes old cannot talk, point, or follow instructions, yet researchers still confidently report that it prefers looking at a face over a scrambled version of the same features. A student wonders how researchers could possibly know what a baby who cannot communicate can actually perceive. How do researchers use how long a baby looks at something to figure this out?Piaget's Stages of Cognitive Development
- How it worksHow do Piaget's four stages track a child's growing ability to reason about objects, categories, and abstract logic?
- Worked exampleFind why a 3 year old insists a tall thin glass has more juice than a short wide glass holding the identical amount, a failure of conservation.
- Common mistakeWhy isn't a young child's mistake on a conservation task just a matter of not paying close enough attention?
Your turn1 of 2
A baby acts as though a toy has vanished from existence the instant it disappears behind a blanket, while an older child understands the toy is still there, just hidden from view. A student assumes these two children must simply differ in how much they already know about toys specifically. How do Piaget's four stages track this kind of broader cognitive change?The Development of Theory of Mind
- How it worksHow does the Sally-Anne false-belief task reveal the moment a child grasps that other people can hold beliefs that are wrong?
- Worked exampleFind why most children pass the false-belief task around age 4 but fail it reliably at age 3.
- Common mistakeWhy isn't a 3 year old's failure on the false-belief task just about weak memory rather than a missing concept?
Your turn1 of 2
In false-belief task studies, about 29 percent of 3-year-olds pass, while about 81 percent of 4-year-olds pass. Find how many more percentage points pass at age 4 than at age 3.The Adolescent Brain and Risk-Taking
- How it worksHow does a fully developed emotional and reward system paired with a still-maturing prefrontal cortex produce a gap between impulse and control?
- Going furtherWhat happens to a teenager's risk-taking in a driving simulator when friends are watching versus when they are alone?
- Common mistakeWhy isn't teenage risk-taking simply a matter of not knowing the risks are dangerous?
Your turn1 of 2
A teenager takes a risky shortcut while driving with friends in the car that they would never attempt while driving completely alone. A parent assumes teenagers must simply be worse at assessing danger than adults across the board, regardless of who else is present. How does a fully developed emotional and reward system paired with a still-maturing prefrontal cortex produce this gap between impulse and control specifically around peers?Cognitive Change in Aging
- How it worksHow does fluid intelligence, the speed of raw processing, decline with age while crystallized intelligence, accumulated knowledge, holds steady or grows?
- Common mistakeWhy isn't cognitive aging a uniform decline across every single mental ability at once?
- Going furtherWhat happens to the gap between fluid and crystallized intelligence as a person moves from their 30s into their 70s?
Your turn1 of 2
A 70 year old struggles to quickly recall a new phone number just given to them, yet still solves a crossword puzzle faster than a 20 year old sitting nearby. A student assumes cognitive ability must simply decline uniformly with age, so this pattern seems contradictory. How does fluid intelligence declining with age while crystallized intelligence holds steady or grows explain this pattern?