Unit 2

Cognition: the one-page sheet

2.1 Perception

Perception turns sensations into meaning. It is built bottom-up from features and top-down from knowledge and expectations, filtered by limited attention, organized by Gestalt principles, given depth by binocular and monocular cues, and kept stable by perceptual constancy.

Bottom-up processing builds a percept from raw features; top-down processing uses knowledge, schemas and expectations (perceptual set). Both run at once.
Selective attention filters input. Important words still break through (the cocktail party effect), but unattended things can be missed (change blindness, inattentional blindness).
Gestalt principles group parts into wholes: proximity, similarity, closure and figure-ground.
Depth comes from binocular cues (retinal disparity, convergence) and monocular cues (relative size, interposition, linear perspective, texture gradient, relative clarity).
Perceptual constancy keeps size, shape and color stable; apparent movement turns still frames into motion.

bottom-up processing begins to build a picture of the scene top-down processing and perceptual set tilt what we perceive we see whole objects, at a distance, in three dimensions what we do not attend to can go unseen (inattentional and change blindness)

cognition: All the mental activity of knowing: perceiving, paying attention, thinking, remembering and using language.
perception: The process of organizing and interpreting sensory information so it has meaning. Sensation detects a stimulus; perception makes sense of it.
attention: Focusing mental resources on some information while ignoring the rest. It is limited, so what is not attended to may go unnoticed.
selective attention: Focusing awareness on one stimulus or task while filtering out others, such as following one conversation in a noisy room.
cocktail party effect: Noticing an important stimulus, such as your own name, among sounds you were ignoring. It shows that unattended input is still processed a little.
change blindness: Failing to notice a change in a scene, such as a swapped object between two shots of a film.
inattentional blindness: Failing to see an object in plain view because attention is on something else, as when people counting passes miss a person in a gorilla suit.
bottom-up processing: Perception that starts with the raw sensory features (lines, colors, edges) and builds them into a whole.
top-down processing: Perception guided by knowledge, expectations and experience, such as reading a messy word from the sentence around it.
schema: A mental framework that organizes knowledge about something (a restaurant, a dog, a first day of school) and shapes what we expect and notice.
perceptual set: A readiness to perceive something in a certain way, set up by expectations, context, recent experience or emotion.
Gestalt psychology: The idea that the brain organizes sensations into meaningful wholes; the whole is different from the sum of its parts. The Gestalt principles describe how parts are grouped.
closure (Gestalt): The Gestalt tendency to fill in gaps so that an incomplete outline is seen as a whole object.
figure-ground: The organization of a scene into an object (the figure) that stands out from its surroundings (the ground).
proximity (Gestalt): The Gestalt tendency to group things that are close together.
similarity (Gestalt): The Gestalt tendency to group things that look alike in color, shape or size.
depth perception: The ability to see the world in three dimensions and judge distance, from binocular and monocular cues.
binocular cue: A depth cue that needs both eyes: retinal disparity and convergence.
retinal disparity: A binocular cue: the two eyes see slightly different images of a scene, and the bigger the difference, the closer the object.
convergence: A binocular cue: the eyes turn inward to look at a near object, and the brain reads the amount of turning as distance.
monocular cue: A depth cue that works with one eye, such as relative size, interposition, linear perspective, texture gradient and relative clarity.
relative clarity: A monocular cue: hazy, blurry objects are seen as farther away than sharp, clear ones.
relative size: A monocular cue: of two objects thought to be the same size, the one with the smaller image is seen as farther away.
texture gradient: A monocular cue: surface detail looks coarse and spread out up close and finer and denser in the distance.
linear perspective: A monocular cue: parallel lines, like railroad tracks, seem to meet in the distance.
interposition: A monocular cue: an object that blocks part of another is seen as closer.
perceptual constancy: Perceiving objects as unchanging in size, shape and color even as the image on the retina or the lighting changes.
apparent movement: Perceiving motion in a rapid series of still images, as in a movie or a row of blinking lights (the phi phenomenon).

2.2 Thinking, Problem-Solving, Judgments, and Decision-Making

Thinking runs on concepts and prototypes, and schemas grow by assimilation and accommodation. Algorithms are slow and sure; heuristics are fast and usually right but produce predictable errors. Mental set and functional fixedness block solutions, framing and priming tilt choices, and executive functions and divergent thinking support good problem-solving.

A concept is a mental category; its prototype is the most typical example. New information is assimilated into a schema, or the schema is changed (accommodation).
An algorithm guarantees a solution step by step; a heuristic is a fast shortcut that can mislead.
The representativeness heuristic matches to a prototype; the availability heuristic goes by what comes to mind easily.
Problem-solving is blocked by mental set and functional fixedness; judgments are tilted by priming, framing, the gambler's fallacy and the sunk-cost fallacy.
Executive functions (prefrontal cortex) plan and control; creativity needs divergent thinking to generate ideas and convergent thinking to pick one.

we recognize and categorize quickly we assimilate it, or accommodate by changing the schema we use heuristics instead of algorithms predictable errors: availability, representativeness, framing, the gambler's and sunk-cost fallacies

concept (cognition): A mental category that groups similar objects, events, ideas or people, such as "bird" or "fruit".
prototype: The best or most typical example of a concept, used to judge whether new things belong. A robin is a prototype bird.
assimilation (cognition): Interpreting new information so it fits an existing schema, as when a child calls a cow a "dog".
accommodation (cognition): Changing a schema, or creating a new one, when new information does not fit, as when the child learns that cows are not dogs.
algorithm: A step-by-step procedure that guarantees a solution if followed, often slowly, such as trying every possible code.
heuristic: A mental shortcut that allows fast judgments and solutions. Heuristics usually work but can lead to errors.
representativeness heuristic: Judging how likely something is by how well it matches a prototype, often ignoring how common it is.
availability heuristic: Judging how likely or common something is by how easily examples come to mind. Vivid, recent events seem more common than they are.
mental set: The tendency to approach a problem in a way that worked before, even when another approach would work better.
functional fixedness: The tendency to see an object only in its usual function, which blocks seeing new uses for it.
priming: The activation, often without awareness, of related ideas by an earlier exposure, so that later related items come to mind faster.
framing effect: The way a choice is worded (for example as a gain or a loss) changing the decision, even when the facts are the same.
gambler's fallacy: The belief that past random outcomes change the chances of the next one, such as thinking black is "due" after a run of reds.
sunk-cost fallacy: Continuing a choice because of what has already been invested (money, time, effort) that cannot be recovered.
executive functions: Mental skills for planning, focusing, switching between tasks and controlling impulses. They depend heavily on the prefrontal cortex.
creativity: The ability to produce ideas that are both new and useful.
divergent thinking: Thinking that produces many different possible answers or ideas, such as listing uses for a brick.
convergent thinking: Thinking that narrows the possibilities to one best answer, as on a test with a single right answer.

2.3 Introduction to Memory

Memory is encoding, storage and retrieval. Explicit memory (episodic and semantic) can be stated; implicit memory (procedural) shows in what we do; prospective memory is remembering to act. Information moves from sensory to short-term to long-term memory, working memory is the active workspace, deeper processing gives stronger memories, and long-term potentiation strengthens the synapses involved.

Memory works in three steps: encoding, storage and retrieval.
Explicit memory can be stated: episodic (events) and semantic (facts). Implicit memory shows in behavior, like procedural skills. Prospective memory is remembering to act later.
The multi-store model: sensory memory, then short-term memory, then long-term memory. Working memory is the active short-term workspace: central executive, phonological loop, visuospatial sketchpad.
Some information is encoded by automatic processing, some only by effortful processing. Deep processing of meaning beats shallow processing.
Long-term potentiation strengthens synapses and is thought to underlie learning and memory.

sensory memory holds it for a moment it enters short-term (working) memory, where it can be worked on it is stored in long-term memory, supported by stronger synapses (LTP) retrieval brings it back into working memory

memory: The ability to keep information over time and use it later, through encoding, storage and retrieval.
encoding: Getting information into memory by turning it into a form the brain can store.
storage (memory): Keeping encoded information over time.
retrieval: Getting stored information back out of memory when it is needed.
explicit memory: Memory of facts and experiences that you can consciously recall and state (declarative memory). It includes episodic and semantic memory.
episodic memory: Explicit memory of personal events tied to a time and place, such as your last birthday.
semantic memory: Explicit memory of general facts and knowledge, separate from when you learned them, such as the capital of France.
implicit memory: Memory that shows in behavior without conscious recall (nondeclarative memory), such as skills and habits.
procedural memory: Implicit memory for skills and procedures, such as riding a bike or typing.
prospective memory: Remembering to do something in the future, such as taking medicine at noon.
long-term potentiation: Long-term potentiation: a lasting increase in the strength of a synapse after repeated stimulation, thought to be a neural basis of learning and memory.
multi-store model: The Atkinson-Shiffrin model: information passes from sensory memory to short-term memory to long-term memory.
sensory memory: A very brief record of sensory input: under a second for sights (iconic memory) and a few seconds for sounds (echoic memory).
short-term memory: A limited store that holds a few items for about 20 to 30 seconds unless they are rehearsed.
long-term memory: The relatively permanent, very large store of knowledge, skills and experiences.
working memory: The active part of short-term memory, where information is held and worked on. The model has a central executive (directs attention), a phonological loop (sounds and words) and a visuospatial sketchpad (images and places).
automatic processing: Encoding that happens without effort or intention, such as information about time, place and how often things happen.
effortful processing: Encoding that takes attention and effort, such as studying vocabulary.
levels of processing: The idea that how deeply information is processed affects memory: shallow processing (appearance, sound) gives weaker memory than deep processing (meaning).

2.4 Encoding Memories

Encoding improves when information is organized (mnemonics, the method of loci, chunking, hierarchies) and when study is spread out (distributed practice and the spacing effect) instead of crammed (massed practice). In a list, the first items (primacy) and last items (recency) are remembered best, giving the U-shaped serial position curve.

Mnemonics link new information to an easy pattern; the method of loci places items along an imagined route.
Chunking groups items into meaningful units; hierarchies organize from general to specific. Both use what you already know.
Distributed practice beats massed practice (cramming) for long-term memory: the spacing effect.
The serial position effect: the first items (primacy, in long-term memory) and last items (recency, still in short-term memory) are recalled best.

more of it fits in short-term memory and it links to what you know each session rebuilds the memory, so it lasts longer (the spacing effect) the first items reach long-term memory (primacy) and the last stay in short-term memory (recency) the recency effect fades but the primacy effect stays

mnemonic: A memory aid that links new information to a pattern, image or phrase that is easier to remember, such as an acronym like ROY G BIV.
method of loci: A mnemonic that places each item to be remembered at a location along a familiar route, then mentally walks the route to recall them (a memory palace).
chunking: Grouping separate pieces of information into larger, meaningful units, so short-term memory can hold more (a phone number as three chunks).
hierarchies (memory): Organizing information from broad categories down to specific details, such as an outline, which makes it easier to encode and retrieve.
spacing effect: The finding that study spread out over time leads to better long-term retention than the same amount of study done all at once.
distributed practice: Studying in several sessions spread out over time (spaced practice).
massed practice: Studying in one long session (cramming). It can help on a test soon after, but memories fade faster than with distributed practice.
serial position effect: The tendency to recall the first and last items in a list better than the middle ones, which gives a U-shaped serial position curve.
primacy effect: Better recall of the first items in a list, because they get more repetition and are encoded into long-term memory.
recency effect: Better recall of the last items in a list, because they are still held in short-term memory when recall begins.

2.5 Storing Memories

Repeating information (maintenance rehearsal) holds it briefly; linking it to meaning (elaborative rehearsal) stores it. New memories are consolidated over time with help from the hippocampus and sleep. Retrograde amnesia loses the past, anterograde amnesia blocks new memories, Alzheimer's disease gradually destroys memory, infantile amnesia is normal, and superior autobiographical memory is a rare extreme.

Maintenance rehearsal (repeating) keeps information in short-term memory; elaborative rehearsal (linking to meaning) moves it into long-term memory.
Memory consolidation stabilizes new memories over hours to days, helped by the hippocampus and sleep.
Retrograde amnesia loses memories from before an injury; anterograde amnesia blocks new memories after it, yet skills can still be learned.
Alzheimer's disease is a progressive disease that often begins with trouble forming new memories. Infantile amnesia is the normal lack of memories before about age 3.
Highly superior autobiographical memory is a very rare, extremely detailed memory for one's own life.

it stays in short-term memory for now but is often not stored it is encoded deeply into long-term memory it becomes stable retrograde or anterograde amnesia

maintenance rehearsal: Repeating information over and over to keep it in short-term memory. It holds information for now but does little to store it long term.
elaborative rehearsal: Linking new information to its meaning and to things you already know, which encodes it more deeply into long-term memory.
memory consolidation: The process by which a new memory is stabilized over hours to days, with help from the hippocampus and from sleep, so it lasts in long-term memory.
highly superior autobiographical memory: Highly superior autobiographical memory: a very rare ability to recall the events of one's own life, day by day, in great detail and without memory tricks.
amnesia: Memory loss, usually caused by brain injury, illness or disease.
retrograde amnesia: Loss of memories formed before a brain injury or illness. The most recent memories, not yet consolidated, are often lost first.
anterograde amnesia: An inability to form new long-term memories after a brain injury or illness, often from damage to the hippocampus. Old memories and new skills may be spared.
Alzheimer's disease: Alzheimer's disease: a progressive brain disease, most common in older adults, that damages neurons (often the hippocampus first) and gradually destroys memory and other thinking.
infantile amnesia: The normal inability of adults to recall events from the first few years of life, roughly before age 3 or 4.

2.6 Retrieving Memories

Retrieval depends on cues. Recognition is usually easier than recall because the options are cues. Matching the place, body state or mood of learning helps retrieval. Practicing retrieval (the testing effect) strengthens memory more than rereading, and good metacognition means checking what you know by testing yourself instead of trusting familiarity.

Recall produces information with few cues; recognition picks it from options, which act as retrieval cues, so it is usually easier.
Retrieval is easier when cues match learning: the place (context-dependent), the body's state (state-dependent), and the mood (mood-congruent).
Retrieval practice (self-quizzing) beats rereading for long-term memory: the testing effect.
Metacognition is judging your own learning. Familiarity from rereading feels like knowing but is not; testing yourself is the honest check.

those features become retrieval cues retrieval is easier (context-dependent, state-dependent and mood-congruent memory) retrieval routes get stronger (the testing effect) students overestimate what they know, a failure of metacognition

recall (memory): Retrieving information with few cues, as on a fill-in-the-blank or essay question.
recognition (memory): Identifying information you have seen before among options, as on a multiple-choice question. It is usually easier than recall.
retrieval cue: Any stimulus, such as a word, smell, place or photo, that helps bring a stored memory back.
context-dependent memory: Better recall when the external setting at retrieval matches the setting where the memory was formed.
state-dependent memory: Better recall when your internal state (calm, sleepy, after caffeine or a drug) at retrieval matches your state when you learned.
mood-congruent memory: The tendency to recall memories that match your current mood, such as sad memories when you feel sad.
retrieval practice: Studying by pulling information out of memory, such as self-quizzing or writing what you remember, instead of rereading it.
testing effect: The finding that retrieving information, as on a practice test, strengthens long-term memory more than spending the same time restudying it.
metacognition: Thinking about your own thinking, including judging how well you know something and choosing how to study.

2.7 Forgetting and Other Memory Challenges

We forget quickly at first and then more slowly (the forgetting curve). Forgetting comes from encoding failure, interference (proactive and retroactive) and retrieval failure; repression is the psychodynamic account, with weak evidence. Because memory is reconstructed, misleading information, forgotten sources and imagination can produce confident false memories.

The forgetting curve: much is lost quickly, then the rest fades slowly. Spacing and retrieval practice flatten it.
Forgetting can be encoding failure (never stored), interference (proactive: old blocks new; retroactive: new blocks old), or retrieval failure (the tip-of-the-tongue state).
Repression is the psychodynamic account of forgetting threatening memories; the evidence for it is weak.
Memory is constructive: the misinformation effect, source amnesia and imagination inflation can create confident false memories.

it is never stored (encoding failure) retrieval is blocked (proactive or retroactive interference) gaps are filled with expectations (constructive memory) confident false memories form (misinformation effect, imagination inflation)

forgetting curve: The pattern, first measured by Ebbinghaus (1885), in which much newly learned information is forgotten quickly and the rest fades more slowly.
encoding failure: Forgetting because information never got into long-term memory, often because it was never attended to.
interference (memory): Forgetting because other learning gets in the way of retrieving a memory.
proactive interference: Older learning disrupting the recall of newer learning, such as entering last year's locker code.
retroactive interference: Newer learning disrupting the recall of older learning, such as new French words crowding out old Spanish ones.
tip-of-the-tongue phenomenon: The tip-of-the-tongue phenomenon: feeling sure you know something, and recalling parts of it such as the first letter, without being able to retrieve it yet.
repression: The psychodynamic idea that anxiety-provoking memories are pushed out of awareness. It is widely questioned, because traumatic events are usually remembered well.
misinformation effect: The misinformation effect: misleading information received after an event changes a person's memory of it.
source amnesia: Remembering information but forgetting, or mistaking, where it came from (source misattribution).
constructive memory: The idea that memories are rebuilt each time they are retrieved, using stored pieces plus schemas and expectations, so they can change.
imagination inflation: Increased confidence that an event really happened after imagining it repeatedly.
false memory: A memory of an event or detail that did not happen, or did not happen that way, often held with confidence.

2.8 Intelligence and Achievement

Intelligence tests measure a general ability (g) that shows up across many tasks, though some theories stress separate abilities. Modern scores are standardized on a normal curve (mean 100, SD 15) and must be reliable and valid. Scores are shaped by context (stereotype threat and lift, the Flynn effect), group gaps are not explained by within-group heritability, tests have a history of misuse, and beliefs about ability (growth and fixed mindsets) affect effort.

General intelligence (g) explains why different tests correlate; multiple-ability views stress separate strengths.
The original IQ was $\frac{\text{mental age}}{\text{chronological age}} \times 100$ . Modern tests are standardized: a normal curve, mean 100, SD 15.
A good test is reliable (test-retest, split-half: consistent) and valid (construct, predictive: measures what it should).
Scores are shaped by context: stereotype threat and lift, the Flynn effect, and the fact that within-group differences do not explain between-group gaps. Tests have been misused against immigrants and minority groups.
Achievement tests measure what you learned; aptitude tests predict what you can learn. A growth mindset sees ability as developable; a fixed mindset does not.

many researchers propose a general intelligence, g scores can be placed on a normal curve and read as percentiles its scores are consistent and predict what they should scores are misread, as in the history of testing immigrants and the misuse of group differences

intelligence: The ability to learn from experience, solve problems and use knowledge to adapt to new situations.
general intelligence: General intelligence (g): a broad mental ability, proposed by Spearman, that underlies performance on many different kinds of tests, which is why their scores correlate.
multiple intelligences: The view that intelligence is several distinct abilities rather than one general ability. Popular theories of this kind (such as Gardner's) have limited evidence that the abilities are truly separate.
mental age: The level of performance typical of children of a given age, used on early intelligence tests. A child who does as well as typical 10-year-olds has a mental age of 10.
intelligence quotient: Intelligence quotient. Originally mental age divided by chronological age, times 100. Modern tests compare a score with others of the same age on a normal curve with a mean of 100 and a standard deviation of 15.
standardization: Giving a test in the same way to everyone and setting norms from a large, representative sample, so individual scores can be compared with them.
reliability: The consistency of a test's scores: the same person scores about the same on two occasions (test-retest reliability) or on the two halves of the test (split-half reliability).
validity: How well a test measures or predicts what it is meant to. Construct validity: it measures the intended trait. Predictive validity: its scores predict a later outcome, such as grades.
stereotype threat: A drop in performance when people fear confirming a negative stereotype about their group. Early studies found large effects; later, larger studies suggest the effect is smaller and less consistent.
stereotype lift: A small rise in performance when people are reminded of a negative stereotype about a different group they are compared with.
Flynn effect: The Flynn effect: the rise in average intelligence test scores across generations during the 20th century, too fast to be genetic. It has stalled or reversed in some countries.
within-group variation: Within-group variation is the spread of scores inside one group; between-group variation is the difference between groups' averages. A trait can be strongly heritable within groups while a gap between groups is caused by the environment.
achievement test: A test of what a person has already learned, such as a final exam.
aptitude test: A test designed to predict a person's future performance or capacity to learn.
growth mindset: The belief that abilities can be developed through effort, good strategies and help from others.
fixed mindset: The belief that abilities are fixed and cannot be changed much by effort.