Psychology

You don't calculate what you see — your perceptual system picks up affordances (possibilities for action) directly from the light, sound, and texture around you. No mental processing required.

Seeing is like solving a puzzle. Your brain uses past experience to fill in gaps — which is why optical illusions fool us: our brain's "hypothesis" about what it's seeing turns out to be wrong.

Marr described perception like an algorithm: first detect edges, then figure out depth, then build a full 3D model. It was a revolutionary attempt to describe vision as information processing.

You see what you expect to see. If you expect a face in the crowd, you'll find one faster. Perception is a continuous loop between your internal model of the world and what you actually look at.

The brain is like a single telephone line. Only one call gets through at once. Broadbent thought we filter out distractions before we even process their meaning — that's why you can't follow two conversations simultaneously.

The filter doesn't fully block unattended input — it just turns it down. Your name in a noisy room still grabs your attention because it has a permanently low threshold. Treisman refined Broadbent's model to explain the "cocktail party effect."

Think of attention as mental fuel. Easy tasks burn little fuel; hard tasks burn more. You can multitask as long as the combined fuel demand doesn't exceed your tank — that's why texting while driving is dangerous.

If you're reading a dense legal document (high load), you won't notice the TV in the background. If you're reading a children's book (low load), every distraction competes for your attention. How hard a task is determines how distractable you are.

Information enters through your senses, briefly held in STM (about 7 items for ~20 seconds), and if rehearsed, transfers to LTM where it can last forever. Forgetting happens when information is lost between stores.

You remember what you think about deeply. Rote repetition (shallow) fades fast. Connecting new information to what it means, why it matters, and how it links to your life (deep) makes it stick.

Your working memory is more like a workbench with multiple tools than a single bucket. The phonological loop handles words and numbers (inner voice), the sketchpad handles images and space (inner eye), and the central executive decides where attention goes.

You can hold about 7 items in mind at once — which is why phone numbers are 7 digits. But a "chunk" can be expanded: instead of remembering 9 individual letters, you remember 3 three-letter words. Chunking dramatically expands effective memory capacity.

Where were you on 9/11? Most people remember exactly. Emotionally shocking events seem to trigger a special "record" mechanism in the brain — though research shows these memories are vivid but not necessarily accurate.

Rats press levers for food pellets; children study for gold stars. Skinner showed that behavior is almost entirely controlled by consequences. Positive reinforcement (reward) is far more effective than punishment for shaping lasting behavior.

A child who only knows dogs might call every four-legged animal "dog" (assimilation), then learn to distinguish cats (accommodation). Piaget showed that children aren't just mini-adults — they think in qualitatively different ways at each stage.

You can't quite do it alone, but you can do it with a little help. The gap between what you can do alone and what you can do with guidance is the ZPD. Vygotsky argued that social interaction and language are the engines of cognitive development.

System 1 is your gut: fast, automatic, always on. System 2 is your inner analyst: slow, effortful, reserved for hard problems. Most of the time you run on autopilot (System 1) — which is efficient but error-prone.

Losing £50 hurts more than gaining £50 feels good. We're not rational calculators — we're more sensitive to losses than gains, and we overweight small probabilities and underweight large ones. This explains why people buy lottery tickets and avoid necessary medical tests.

When stakes are low or time is short, people use simple rules of thumb. When a decision really matters, they switch to more careful analysis. No single strategy fits all situations — good decision-making is about choosing the right strategy for the context.

Some people just seem to be generally smart at everything — that's what g captures. Spearman noticed that people who score well on one mental test tend to score well on others. He proposed a single underlying "general intelligence" driving performance across domains.

The student who struggles with algebra but creates breathtaking paintings isn't "less intelligent" — they have a different kind of intelligence. Gardner challenged the idea that IQ tests capture the full range of human ability.

Street smarts, book smarts, and creative smarts are all different. The student who aces exams but can't navigate a city without GPS has high analytical but low practical intelligence. Sternberg argued all three matter for success in life.

Fluid intelligence is your raw reasoning power — figuring out a puzzle you've never seen. Crystallized intelligence is everything you've learned — vocabulary, facts, expertise. Gf peaks in young adulthood; Gc keeps growing throughout life.

You don't see a bear, feel fear, and then run. You see the bear, run, and then feel fear as you notice your racing heart. Emotions follow bodily changes, not the other way around.

When you see the bear, your body goes into alarm AND you feel afraid at the same time — not one then the other. Cannon thought the body's response is too slow and non-specific to be the cause of distinct emotions.

Your racing heart after coffee or after seeing your ex feel the same physiologically. The emotion you label it as depends on context. This explains misattribution of arousal — why frightening situations can intensify romantic feelings.

Two people lose their jobs. One feels devastated; the other feels liberated. The event is the same, but the appraisal differs. Lazarus put cognition first: what you think about something determines how you feel about it.

You can't focus on writing poetry when you're starving. Lower needs (food, safety, belonging) must be met before higher ones (esteem, self-actualization) motivate behavior. Most people never reach the top — not because they fail but because life keeps pushing them back to lower levels.

Paying people fairly prevents them from being unhappy — but it doesn't make them love their job. True motivation comes from the work itself: challenge, recognition, growth. Herzberg's insight: removing dissatisfaction ≠ creating motivation.

You'll work hard if you believe (a) effort will lead to success, (b) success will lead to a reward, and (c) the reward is worth having. Motivation collapses if any link in the chain is weak.

"Do your best" is weaker than "score 85% on this exam." Specific, hard goals focus attention, mobilize effort, and drive persistence. The key: the goal must be accepted as legitimate and feedback must show progress.

These five dimensions capture the fundamental ways people differ. High Conscientiousness predicts career success; high Neuroticism predicts mental health vulnerabilities. The Big Five emerged from factor analysis of thousands of personality descriptors, not from theory — the data revealed the structure.

Introverts have a chronically higher arousal level — that's why they need quiet to function and seek stimulation less than extraverts. Eysenck grounded personality in neuroscience, arguing these dimensions reflect real differences in brain physiology.

You are not entirely aware of why you do what you do. The unconscious — your hidden desires, fears, and unresolved conflicts — drives much of your behavior. Freud was controversial but permanently changed how we think about the hidden forces behind human action.

People don't just "decide" to change and do it. They cycle through stages — often moving backward before forward. A smoker might be in precontemplation for years before even considering quitting. Meeting someone at their current stage is key to effective behavior change support.

You can't just tell people to change — you first have to shake their confidence in the old way (unfreeze), guide them through the transition, then lock in the new behavior through reward and culture (refreeze). Most organizational changes fail at unfreezing.

The more you hear a song, the more you like it — even if it's not objectively good. Familiarity breeds liking. This is why advertisers repeat ads obsessively and politicians put their faces everywhere. You don't need to evaluate something consciously to be influenced by it.

If you smoke and believe smoking kills you, something has to give. You either quit smoking (change behavior), convince yourself it won't happen to you (change belief), or find reasons why it's actually fine (rationalization). Dissonance is the discomfort; the mind rushes to resolve it.

When a doctor explains your diagnosis in detail and you reason through it, you're persuaded centrally — durably. When a celebrity endorses a product and you buy it because they're attractive, you're persuaded peripherally — shallowly. The route taken depends on motivation and ability to process.

When who you are closely matches who you wish you were (ideal self) and how others see you (social self), you feel secure and authentic. Large gaps between these selves produce anxiety. Therapy, in Rogers' view, means helping people accept themselves as they actually are.

You feel pride when your country wins the World Cup even if you didn't kick a ball. Your team is part of your identity. Social Identity Theory explains why people discriminate even in trivial group settings — because their group's status reflects on their own self-esteem.

You check your salary against your colleagues', not against billionaires. Social comparison drives much of everyday anxiety and ambition. Upward comparison (to people doing better) can inspire or depress; downward comparison (to people doing worse) can reassure or make you complacent.

In Asch's experiment, people denied the evidence of their own eyes to agree with a group that gave clearly wrong answers. Conformity is so powerful that we'll doubt our own senses rather than stand out. Most conformity happens not from stupidity but from the social cost of being different.

65% of participants administered what they believed were dangerous electric shocks to an innocent person — simply because an experimenter in a white coat told them to. Milgram showed that atrocities don't require evil people; they require hierarchical authority and diffused responsibility.

We return favors (reciprocity), stick to what we've said (consistency), follow what others do (social proof), defer to experts (authority), say yes to people we like (liking), and want what's scarce. Cialdini catalogued the shortcuts that make us predictably persuadable — and exploitable.

Majorities create conformity pressure; minorities create genuine attitude change. A persistent minority who never wavers makes the majority doubt themselves. This is how social movements work — consistent repetition of a position forces the majority to actually engage with it.

Every team starts polite (forming), then argues about direction (storming), settles into roles (norming), does its best work (performing), and eventually disbands (adjourning). Knowing which stage your team is in helps you manage it — the storming phase is normal, not a sign of failure.

Every team needs someone with ideas (Plant), someone who finishes things (Completer), someone who manages relationships (Teamworker). Problems arise when roles are missing or duplicated. Knowing your natural role helps you contribute more effectively and fill gaps more strategically.

The same person behaves differently in different groups. Groups have their own "personality" — shaped by norms, history, and power dynamics. Lewin founded group dynamics as a field and showed that changing groups requires changing the forces within the group, not just the individuals.

If you like Alice and Alice likes Bob, you'll feel pressure to like Bob too (balanced). If you like Alice but Alice hates Bob — and you like Bob — that's uncomfortable (imbalanced). You'll either change your attitude toward Bob, Alice, or rationalize the inconsistency.

Relationships are like business transactions. We assess whether rewards outweigh costs and whether this relationship beats what else is available. This sounds cynical, but it accurately predicts relationship satisfaction and stability — people leave when the balance tips.

We Google "evidence that vaccines are harmful" rather than "what does the science say about vaccines." Once we believe something, we selectively notice evidence that confirms it and ignore evidence that doesn't. It's the most pervasive and consequential cognitive bias.

A coat originally priced £500 reduced to £200 feels like a bargain — even if £200 is still overpriced. The first number you hear (the anchor) distorts all subsequent judgments. Salary negotiators, car dealers, and trial lawyers all exploit anchoring.

After seeing news coverage of plane crashes, people fear flying more than driving — even though driving is far more dangerous. Vivid, memorable events feel more probable than they are. We judge frequency by ease of recall, not by actual data.

The less you know about a subject, the less you know how much you don't know. Novices have no framework to assess their ignorance. Experts know enough to know how complex the field is. This is why the most confident voice in the room is often not the most informed one.

Staying in a bad job because you've already spent 10 years there. Finishing a meal you don't like because you paid for it. The money is gone either way — past investment should be irrelevant to future decisions. But our brains refuse to write off "wasted" effort.

"95% survival rate" feels reassuring; "5% death rate" feels alarming — for the same surgery. The content is identical; the framing is everything. Doctors, politicians, and marketers use framing constantly to nudge decisions without changing any facts.

We give our own group the benefit of the doubt. Identical résumés rated higher when the name sounds like "our kind." Sports fans see fouls by the opposing team, not by their own. In-group bias is automatic, universal, and operates even in meaninglessly random groups.

After the 2008 financial crisis, everyone "knew" it was coming. But they didn't — they just revised their memory of how predictable it seemed. Hindsight bias makes us overconfident in our ability to predict the future and prevents genuine learning from past failures.