Overview
This lecture explores key psychological effects and cognitive biases that shape human perception, decision-making, memory, and behavior—often without conscious awareness.
Illusory Truth Effect
- Repeating information increases belief in its truth, even if it's false.
- Familiarity is a mental shortcut; repeated exposure tricks the brain into accepting statements as facts.
- Examples include common myths (e.g., "we use 10% of our brains").
- Used in propaganda, advertising, and political messaging.
Zeigarnik Effect
- Unfinished tasks or stories linger in our minds more than completed ones.
- Creates mental tension, boosting focus and motivation to finish.
- Marketers use it with cliffhangers, trials, and teasers.
- Writing unfinished tasks down can help relieve anxiety.
Reverse Psychology & Anchoring Bias
- Telling someone not to do something increases their desire to do it (reverse psychology).
- Anchoring bias: the first information heard sets a reference point for all future judgments.
- Used in sales, negotiations, and first impressions.
Ben Franklin Effect & Paradox of Choice
- People who do favors for you come to like you more (Ben Franklin effect).
- Too many options make decision-making harder, increasing regret and dissatisfaction (Paradox of Choice).
Door-in-the-Face & Foot-in-the-Door Techniques
- Door-in-the-face: start with a big request, then ask for a smaller one to improve compliance.
- Foot-in-the-door: start with a small request, then escalate to larger requests.
Decoy & Scarcity Effects
- Decoy effect: a less attractive third option steers choices toward a targeted option.
- Scarcity effect: perceived rarity or limited availability increases desirability.
Framing & Frequency/Baader-Meinhof Effects
- Framing: Presentation (positive vs negative) alters perception and decisions.
- Frequency illusion: After learning something new, we notice it everywhere.
Halo & Horn Effects
- Halo effect: One positive trait influences all judgments about a person.
- Horn effect: One negative trait leads to an overall negative perception.
Social Influence Effects
- Bystander effect: The more people present, the less likely anyone acts in an emergency.
- Social proof: People mimic others, especially in uncertain situations.
Cognitive Comfort Effects
- Mere exposure effect: Repeated exposure increases liking.
- Cognitive dissonance: Discomfort from conflicting beliefs/actions leads to rationalizations.
Expectation Effects
- Pygmalion effect: High expectations improve performance.
- Golem effect: Low expectations lead to poorer performance.
- Spotlight effect: People overestimate how much others notice them.
- Pratfall effect: Harmless mistakes by competent people increase likability.
Emotional & Memory Effects
- FOMO: Fear of missing out drives anxiety and impulsive behavior.
- Hedonic treadmill: Happiness levels reset after positive or negative events.
- Loss aversion: Fear of loss outweighs pleasure of gain.
- Endowment effect: Ownership increases perceived value.
Knowledge & Perception Biases
- Dunning-Kruger effect: Incompetent people overestimate abilities; experts underestimate theirs.
- False consensus: Assuming others share your beliefs.
- Just-world hypothesis: Belief that good/bad happens only to those who deserve it.
- Placebo/nocebo effects: Expectations produce real positive or negative outcomes.
Memory & Attention Biases
- Ostrich effect: Avoiding bad news to reduce stress.
- Hindsight bias: Belief that events were predictable after they happen.
- IKEA effect: More effort in creation increases attachment.
- Curse of knowledge: Experts struggle to explain to beginners.
- Serial position effect: Remembering beginnings and ends better than middles.
- Barnum effect: Accepting vague statements as highly personal.
- Self-fulfilling prophecy: Expectations shape reality.
Persuasion, Manipulation, and Decision Biases
- Contrast principle: Judgments depend on what is compared.
- Repetition persuasion: Frequent statements seem more true.
- Fear-then-relief: Relief after fear increases compliance.
- Sleeper effect: Weak arguments become persuasive over time.
- Priming effect: Subtle cues influence later behavior.
- Peak-end rule: Experiences are remembered by high points and endings.
- Status quo & default biases: Preference to maintain current or default states.
- Reciprocity principle: Obligation to return favors.
- False memory effect: Memories can be distorted or fabricated.
Key Terms & Definitions
- Illusory Truth Effect — Belief in information increases with repetition.
- Zeigarnik Effect — Unfinished tasks stick in memory.
- Reverse Psychology — Making people desire what’s forbidden.
- Anchoring Bias — First information sets the standard for judgment.
- Ben Franklin Effect — Doing favors makes people like you.
- Paradox of Choice — Too many options hinder decision-making.
- Decoy Effect — Irrelevant option steers choices.
- Scarcity Principle — Rarity increases perceived value.
- Framing Effect — Presentation changes perception.
- Halo/Horn Effects — Single traits bias overall judgment.
- Social Proof — Following group behaviors.
- Cognitive Dissonance — Mental distress from conflicting beliefs.
- Pygmalion/Golem Effects — High/low expectations shape performance.
- FOMO — Fear of missing out.
- Hedonic Treadmill — Return to baseline happiness.
- Loss Aversion — Losses hurt more than gains please.
- Endowment Effect — Overvaluing owned items.
- Dunning-Kruger Effect — Ignorance breeds confidence.
- Placebo/Nocebo Effects — Expectation causes real health effects.
- Ostrich Effect — Ignoring unpleasant information.
- Hindsight Bias — "Knew it all along" illusion.
- IKEA Effect — Effort increases attachment.
- Curse of Knowledge — Experts fail to explain to novices.
- Serial Position Effect — First and last remembered best.
- Barnum Effect — Vague personal statements seem accurate.
- Self-Fulfilling Prophecy — Beliefs bring themselves true.
- Contrast Principle — Context alters value judgments.
- Repetition Persuasion — Repeats seem more true.
- Default/Status Quo Bias — Preference for existing conditions.
- Reciprocity Principle — Obligation to return favors.
- False Memory Effect — Forming memories of things that didn’t happen.
Action Items / Next Steps
- Review and memorize key terms and their real-life examples.
- Reflect on which biases have influenced your own recent decisions.
- Apply critical thinking when you notice repetition, strong emotions, or social pressure.
- Complete any assigned readings or case studies related to cognitive bias.