The psychology of design

Information

Users filter out a lot of the information that they receive, even when it could be important.
  • Hick’s Law. More options lead to harder decisions.
  • Confirmation Bias. People look for evidence that confirms what they think.
  • Priming. Previous stimuli influence users' decisions.
  • Cognitive Load. The total amount of mental effort that is required to complete a task.
  • Anchoring Bias. Users rely heavily on the first piece of information they see.
  • Nudge. Subtle hints can affect users' decisions.
  • Progressive Disclosure. Users are less overwhelmed if they're exposed to complex features later.
  • Fitt's Law. Large and close elements are easier to interact with.
  • Attentional Bias. Users' thoughts filter what they pay attention to.
  • Empathy Gap. People underestimate how much emotions influence user behaviors.
  • Visual Anchors. Elements used to guide users' eyes.
  • Von Restorff Effect. People remember more items that stand out.
  • Visual Hierarchy. The order in which people perceive what they see.
  • Selective Attention. People filter out things from their environment when in focus.
  • Survivorship Bias. People neglect things that don't make it past a selection process.
  • Sensory Adaptation. Users tune out the stuff they get repeatedly exposed to.
  • Juxtaposition. Elements that are close and similar are perceived as a single unit.
  • Signifiers. Elements that communicate what they will do.
  • Contrast. Users' attention is drawn to higher visual weights.
  • External Trigger. When the information on what to do next is within the prompt itself.
  • Decoy Effect. Create a new option that's easy to discard.
  • Center-stage Effect. People tend to choose the middle option in a set of items.
  • Framing. The way information is presented affects how users make decisions.
  • Law of Proximity. Elements close to each other are usually considered related.
  • Tesler's Law. If you simplify too much, you'll transfer some complexity to the users.
  • Spark Effect. Users are more likely to take action when the effort is small.
  • Feedback Loop. When users take action, feedback communicates what happened.
  • Expectations Bias. People tend to be influenced by their own expectations.
  • Aesthetic-Usability Effect. People perceive designs with great aesthetics as easier to use.

Meaning

When users try to give sense to information, they make stories and assumptions to fill the gaps.
  • Social Proof. Users adapt their behaviors based on what others do.
  • Scarcity. People value things more when they're in limited supply.
  • Curiosity Gap. Users have a desire to seek out the missing information.
  • Mental Model. Users have a preconceived opinion of how things work.
  • Familiarity Bias. People prefer familiar experiences.
  • Halo Effect. People judge things (or people) based on their feelings towards one trait.
  • Miller’s Law. Users can only keep 5±2 items in their working memory.
  • Unit Bias. One unit of something feels like the optimal amount.
  • Flow State. Being fully immersed and focused on a task.
  • Skeuomorphism. Users adapt more easily to things that look like real-world objects.
  • Reciprocity. People feel the need to reciprocate when they receive something.
  • Authority Bias. Users attribute more importance to the opinion of an authority figure.
  • Pseudo-Set Framing. Tasks that are part of a group are more tempting to complete.
  • Variable Reward. People enjoy rewards, especially unexpected ones.
  • Group Attractiveness Effect. Individual items seem more attractive when presented in a group.
  • Curse of Knowledge. Not realizing that people don't have the same level of knowledge.
  • Aha! moment. When new users first realize the value of your product.
  • Self-Initiated Triggers. Users are more likely to interact with prompts they set up for themselves.
  • Survey Bias. Users tend to skew survey answers towards what's socially acceptable.
  • Cognitive Dissonance. It's painful to hold to opposing ideas in our mind.
  • Goal Gradient Effect. Motivation increases as users get closer to their goal.
  • Feedforward. When users know what to expect before they take action.
  • Occam’s Razor. Simple solutions are often better than the more complex ones.
  • Noble Edge Effect. Users tend to prefer socially responsible companies.
  • Hindsight Bias. People overestimate their ability to predict outcomes after the fact.
  • Law of Similarity. Users perceive a relationship between elements that look similar.
  • Law of Prägnanz. Users interpret ambiguous images in a simpler and more complete form.
  • Spotlight Effect. People tend to believe they are being noticed more than they really are.
  • Fresh Start Effect. Users are more likely to take action if there's a feeling of new beginnings.

Time

Users are busy so they look for shortcuts and jump to conclusions quickly.
  • Labor Illusion. People value things more when they see the work behind them.
  • Default Bias. Users tend not to change an established behavior.
  • Investment Loops. When users invest themselves, they're more likely to come back.
  • Loss Aversion. People prefer to avoid losses more than earning equivalent gains.
  • Commitment & Consistency. Users tend to be consistent with their previous actions.
  • Sunk Cost Effect. Users are reluctant to pull out of something they're invested in.
  • Decision Fatigue. Making a lot of decisions lowers users' ability to make rational ones.
  • Reactance. Users are less likely to adopt a behavior when they feel threatened.
  • Observer-Expectancy Effect. When researchers' biases influence the participants of an experiment.
  • Weber's Law. Users adapt better to small incremental changes.
  • Law of the Instrument. If all you have is a hammer, everything looks like a nail.
  • Temptation Coupling. Hard tasks are less scary when coupled with something users desire.
  • Parkinson’s Law. The time required to complete a task will take as much time as allowed.
  • Dunning-Kruger Effect. People tend to overestimate their skills when they don't know much.
  • Affect Heuristic. People's current emotions cloud and influence their judgment.
  • Hyperbolic Discounting. People tend to prioritize immediate benefits over bigger future gains.
  • Cashless Effect. People spend more when they can't actually see the money.
  • Self-serving bias. People take credit for positive events and blame others if negative.
  • Pareto Principle. Roughly 80% of the effects come from 20% of the causes.
  • Discoverability. The ease with which users can discover your features.
  • Backfire Effect. When people's convictions are challenged, their beliefs get stronger.
  • False Consensus Effect. People overestimate how much other people agree with them.
  • Barnum-Forer Effect. Some people believe in astrology and fortune-telling.
  • IKEA Effect. When users partially create something, they value it way more.
  • Planning Fallacy. People tend to underestimate how much time a task will take.

Memory

Users try to remember what's most important, but their brain prefers some elements over others.
  • Provide Exit Points. Invite users to leave your app at the right moment.
  • Peak-End Rule. People judge an experience by its peak and how it ends.
  • Sensory Appeal. Users engage more with things appealing to multiple senses.
  • Zeigarnik Effect. People remember incomplete tasks better than completed ones.
  • Endowment Effect. Users value something more if they feel it's theirs.
  • Chunking. People remember grouped information better.
  • Picture Superiority Effect. People remember pictures better than words.
  • Method of Loci. People remember things more when they're associated with a location.
  • Shaping. Incrementally reinforcing actions to get closer to a target behavior.
  • Delighters. People remember more unexpected and playful pleasures.
  • Internal Trigger. When users are prompted to take action based on a memory.
  • Recognition Over Recall. It's easier to recognize things than recall them from memory.
  • Storytelling Effect. People remember stories better than facts alone.
  • Negativity Bias. Users recall negative events more than positive ones.
  • Availability Heuristic. Users favor recent and available information over past information.
  • Spacing Effect. People learn more effectively when study sessions are spaced out.
  • Serial Position Effect. It's easier for users to recall the first and last items of a list.