Every time users interact with your product, they:
🙈 Filter the information
🔮 Seek the meaning of it
⏰ Act within a given time
💾 Store bits of the interaction in their memories
So to improve your user experience, you need to understand the biases & heuristics affecting those four decision-cycle steps.
TL,DR
According to the growth.design team, 101 cognitive bias and principles that affect UX. Below is the list of the ones that struck us the most.
fmfmerian Over to you, feel free to explore the full list and add your favorite ones too!
Hick's Law
Hick's Law
Hick's Law predicts that the time and the effort it takes to make a decision, increases with the number of options. The more choices, the more time users take to make their decisions.
Confirmation Bias
Confirmation Bias
People tend to search for, interpret, prefer, and recall information in a way that reinforces their personal beliefs or hypotheses.
Add a caption...
Contrast
The user's attention is drawn to higher visual weights.
Color is an inherent part of design. Designers have been known to agonize over choosing a hue or hexcode in the hopes of conveying a specific mood or message in a design. It's important to test colors matching & contrast.
Centre-Stage Effect
People tend to choose the middle option in a set of items.
One explanation for this effect proposed by researchers Valenzuela & Raghubir (2009), is that we tend to think that products are more popular when placed in the middle of an array.
Spark Effect
Users are more likely to take action when the effort is small.
Ask less, get more. Self-destructing invitation, Limited inbox.
fmfmerian Or passwordless auth, like Pitch. Easier signin, simpler FTUX.
When they are unsure or when the situation is ambiguous, they are most likely to look and accept the actions of others as correct. The greater the number of people, the more appropriate the action seems.
fmfmerian As an example, Buffer highlights the testimonial of a though leader to inspire action in its signup page.
The curiosity gap is the space between what users know and what they want or need to know. Gaps cause pain, and to take it away, users need to fill the knowledge gap.
Miller's Law
Users can only keep 7 items in their working memory.
Less information, the better. But you need to choose the best ones.
Authority Bias
Users attribute more importance to the opinion of an authority figure.
Survey Bias
Users tend to skew survey answers toward what's socially acceptable.
Labor Illusion
Labor Illusion
Loss Aversion
Loss Aversion
We hate losing or letting go of what we have (even if more could be had). Prospect theory says that a loss hurts more than an equal gain feels good. In other words, losing $1,000 will “hurt” more than the joy of gaining $1,000.
fmfmerian Example: The Slite "deferred account creation" relies on the fact that you'll want to confirm your account email AFTER you've set up your account because you won't want to lose what you did.
People experience the sunk cost effect when they keep doing something as a result of previously invested resources (time, effort, money, etc). That effect becomes a fallacy if it's pushing them to do things that won't make them happier.
Below is a list of cognitive biases and design principles for each category.
Browse the full list with the Table of Contents from the menu in the top-right hand corner. Looking for examples and tips for a specific principle? Search it in this doc with the keyboard shortcut Cmd+F.
Hick's Law predicts that the time and the effort it takes to make a decision, increases with the number of options. The more choices, the more time users take to make their decisions.
fmfmerian The time it takes to make a decision increases with the number and complexity of choices.
Hick's Law Examples
In a travel booking app like Airbnb, having too many options can lead to a paradox of choice (and churn!):
Subtle visual or verbal suggestions help users recall specific information, influencing how they respond. Priming works by activating an association or representation in users short-term memory just before another stimulus or task is introduced.
Priming Examples
Priming consists of subtle visuals that influence how we respond. The friendly-looking airport landscape lets the users dream about their next trip increasing the chances of a positive experience:
Brave cleverly mentioned in the previous onboarding step how they block creepy trackers for a safer browsing experience. This primes you to focus on privacy, making you more likely to choose DuckDuckGo instead of Google search. Brave can hence subtly (but respectfully) reduce the brand awareness of their number one competitor: Google.
Total amount of mental effort is required to complete a task.
More
Cognitive Load Definition
Cognitive load is the total amount of mental effort that is required to complete a task. You can think of it as the processing power needed by the user to interact with a product. If the information that needs to be processed exceeds the user’s ability to handle it, the cognitive load is too high.
Cognitive Load Examples
A great example of reducing the load is Tinder's profile onboarding:
Users rely heavily on the first piece of information they see.
More
Anchoring Bias Definition
The initial information that users get affects subsequent judgments. Anchoring often works even when the nature of the anchor doesn't have any relation with the decision at hand. It's useful to increase perceived value.
Anchoring Bias Examples
Tinder's pricing table shows the most expensive subscription plan first (the anchor) so that the other plans look inexpensive in comparison:
Brick and mortar shops often display very expensive items in the front with visible price tags so that the item you end up seeking seems cheaper.
Nudge
Subtle hints can affect users' decisions.
More
Nudge Definition
People tend to make decisions unconsciously. Small cues or context changes can encourage users to make a certain decision without forcing them. This is typically done through priming, default option, salience and perceived variety.
Nudge Examples
While you search for a place to stay, Airbnb nudges you to add a date and number of guests instead of forcing those filter:
Users are less overwhelmed if they're exposed to complex features later.
More
Progressive Disclosure Definition
An interface is easier to use when complex features are gradually revealed later. During the onboarding, show only the core features of your product, and as users get familiar, unveil new options. It keeps the interface simple for new users and progressively brings power to advanced users.
Progressive Disclosure Examples
One of the best examples of progressive disclosure we've ever seen in an onboarding!
Less than 16% of Brave daily active users activate Brave Rewards, despite the fact that it's a great system (users get paid to view ads). This is an example of an advanced feature that's best to defer until later through progressive disclosure. Opting for a more gradual approach might not only improve time-to-value, but also increase the Rewards adoption rate, which generates the majority of Brave's revenues.
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 it 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
More
It's a lot easier to make a choice when we compare similar things. Our brain can quickly evaluate the differences as opposed to when options are different.
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
Social Proof
Users adapt their behaviors based on what others do
More
Social Proof Definition
Social proof is a convenient shortcut that users take to determine how to behave. When they are unsure or when the situation is ambiguous, they are most likely to look and accept the actions of others as correct. The greater the number of people, the more appropriate the action seems.
Social Proof Examples
Entice users to take action by showing the number of people who did it, like Calm does:
People value things more when they're in limited supply
More
Scarcity Definition
While scarcity is typically invoked to encourage purchasing behaviors, it can also be used to increase quality by encouraging people to be more judicious with the actions they take. It can come in different forms: Time-limited, Quantity limited, Access-limited. Never fake scarcity if you don't want reactance!
Scarcity Examples
Uber Eats is one of the rare apps that uses scarcity in a positive way. They offer users to share the costs delivery with other people if they order quickly enough:
Users have a desire to seek out missing information
More
Curiosity Gap Definition
The curiosity gap is the space between what users know and what they want or need to know. Gaps cause pain, and to take it away, users need to fill the knowledge gap.
Curiosity Gap Examples
Morning Brew uses copywriting open loops and split quiz at the end of their email:
Users have a preconceived opinion of how things work.
More
Mental Model Definition
A mental model is an explanation of someone's thought process about how something works in the real world. It is a representation of the surrounding world, which might be accurate or not. What users believe they know about your product changes how they use it.
Mental Model Examples
Trello does a mental model migration by gradually persuading new users that their Trello "cards", "boards" and "lists" are better alternatives to traditional "todo lists":
Users have an innate desire for things they're already familiar with. And the more we experience something, the more likely we are to like it. So, try to use common patterns when creating new experiences.
Familiarity Bias Examples
Superhuman uses familiar keyboard shortcuts to ease the learning curve:
A popular experiment on this effect showed that a 10-stamp loyalty card pre-stamped twice will be completed faster than an 8-stamp one with 0 pre-stamps.
In the case of this trial timeline, getting users to understand that their journey already has started might increase the trial paywall conversion rate.
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
Labor Illusion
People value things more when they see the work behind them.
More
Labor Illusion Definition
Making users wait for something they requested while showing them how it is being prepared creates the appearance of effort. Customers are usually more likely to appreciate the results of that effort. This is also called the "KAYAK Effect" (based on the travel booking site that used that tactic).
Labor Illusion Examples
The first time you see your potential matches after you complete your profile, Tinder shows the results so quickly that you might doubt of their quality:
KAYAK (travel booking site) once delayed the time search results page to show that it is "crunching data".
TurboTax showed "validation and analysis" screens when you submit your taxes.
Default Bias
Users tend not to change an established behavior.
More
Default Bias Definition
Unless the incentive to change is compelling, people are more likely to stick to the default situation presented to them. This is also called the Status Quo Bias. It can be a powerful actor when trying to change behaviors.
FlFlorent This saves your brain mental resources and avoiding stressful decisions.
Some subscription companies exploit this bias unethically by concealing:
…subscription reminders
…incentives to change (e.g., cost)
…shortcuts to cancel (Fitt's Law)
That's why many customers keep their subscriptions active (e.g., gym, Peloton) even if they barely use them. They are considered Zombie Customers.
Default Bias Examples
Uber Eats' default option is to NOT provide you with disposable items that pollute:
When users invest themselves, they're more likely to come back.
More
Investment Loops Definition
People invest time, money, information, or effort into a product in anticipation of future benefits. It makes them more likely to return because of the increase in perceived value. When executed properly, user investments load the next trigger to use your product.
Investment Loops Examples
Morning Brew could use personalization to get people to customize the stocks displayed at the top.
People prefer to avoid losses more than earning equivalent gains.
More
Loss Aversion Definition
We hate losing or letting go of what we have (even if more could be had). Prospect theory says that a loss hurts more than an equal gain feels good. In other words, losing $1,000 will "hurt" more than the joy of gaining $1,000. Loss aversion can also lead to sunk cost fallacy. (Related: Endowment Effect)
Loss Aversion Examples
Your fear of losing the Duolingo gems you wager encourages you to maintain the practice streak to which you committed:
When you go over the usage limit, Zapier reminds you that you have 30 days to upgrade before you lose your data. It's a powerful incentive to take action now:
Trello's "deferred account creation" relies on the fact that you'll want to confirm your account email AFTER you've created boards, lists and cards because you won't want to lose them.
Users tend to be consistent with their previous actions.
More
Commitment & Consistency Definition
When users are asked to do something, their brain instinctually perceive it as a threat. The smaller the initial ask, the smaller the fight or flight response and the more likely they are to agree to gradually bigger requests. Especially since the brain likes to be consistent with its previous actions. It's part of the reason why multi-step forms can perform up to 271% better than a big single-step form.
Commitment & Consistency Examples
Tinder's onboarding splits their signup form in 6 single-question steps to leverage the power of micro-commitment:
Depending of the visitors context, some of our Growth.Design newsletter opt-in prompts use two steps. We AB tested it against a single step (email field) variante and it generated a lift of +11%.
Sunk Cost Effect
Users are reluctant to pull out something they're invested in.
More
Sunk Cost Effect Definition
People experience the sunk cost effect when they keep doing something as a result of previously invested resources (time, effort, money, etc). That effect becomes a fallacy if it's pushing them to do things that won't make them happier.
Sunk Cost Effect Examples
Duolingo encourages you to bet gems if you think you can keep a practice streak for one week:
Netflix: Have you ever watched a boring movie until the end, simply because you started it? That's sunk cost fallacy in action.
World of Warcraft MMORPG: millions of players keep playing (and paying 15$/month) partly because they've already invested so much time and money in the virtual game.
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.
More
When we perceive that our freedom of behavior is being threatened, we develop an intense emotional response resulting from a restriction of our ability to make decisions.
If people figure out what YouTube is planning, there's a real chance reactance could impact their overall conversions negatively.
When you take away too much of a person's behavioral freedom, it backfires and increases resistance to persuasion. That's why gently nudging a behavior is often better than forcing it.
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 credits for positive events and blame others if negative.
Pareto Principle
Rougly 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 user partially create something, they value it way more.
Planning Fallacy
People tend to underestimate how much time a task will take.
Memory
Provide Exit Points
Invite users to leave your app at the right moment.
More
Provide Exit Points Definition
Exit points are meant to respect people's time. They are opportunities to "put down" the product when users feel they have reached something. They are critical to an overall experience when you want to avoid product fatigue and reactance.
Your brain heavily weighs the peaks and the end of an experience.
That's why it's important to allow users to disengage from your product with a sense of completion.
Customers churn for different reasons, some of which you simply can't control.
So just like any relationship, the key is to:
Remain ethical
Treat people with respect
Give them a good last impression
Peak-End Rule
People judge an experience by its peak and how it ends.
More
FlFlorent If you want people to change or adopt a new behavior, one of the best ways to achieve this is by making sure the end of their experience is memorable.
Peak-end Rule Definition
Users don't merely evaluate an experience based on the average or a sum of all the micro-experiences. Instead, their brain heavily weighs the peaks (high or low) and the end of the experience. Peaks—when pleasant—often correspond to memorable delighters sprinkled into the user journey.
Peak-end Rule Examples
After you pay to upgrade your account, Zapier shows animated confettis as a way to celebrate (and rightfully take your focus away from the hundreds of dollars you just paid!):
Duolingo doesn't provide a clear exit point. This makes the "end" of your in-app experience feel like you're abandoning your learning process (even if you've achieved your goal):
Users engage more with things appealing to multiple senses.
More
Sensory Appeal Definition
Why are we tempted to eat sweets when walking by a bakery in the morning? The smell out of the oven is strong enough to make us stop. The sights, sounds, feels, tastes, and smells of products are designed to engage users' senses. And when multiple senses are engaged, people are more likely to create an emotional connection with the brand.
Sensory Appeal Examples
Uber Eats "dry" menu could use sensory appeal to increase desirability:
People remember incomplete tasks better than completed ones.
More
Zeigarnik Effect Definition
Lewin’s field theory states that a task in progress creates task-specific tension. This tension is relieved when the task is completed, but if the task is interrupted, it stays. That tension makes relevant information more accessible and more easily remembered.
Zeigarnik Effect Examples
Duolingo shows you an incomplete progress bar to encourage you to reach your daily practice goal:
Users value something more if they feel it's theirs.
More
Endowment Effect Definition
Users are more likely to want to keep something that they own than acquire that same thing when they don't own it. They tend to overvalue the things they own, regardless of their objective market value. (Related: Loss Aversion)
Endowment Effect Examples
Trello encourages you to personalize your board through a well-timed nudge so that you perceive it more like "your" workspace:
Animal attacks at a young age can sometimes turn people into vigilantes.
More
The Batman Curse Definition
Studies have shown that a child's brain can produce unique hormones in reaction to dangerous animal encounters. During puberty, 1 out of 10 children will start seeing the effect of ADN alterations. Their brain becomes wired to look for justice.
The Batman Curse Examples
A recent surge of vigilantes cases in Watopia alerted authorities to investigate the Batman curse. One individual was arrested and revealed that he was attacked by bats when he was 6 years old.
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.
More
Delighters Definition
We remember and respond favorably to small, unexpected and playful pleasures.
:hear
Superhuman has functions that aren't only useful but just a pure delight.