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.
Below is a list of cognitive biases and design principles (with examples and tips) for each category. Let’s dive right in.
PS: Don’t have time to read the whole list? Just get the cheat sheet.
Hick's Law
More options leads to harder decisions
Hick's Law Definition
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.
Hick's Law Examples
- In a travel booking app like Airbnb, having too many options can lead to a paradox of choice (and a churn!):
- Trello's 3rd signup step has a dropdown with 15 options. That makes it hard to pick one:
- Duolingo's list of lessons can sometimes be overwhelming:
- Zapier showed too many navigation links during their upgrade flow which distracts you from crucial checkout steps:
Hick's Law Checklist
- Find an area where you have a lot of options or a lot of repetitions.
- Try to either reduce the number of options or find ways to hide items. (Do they all need to be displayed at once? #progressive disclosure)
- If you can't minimize the options, try to put them in an easily skimmable order and make sure the items are familiar; else, it won't work.
Confirmation Bias
People look for evidence that confirms what they think
Confirmation Bias Definition
People tend to search for, interpret, prefer, and recall information in a way that reinforces their personal beliefs or hypotheses.
Confirmation Bias Examples
- In times of crisis it's hard not to look for what we want to believe in:
Priming
Previous stimuli influence users' decision
Priming Definition
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
- The friendly-looking airport landscape lets the users dream about their next trip increasing the chances of a positive experience:
- Superhuman's onboarding includes a priming on the fact that you'll receive some helpful onboarding emails from their CEO
- Anti-Example: Tinder misses a great opportunity to prime new singles during the onboarding:
Cognitive Load
Total amount of mental effort that is required to complete a task
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:
- Hopper's results page has loads of information to parse, making the task of choosing a date harder:
- Mario Kart's home page is packed with graphics and gizmos. However, it wasn't random, find out why they designed it that way:
Anchoring Bias
Users rely heavily on the first piece of information they see
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
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:
- The default purchase option on some Amazon products is a “subscription”. They incentivize this automatic recurring purchase by offering a discount:
Progressive Disclosure
Users are less overwhelmed if they're exposed to complex features later
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!
- Hopper only shows the bare minimum features when you start searching for a flight:
Fitt's Law
It's easier to aim the bigger the target is
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 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
Centre-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
Scarcity
People value things more when they're in limited supply
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:
- Dark Pattern: Mario Kart offers Tours and special items for a limited time to increase conversion rates:
- Dark Pattern: Sleepzy uses unjustified scarcity to pressure new users into buying:
Curiosity Gap
Users have a desire to seek out missing information
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:
- Tinder shows blurry pictures of people who want to “match” with you:
Mental Model
Users have a preconceived opinion of how things work
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”:
Familiarity Bias
People prefer familiar experiences
Familiarity Bias Definition
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:
- Spotify's podcast play screen is very similar to their song play screen, which eases adoption:
- Remember Snapchat's big redesign? Well its users remember very well… And they didn't like it! A strong case of familiarity bias.
Halo Effect
People judge things (or people) based on their feelings towards one trait
Miller’s Law
Users can only keep ±7 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
Cheerleader 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 setup for themselves
Survey Bias
Users tend to skew survey answers towards what's socially acceptable
Cognitive Dissonance
It's painful to hold two 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
Labor Illusion
People value things more when they see the work behind them
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
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.
Default Bias Examples
- Uber Eats' default option is to NOT provide you with disposable items that pollute:
- Some Airbnb filters are OFF by default, which can lead to confusion as to what will happen if you switch them ON:
- Amazon uses status quo bias to encourage behaviors that aren't necessarily to the user's advantage:
Investment Loops
When users invest themselves, they're more likely to come back
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
- Strava encourages you to set personal goals, which will serve as a reminder for you to exercise later on:
- Spotify could encourage users to invest time to take podcast notes in-app:
Loss Aversion
People prefer to avoid losses more than earning equivalent gains
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.
Commitment & Consistency
Users tend to be consistent with their previous actions
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 before 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:
- Duolingo email notifications cleverly use the fact that you committed to practice a language to ask you if you “still want to learn it”:
- 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 of something they're invested in
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
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 credits 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 user partially create something, they value it way more
Planning Fallacy
People tend to underestimate how much time a task will take
Provide Exit Points
Invite users to leave your app at the right moment
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. (Related to: Peak-End Rule)
Provide Exit Points Examples
- Duolingo's experimental redesign to provide more exit points
- Mario Kart Tour missed an opportunity to allow players to gracefully leave their app:
Peak-End Rule
People judge an experience by its peak and how it ends
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):
Sensory Appeal
Users engage more with things appealing to multiple senses
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:
- Superhuman's experimental redesign could use sounds that act as a reward loop to reinforce behaviors:
Zeigarnik Effect
People remember incomplete tasks better than completed ones
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:
Endowment Effect
Users value something more if they feel it's theirs
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:
The Batman Curse
Animal attacks at a young age can sometimes turn people into vigilantes
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.
- Who needs a reference? Everybody knows it’s true, Fail·Design (2020)
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
Product & Psychology Resources
If you want to learn more about behavioral psychology and mental models, we highly recommend you take a look at these resources:
Cognitive Biases Codex
The four categories of our list come from Buster Benson's work
Description
We want to give a special shout out to Buster Benson. He did an impressive job with the categorization of cognitive biases which led him to build a massive Codex.
The four categories of this list are based on his research, so we want to make sure he gets the credit for this hard work.
Every single person, including myself, has many implicit associations that lead to bias that they can’t fully eradicate in themselves. It’s more effective to accept that fact, and account for it by being transparent about it, than to try to hide it.Buster Benson, author of "Why Are We Yelling?"
Super Thinking
The big book of mental models and cognitive biases (Gabriel Weinberg)
Description
Gabriel Weinberg (CEO of DuckDuckGo), co-authored a WSJ bestseller book that inspired us a lot: Super Thinking: The Big Book of Mental Models.
He recently did a video interview with Jordan Harbinger where he discussed the importance of mental models and cognitive biases. We completely agree with him when he says:
Knowing the names of cognitive biases and mental models is important. That’s because once you have a name for something, you can start to spot it in the real-world. And once you start to spot it, then you can really start to use the tools [and reap the benefits].Gabriel Weinberg, CEO of DuckDuckGo
Hooked
How to build habit-forming products (Nir Eyal)
Description
This book dives deep into the psychology of habits. It’s filled with user retention loops and examples.
Nir Eyal is the best-selling author of Hooked: How To Build Habit-Forming Products and Indistractable.
He’s doing amazing work at the intersection of psychology, technology, business and ethics.
Influence
The psychology of persuasion (Robert Cialdini)
Predictably Irrational
The hidden forces that shape our decisions (Dan Ariely)
Cognitive Biases Cheat sheet
We took the time to summarize each principle in one line.
They are all in a free cheat sheet of cognitive biases principles.
You can download this cheatsheet as a PDF here.
Use it as a user empathy reminder while you build a feature.
(…or print and pin it on your office/cubicle wall once COVID-19 is done!)
We all have a responsibility to build ethically-designed products and services to improve people’s lives. Growth.Design’s list of cognitive biases and psychological principles is a great reference for any team committed to improving their customers’ user experience. Dan & Louis-Xavier’s comic book case studies show you how.Nir Eyal, bestselling author of Hooked and Indistractable
Now It’s Your Turn
So which principle are you going to try next?
Are there missing elements we should add to the list?
We reply to everyone so…
Let us know by leaving a comment below! 👇
👥Social Proof
Users adapt their behaviors based on what others do
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