Psychologists studying the functioning of the human brain found out a long time ago that it has a tendency to take shortcuts and simplify tasks. By nature, our brain just doesn't want to fatigue itself. This is especially true today when many of us experience cognitive overload. A brain overwhelmed with too much information it can't process effectively tries to find a way to make things easier. The result? Cognitive biases.
What are cognitive biases?
Cognitive biases are our brain's ways of processing large amounts of information and making decisions faster. Since this is a kind of mental shortcut that often happens unconsciously, cognitive biases can lead to incorrect conclusions and decisions.
Cognitive biases result from the mechanisms of how our brain operates, over which we do not have full control. They are driven by System 1, which relies on heuristics and emotional evaluations, functioning in an automatic and simplified manner. However, we do have the ability to notice and respond to cognitive biases through System 2. Unfortunately, this often doesn’t happen because activating System 2 requires additional effort.
It’s worth noting that the term cognitive biases was coined by Daniel Kahneman and Amos Tversky, who are also the authors of the widely recommended book Thinking, Fast and Slow. This book provides deeper insights into cognitive biases and the Systems 1 and 2.
Why is this important in UX?
Understanding cognitive biases provides designers with insights into how users make decisions, often unconsciously and intuitively.
With this knowledge, we as designers can influence how users process and remember presented information, impact decision-making processes, learning of interfaces, and ultimately the evaluation, satisfaction, and overall experience of using an application or website. Examples of this influence can be found in the following description of cognitive biases.
Examples of Cognitive Biases
The list of cognitive biases is constantly expanding, and it's impossible to cover them all in a single article. Instead, I’ve selected a few that I believe are particularly relevant for designers. Additionally, I’ve included a list of cognitive biases worth exploring on your own.
I’ve organized the biases into four categories that Buster Benson and John Manoogian III proposed in the Cognitive Bias Codex.
What should we remember
Cognitive biases in this category relate to how the human brain decides which information to remember. These are often standout elements or generalizations that require less mental effort to commit to memory.
Negativity bias
This is a tendency to focus on negative emotions. We more easily remember negative emotions compared to positive ones.
Users of our products are quicker to recall any errors, slowdowns, or difficulties they encounter rather than the positive experiences they've had. This means that negative experiences can overshadow the positive ones, affecting their overall perception of the product or service and reducing their satisfaction. This can ultimately lead to users discontinuing their use of the product or service. As designers, we should aim to eliminate any pain points that users might encounter.
Peak-end rule
People evaluate their experiences based on two moments: the most intense, exciting, or surprising moment and how the experience ended.
The same applies when assessing the experience of interacting with a product or service. Strong, positive moments and a good ending can cause users to rate the experience as positive, even if the other moments are somewhat weaker.
Congratulations upon achieving a goal in a fitness app, concluding a purchasing process with a summary containing important information and a thank you for the purchase, or small animations and micro-interactions can particularly stick in memory as positive experiences.
Serial recall effect
When exposed to information presented in a specific sequence, such as a list of items, the human brain tends to remember those at the beginning and the end more easily, while those in the middle are the least memorable.
This is why we should keep in mind to place the most important information at the beginning and the end of a sequence. This could include navigation elements, sections on a website, a product list in an online store, a list of product features, or even steps in an onboarding process.
In the context of the serial recall effect, it’s also worth exploring the primacy effect, which focuses on remembering the first items in a list, and the recency effect, which explains the retention of the last items.
Spacing effect
The human brain is better at remembering information that is broken down into smaller chunks or spread out over time.
When users are exposed to a large amount of information, their ability to remember it decreases. It’s much easier for us to learn something by dedicating 30 minutes a day over several days than by spending several hours on it in one day.
This is especially valuable in tutorials and onboarding processes, where we want to guide the user through a new interface or teach them how to use a program in a way that doesn’t overwhelm them with new, difficult information, helping to prevent them from giving up.
Other biases worth checking out
False memory
Source confusion
Misattribution of memory
Stereotypical bias
Implicit stereotype
Fading effect
Appeal to novelty
Google effect
Tip of the tongue phenomenon
Absent-mindedness
Levels of processing effect
Too much information
When faced with an overwhelming amount of information that we can't process, the human brain must decide which details to remember and which to discard.
Von Restorff effect
The isolation effect says that people tend to remember elements that stand out from others, e.g., through color, shape, or size. As a result, distinctive elements on a website, such as buttons, can significantly increase their effectiveness.
When designing, we can use this effect to capture users' attention. Highlighting key elements against the rest will make them noticed faster and improve their memorability. Additionally, properly emphasizing elements can help users understand the content, find important features, or navigate a website. This can be done by visually highlighting important content or making call-to-action (CTA) buttons stand out from other elements on the page. Unconventional shapes and subtle animations can also be effective in drawing users' attention to key content.
Anchoring bias
People have a tendency to rely on the first piece of information they receive, which then becomes the basis for their decisions and assessments.
In design, anchoring bias appears in situations where two prices are compared (a higher and a lower one). The higher price becomes the reference point for the lower one, making the latter seem much more attractive. This also applies to maintaining consistency on websites, as exposure to the first elements creates an attachment to how they function, leading to the expectation that all other elements—such as those with the same color—will work similarly (e.g., buttons and links).
Anchoring bias can also occur in two other situations. First, if we make a very good first impression, it becomes the reference point when encountering small flaws later on, possibly leading to a more favorable evaluation of a product or service. Second, when the first impression sets high expectations that are not later met, it can result in disappointment and abandonment.
Framing bias
The way information is presented affects how it's interpreted and evaluated, which means that presenting information appropriately can influence decision-making.
In design, framing bias is often used when informing users about prices and the benefits associated with them. For example, the statement "The monthly subscription costs $10" can be replaced with "Get full access for just $10 a month," which sounds more attractive. Another example is highlighting that a yearly subscription saves 25% rather than emphasizing that you have to pay for the entire year upfront. This also applies to how product reviews are presented (a rating with the number of reviews can be perceived much more positively than just the rating alone) or how information is conveyed in a way that stimulates specific emotions, often negative.
It's worth noting that framing bias allows for easy manipulation of users and encourages them to make decisions that may not be in their best interest.
Availability heuristic
This is a phenomenon in which people make decisions based on the information that comes to mind most easily. If some information is easily accessible, e.g. through strong emphasis or frequency of occurrence, users will consider it more important or probable.
In design, we can leverage this by ensuring that key features and important information are easily accessible and visible. This increases their usage and reduces cognitive load, as important information is readily available. Additionally, it shortens the time needed to review content and make decisions, which overall improves the user experience.
Confirmation bias
People tend to select information that confirms their previous beliefs or expectations while ignoring other information that might contradict those beliefs.
In design, this can be used to intentionally display information that aligns with what users feel or expect from a product in order to increase their engagement and loyalty.
Confirmation bias also affects us as designers, for example, during data analysis and user interviews, where we may ask questions in a way that confirms our beliefs or focus on usability test results that support the validity of our design. The same risk applies when receiving feedback on our designs; when we become too attached to our solutions, we may dismiss constructive criticism, which can lead to a lower-quality outcome.
Confirmation bias is also visible on social media, where users are shown content that matches their beliefs, often reacting to it with greater engagement. This is a significant threat because it easily creates information bubbles and facilitates the spread of fake news.
Other biases worth checking out
Bizarreness effect
Humor effect
Baader-Meinhof phenomoenon
Empathy gap
Weber-Fechner law
Contrast effect
Naive cynicism
Naive realism
Selective perception
Expectation bias
Attentional bias
Not enough meaning
These cognitive biases reveal how the human brain behaves in situations where it lacks complete information and must piece everything together on its own.
Planning fallacy
This is a phenomenon that shows how people tend to underestimate the time, effort, and resources needed to complete a task while overestimating their own abilities.
For designers, this can apply to at least a few situations. One of them is allocating insufficient time to complete a task, often underestimating the amount of time needed, both on the part of designers and the entire team. Additionally, teams often set overly ambitious goals and fail to anticipate problems that may arise along the way. They also mismanage the resources needed to complete a project, having too few, which causes delays and negatively impacts the quality of the final outcome.
Bandwagon effect
This effect shows that people are more likely to make decisions or adopt certain beliefs when they see others doing the same.
In design, this effect is used in various situations where we inform users about, for example, how many people have already bought a product or currently have it in their cart, as well as in all kinds of recommendations based on other users' or friends' activities. This effect is also visible in social media, where the number of likes or followers can subconsciously suggest that something is worth paying attention to. Additionally, you can observe it in the number of ratings and reviews for a service or product - if they're positive and there are many reviews, it can attract more user attention. All of this can increase conversion rates and build greater trust in the product or service.
Aesthetic usability effect
Aesthetic products are perceived as more useful even when they're just as functional as their less attractive counterparts.
In design, products with a well-designed, aesthetically pleasing interface significantly increase the likelihood of being rated as offering a better experience, ease of use, and overall quality, even when the product is not actually superior to its less visually attractive competitor.
Of course, it's important to remember not to prioritize aesthetics over usability and solving real needs and problems. Even the best-designed interface can't cover up a lack of functionality or failure to deliver real value to users, as such products are doomed to fail from the start. First address user needs, then focus on aesthetics.
Anecdotal fallacy
This is a cognitive bias where we tend to draw conclusions based on single cases.
Designers should be particularly cautious of this cognitive bias when analyzing user feedback or research results. It's important to ensure we’re not overly focused on individual conclusions or opinions or, for example, planning to implement changes or new features based on the feedback from just one or two users without considering whether the issue affects a larger group.
Relying on single cases can lead to designing for a very narrow audience, which may not be beneficial for business goals or the available resources within the company.
Curse of knowledge
This refers to the difficulty of imagining not having certain information or knowledge.
This is often seen, for example, during conversations between less experienced designers (but not only them) and stakeholders or clients who use specialized terminology mainly known to designers. It can also be observed in designed products where users lack proper help and tutorials because it seems that the interface will surely be understandable to all users, just as it is for the designers.
All of this can lead to problems, such as communication issues within a team or with non-technical people, as well as a decrease in the usability of products and overall satisfaction with using them.
Other biases worth checking out
Halo effect
Mental accounting
Self-consistency bias
Outcome bias
Spotlight effect
Not invented here syndrome
Group attribution error
Essentialism
Functional fixedness
Insensitivity to sample size
Hindsight bias
Recency illusion
Anthropomorphism
Survivorship bias
Authority bias
Clustering illusion
Need to Act Fast
These cognitive biases arise in situations where we need to make decisions, often quickly, and act under pressure.
Loss aversion
This cognitive bias refers to the fact that we feel losses more intensely than gains of the same value. For example, losing $50 feels much more significant than gaining $50.
This effect appears in situations where users are informed more about what they might lose by giving up or not choosing certain options rather than about the associated benefits or in situations where they're informed about benefits related to making a decision - for example, not canceling a subscription to receive or maintain a current, better price. The benefit is the subscription discount, while the loss is losing that discount.
Loss aversion bias is also visible in online stores, for example, in time-limited promotions like “20% off today only.” Users may make quicker decisions out of fear of losing the discount. It also applies when we inform users that a product can be returned or exchanged, which can reduce the feeling of loss if the purchase turns out to be unsuccessful, leaving them with an unwanted product and lost money.
Insurance sales are also a good example. Purchasing a specific package is meant to protect us against future losses.
Decoy effect
This is a phenomenon where a user's decision can be influenced by presenting an unattractive option to make the other options appear more appealing.
In design, this effect is used to influence user decisions. For example, encouraging them to choose a more advantageous subscription plan in streaming services or SaaS apps, or to purchase an airline ticket with additional options.
On the other hand, it can also be a tool used when presenting our designs, especially when there's a risk that the proposed best solutions may not be selected. Adding a third, noticeably worse option increases the attractiveness of the previous two options.
Sunk cost fallacy
This is the tendency to continue actions simply because we have already invested time and energy into them. It often leads to continuing activities that provide no real benefits.
This effect is often visible in the products and services we use when we are encouraged to return to using an application that we have already spent a lot of time on, even when it does not provide us with any value or in situations where we want to abandon a long process, e.g. a purchase, then we often complete the process anyway because we have already invested a lot of energy in it. This leads to irrational decisions that can be beneficial to the organization because they often come down to the fact that the user will continue to use the application or make a purchase.
This cognitive bias is also visible in teams creating products and services. Companies often don't want to abandon the development of their products or services or give up on implementing projects that are taking much longer than planned. The organization prefers to continue the project because they've invested a lot of time and money into it rather than shutting it down even though it won't bring any benefits.
Default bias
This cognitive bias shows that people prefer default options, even if other options might be more beneficial to them, just to avoid the effort and time required to actively choose a different option.
Thanks to this cognitive bias, we can save users' time and energy by reducing the number of decisions they need to make, providing them with well-configured default options - for example, product configurations. However, this effect is often used to achieve business benefits, such as defaulting to the more expensive option among available choices or selecting other options that are more advantageous for the organization - like automatically enabling all notifications.
False consensus effect
People believe that others share their beliefs and think the same way they do.
As designers, we can fall into the trap of assuming that others have the same problems and needs as we do, which leads us to create solutions based on our own beliefs that may not align with the actual needs of users. This also applies to user behaviors in products, where we may assume that users will behave the same way we do, resulting in inefficient solutions. As designers, we should be careful not to rely on our own beliefs and opinions but rather base our work on information gathered from users through appropriate research methods.
However, designers aren't the only ones who fall into this trap. This is often seen during conversations with clients who are strongly convinced they know users' problems and needs, have ready-made solutions, and don't see the need to conduct proper research with the target group.
Other biases worth checking out
Less is better effect
Social desirability bias
Occam’s razor
Delmore effect
Reactance
System justification
Backfire effect
Zero risk effect
Generation effect
Appeal to novelty
Hyperbolic discounting
Identifiable victim effect
Fundament atribbution error
Dunning-Kruger effect
Optimism bias
False consensus bias
Unit bias
Self-serving bias
Cognitive Biases and Ethics
It’s worth addressing the ethical implications in the context of cognitive biases. As I mentioned earlier, understanding cognitive biases allows us to influence users' behaviors and decisions. I also provided a few examples (and there are many more) where it’s easy to manipulate user decisions in ways that benefit only the product or service owners.
I believe that as designers, we should use this knowledge in a way that benefits users, avoiding its exploitation for manipulative purposes that lead to personal gains at the expense of the user.
When leveraging cognitive biases, we should always consider the goals for which they are used. This approach enables us to create better products, deliver improved user experiences, and build trust among our audience.
Resources
Cognitive Bias Codex by Buster Benson and John Manoogian III
106 Cognitive Biases & Principles That Affect Your UX by Growth.design
Pocket biases by Buster Benson
Thinking, Fast and Slow by Daniel Kahneman and Amos Tversky
Cognitive load in UX Design by Fundament.design
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Great post Mateusz! Definitely saving this as a go-to reference for when I need a quick refresher. It’s a must-read for designers who want to understand the factors that drive human decision-making and want to apply that to the experiences they are designing.
It's interesting, that with all that knowledge, two years later, mobile operating systems in hands of organized people offer them a totally unreadable mosaic of little icons instead of real buttons.