The Cognitive Bias Codex, by Buster Benson, is a visualization of over 200 cognitive biases, offering an overview of how our minds work. Inspired by his childhood, Benson developed the Codex to help others understand and mitigate the influence of biases. The Codex encourages critical thinking and greater self-awareness, empowering individuals to make more informed and balanced decisions. (cf. Emergent Thinkers) It separates all biases into 4 problem groups: Too much information, not enough meaning, need to act fast & “What should we remember?”. This and the following blogposts will explain one of the four categories, reflecting on the different biases within them and their impact on UX work.
Each category shows a broad problem definition, which is then split up into different behaviors we show or have. Below these there are effects or biases that explain why we have these behaviors, since they are a combination of all our biases and influences from our surroundings. To make this shorter and easier to read, I will not go into detail on every single bias and effect there is. (At least not in this blog post. ;D)
01 Information Processing
This category of the cognitive bias codex highlights how our brains handle the massive amounts of data we encounter daily. These biases influence how we collect, interpret, and remember information, often simplifying them to help us make decisions faster. While these mental shortcuts can be useful, they also shape our beliefs, judgments, and actions in ways we may not fully realize. Exploring this category helps to uncover hidden filters in our thinking, enabling us to better evaluate information, recognize distortions, and make decisions with more clarity. (cf. Gust de Backer)
01.1 Primed or Repeated Information
Our attention is drawn to information that aligns with what we already know. This makes certain details seem more important than others. The list of biases is very long, so here are the five biases I consider most important for UX Design.
- Availability Heuristic
People judge the likelihood of events based on how easily examples come to their mind. This can lead to skewed decision-making, as recent experiences are more easily recalled and seem more common than they actually are. In UX design, using familiar examples or well-known patterns can help users make quicker decisions. (cf. Beyond UX Design C) - Attentional Bias
People tend to pay more attention to certain types of information while ignoring others, based on personal preferences, emotions, or past experiences. This means users are more likely to notice and engage with elements that are emotionally charged, eye-catching, or familiar. (cf. Beyond UX Design D) - Mere-Exposure Effect
People tend to develop a preference for things because they are exposed to them repeatedly. This effect can be used by consistently presenting certain features or brand elements, making users more comfortable and familiar with them. Over time, familiarity can lead to greater trust and engagement. (cf. Beyond UX Design F) - Empathy Gap
People fail to predict how emotions and mental states affect their behavior, leading to misunderstandings. For example, when not hungry, we might rationally predict we would choose a healthy snack, but in a hungry state, we’re more likely to pick something unhealthy. Understanding this gap helps in designing user experiences that anticipate emotional states and provide supportive features or messaging.
(cf. The Decision Lab B) - Omission Bias
Harmful actions are perceived as worse than harmful inactions, even if the consequences are similar. For instance, people may feel less guilty about allowing negative outcomes than if they actively caused harm. Users might prefer passive features, like automatic settings, that avoid perceived responsibility or failure. Designers can use this by considering user preferences for default options or avoiding overwhelming users with too many choices. (cf. The Decision Lab C)
01.2 Attention-Grabbing Details
Unusual or emotional things captivate us, our brains are wired to notice things that are out of the ordinary. These biases make us prioritize spectacle over substance, they show us how we can make important information stand out and make our users remember it.
- Von Restorff Effect (The Isolation Effect)
When multiple similar items are presented, the one that stands out is more likely to be remembered. This can be applied in UX design by making important elements or actions visually distinct. However, it’s crucial to avoid overwhelming users by overusing emphasis and to be mindful of accessibility issues, such as color vision deficiencies or motion sensitivity.
(cf. Laws of UX) - Picture Superiority Effect
People tend to remember pictures better than words, visuals are processed in two ways as images and as associated words, while words are processed only as text. In UX design, using clear, literal images can improve memorability and comprehension. Effective placement of visuals, using unique images, and avoiding abstract visuals are key strategies to take advantage of this effect.
(cf. NN Group B) - Self-Relevance Effect
People are more likely to remember information that they relate to themselves. This bias enhances memory retention when we connect new knowledge to personal experiences. In UX design, leveraging this effect could involve personalizing content, such as customized recommendations or user-centered messages, to improve engagement and retention. For example, presenting content that users can relate to personally, such as reminders tied to their preferences or past behaviors, can make the experience more memorable.
(cf. The Behavioral Scientist D)
01.3 Novelty and Change
Elements that are new to us or in motion naturally capture our attention. However, this can make us overlook stable, ongoing factors that are equally significant.
- Anchoring
This bias occurs where initial information, such as a suggested value, influences subsequent decisions. While anchoring can guide users to make decisions that align with desired outcomes, it can also unintentionally restrict creativity and objective thinking. (cf. Beyond UX Design B) - Distinction bias
This means, that we evaluate options differently when we asses them together or separately. This often leads to misjudgments, when viewing options side-by-side minor differences may seem disproportionately important. For example, comparing two similar products might exaggerate their distinctions. (cf. The Decision Lab A) - Framing Effect
People react differently depending on whether the same information is framed positively or negatively, influencing decisions. For example, a product described as “95% effective” might be more appealing than one described as “5% ineffective,” even though both mean the same. This bias underscores the power of context and language in shaping perceptions and choices.
(cf. The Decision Lab B) - Weber–Fechner Law
The Weber–Fechner law is about how we sense changes, like light, sound, or weight. It says we notice small changes when something is light or quiet, but bigger changes are needed if something is already heavy or loud. For example, if you’re holding a tiny feather and add another, you’ll notice the difference. But if you’re carrying a heavy backpack, adding one feather won’t feel like much. Imagine having a website in a very clean look with very little visual clutter, little changes will be noticed easier, than on a website with a lot of flashing colors and pictures. (cf. The Behavioral Scientist C)
01.4 Confirm Believes
Confirmation bias leads us to favor information that supports what we already think or feel, reinforcing existing opinions and blinding us to contrary evidence. There are a lot of effects and biases listed in this category here are the ones that I consider most important for UX Work:
- Confirmation & Congruence Bias
The confirmation bias describes the tendency to favor information that aligns with existing beliefs, leading to overlooking or dismissing contradictory views. The congruence bias is very similar, it describes the inclination to test hypotheses through direct confirmation, neglecting alternative possibilities, which can result in flawed conclusions. Especially during user testing this could hinder the advance of products. Since the goal is to find the flaws and shortcomings of a product, this could lead to them being overlooked. (cf. Beyond UX Design B, Philosophy Terms) - Expectation Bias (Experimenter Bias)
This describes the tendency for researchers to unintentionally (or intentionally) influence their study outcomes to align with their expectations, potentially skewing results. Since UX designers have to work with a lot of data, this could once again lead to missteps during the design process and the need to redesign the product later. (cf. The Behavioral Scientist A) - Choice-Supportive Bias
The tendency to remember past choices as better than they were, often by attributing positive features to selected options and negative ones to rejected alternatives. This could, on a small scale influence, how users give feedback to researchers after a testing session. Highlighting what went well and neglecting frustrating experiences, which could make a product seem better than it actually is. Paying attention to what people do is important to later compare this to what they said. (cf. The Behavioral Scientist B) - Observer Effect
A phenomenon one is very likely to come across while doing user research. Individuals tend to modify their behavior due to being observed, which can impact the authenticity of observed actions. Which is totally understandable, you wouldn’t want to be perceived as stupid or incapable in front of another person. (cf. NN Group A)
01.5 Spotting Flaws
It’s easier to spot mistakes or biases in other people than our own, making us more critical of others and less about our own behavior. The codex depicts three biases in this subcategory:
- Bias blind spot & Naive realism
(I have already written a blog post about this bias ;D)
We tend to think, that we see the world objectively (as it really is) and others don’t. We are convinced or information is correct and others who don’t share our views are misinformed or biased. Recognizing naïve realism helps us appreciate diverse perspectives and approach disagreements with empathy. Which is a key ability for UX designers in my book.(cf. Jakob Schnurrer) - Naive cynicism
We mistakenly believe others are more selfish than they actually are, often misinterpreting their intentions. This bias can strain relationships, create mistrust, and hinder collaboration, especially in team settings. Practices like active listening, open communication, and team-building help prevent misunderstandings and promote a more supportive environment.
(cf. Beyond UX Design A)
