Anchoring Bias
The tendency to rely too heavily on the first piece of information offered (the "anchor") when making decisions.
In Design: Displaying a higher "original" price next to a discounted price makes the discount seem like a better deal.
Choice Overload
A cognitive process in which people have a difficult time making a decision when faced with many options.
In Design: Reducing the number of CTA buttons on a landing page to increase conversion rates.
Commitment & Consistency
The tendency to behave in a manner that is consistent with our past behaviors or commitments.
In Design: A multi-step onboarding process where each step is a small commitment makes users more likely to complete the entire flow.
Default Bias
The tendency to stick with the pre-set or default option, as it requires the least amount of effort.
In Design: Pre-selecting the most popular subscription plan or a "recommended" setting can significantly influence user choice.
Framing Effect
People decide on options based on whether the options are presented with positive or negative connotations; e.g. as a loss or as a gain.
In Design: "90% fat-free" sounds better than "10% fat". "Save $5" vs "Avoid losing $5".
Hick's Law
The time it takes to make a decision increases with the number and complexity of choices.
In Design: Simplifying navigation menus or breaking complex forms into smaller steps to reduce cognitive load.
Loss Aversion
The tendency to prefer avoiding losses to acquiring equivalent gains. The pain of losing is about twice as powerful as the pleasure of gaining.
In Design: Phrasing like "Don't miss out!" or showing what a user will lose by downgrading a plan is more powerful than showing what they will gain.
Paradox of Choice
Having too many choices can lead to decision paralysis and dissatisfaction, rather than feeling empowered.
In Design: A long dropdown with 50 options can be overwhelming. Better to use smart defaults, search, or break it down into categories.
Scarcity
The tendency to place a higher value on things that are scarce and a lower value on things that are abundant.
In Design: "Only 2 left in stock!" or "Limited time offer" creates a sense of urgency that encourages immediate purchase.
Status Quo Bias
The preference for the current state of affairs. Any change from the baseline is perceived as a loss.
In Design: Users may resist a major redesign, even if it's objectively better, because they are comfortable with the existing layout.
Sunk Cost Fallacy
The phenomenon where a person is reluctant to abandon a course of action because they have invested heavily in it, even when it is clear that abandonment would be more beneficial.
In Design: Users might continue through a long, poorly designed checkout process simply because they've already filled out three pages of forms.
Availability Heuristic
The tendency to overestimate the likelihood of events with greater "availability" in memory, which can be influenced by how recent, unusual, or emotionally charged the memories are.
In Research: Focusing on the most recent user interview or the most vocal participant, ignoring the broader data set.
Banner Blindness
The tendency of users to ignore page elements that they perceive to be advertisements, even when they are not.
In Design: Important information placed in areas that resemble ad banners (like top-right sidebars) is often overlooked by users.
Change Blindness
A phenomenon where a person viewing a visual scene fails to detect large changes in the scene if they are not cued.
In Design: If adding an item to a cart only updates a tiny number without animation, users may not notice the change happened.
Hindsight Bias
The tendency of people to overestimate their ability to have predicted an outcome that could not possibly have been predicted.
In Research: Stakeholders claiming "I knew users would struggle with that" after seeing usability test results, despite approving the design earlier.
Peak-End Rule
People judge an experience largely based on how they felt at its peak (i.e., its most intense point) and at its end, rather than the average of every moment.
In Design: Adding a delightful animation or a helpful success message at the end of a task can leave a positive lasting impression.
Recognition Over Recall
It's easier for people to recognize things they have previously experienced than it is to recall them from memory.
In Design: Showing recently viewed items is easier for users than making them search for the item again from memory.
Serial Position Effect
Users have a propensity to best remember the first and last items in a series.
In Design: Placing the most important actions or information at the beginning or end of a list or navigation menu.
Von Restorff Effect
Also known as the Isolation Effect, predicts that when multiple similar objects are present, the one that differs from the rest is most likely to be remembered.
In Design: Making the primary Call to Action (CTA) button a different color or size than secondary buttons.
Zeigarnik Effect
People remember uncompleted or interrupted tasks better than completed tasks.
In Design: Using progress bars or "profile completeness" indicators to encourage users to finish a task.
Bandwagon Effect
The tendency for individuals to adopt certain behaviors or beliefs because many others are doing so.
In Design: Showing "trending" or "popular" items to encourage adoption, leveraging the power of social proof.
Social Proof
The psychological phenomenon where people assume the actions of others in an attempt to reflect correct behavior for a given situation.
In Design: "Best Seller" tags, testimonials, or "50 people are viewing this item" notifications.
Cognitive Load
The total amount of mental effort being used in a person's working memory. High cognitive load can lead to errors and frustration.
In Design: Complex forms with many fields increase cognitive load. Break them into smaller, logical steps to reduce it.
Confirmation Bias
The tendency to search for, interpret, favor, and recall information in a way that confirms or supports one's prior beliefs or values.
In Research: Asking leading questions like "How much do you love this feature?" instead of "What are your thoughts on this feature?"
Endowment Effect
The tendency for people to ascribe more value to things merely because they own them.
In Design: Free trials allow users to feel ownership of a product, making it harder for them to give it up when the trial ends.
Familiarity Bias
The tendency to prefer familiar things, people, or experiences over unfamiliar ones.
In Design: Using standard icons and UI patterns (like a shopping cart icon) reduces the learning curve and makes users feel more comfortable.
Fitts’s Law
The time to acquire a target is a function of the distance to and size of the target.
In Design: Make important buttons large and place them close to where the user's attention or cursor is likely to be (e.g., thumb zone on mobile).
Mental Model
People have models of how things work based on past experiences. When a system doesn't match their model, it causes confusion.
In Design: If a user expects a 'Save' button but the app auto-saves, they may feel anxious and unsure if their work is safe.
Mere Exposure Effect
The tendency to develop a preference for things merely because they are familiar with them.
In Design: Repeatedly exposing users to a brand logo or a new feature (without being annoying) can increase their positive feelings towards it.