106 Principles of Product Design Psychology
106 Cognitive Biases & Principles That Affects the User Experience of your Product.
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.
Users filter out a lot of the information that they receive, even when it could be important.
1.👀 Hick's Law :
More options leads to harder decisions.
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.
2.💼 Confirmation Bias
People look for evidence that confirms what they think.
People tend to search for, interpret, prefer, and recall information in a way that reinforces their personal beliefs or hypotheses.
Previous stimuli influence users' decisions.
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.
4.🚛 Cognitive Load
The total amount of mental effort that is required to complete a task.
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.
5.⚓️ Anchoring Bias
Users rely heavily on the first piece of information they see.
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.
Subtle hints can affect users' decisions.
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.
7.🍰 Progressive Disclosure
Users are less overwhelmed if they're exposed to complex features later.
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.
8.🎯 Fitts's Law
Large and close elements are easier to interact with.
Fitts's law is a predictive model which states that the time to acquire a target is a function of the distance to and size of the target. This is mainly used to model the act of pointing, either physically (e.g., with a hand) or virtually (e.g., with a computer mouse).
9.🐠 Attentional Bias
Users' thoughts filter what they pay attention.
10.💔 Empathy Gap
People underestimate how much emotions influence user behaviors.
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11.⛵️ Visual Anchors
Elements used to guide users' eyes.
12.🌶 Von Restorff Effect
People notice items that stand out more.
The order in which people perceive what they see.
14.🔭 Selective Attention
People filter out things from their environment when in focus.
People neglect things that don't make it past a selection process.
Users tune out the stuff they get repeatedly exposed.
Users have learned to ignore content that resembles ads, is close to ads, or appears in locations traditionally dedicated to ads.
Elements that are close and similar are perceived as a single unit.
Elements that communicate what they will information.
Users' attention is drawn to higher visual weights.
20.🚨 External Trigger
When the information on what to do next is within the prompt itself.
21.🕺 Decoy Effect
Create a new option that's easy to discard.
When we are choosing between two alternatives, the addition of a third, less attractive option (the decoy) can influence our perception of the original two choices. Decoys are “asymmetrically dominated”: they are completely inferior to one option (the target) but only partially inferior to the other (the competitor). For this reason, the decoy effect is sometimes called the “asymmetric dominance effect.”
22.🎪 Centre-Stage Effect
People tend to choose the middle option in a set of items.
The way information is presented affects how users make decisions.
The framing effect happens when your decision is influenced more by how the information is presented (or worded) than by the information itself. It's partly due to the fact that people evaluate their losses and acquire insight in an asymmetric fashion
24.🍣 Law of Proximity
Elements close to each other are usually considered related.
25.🍬 Tesler's Law
If you simplify too much, you'll transfer some complexity to the users.
26.🧨 Spark Effect
Users are more likely to take action when the effort is small.
27.🥏 Feedback Loop
When users take action, feedback communicates what happened.
28.😻 Expectations Bias
People tend to be influenced by their own expectations.
People perceive designs with great aesthetics as easier to use.
When users try to give sense to information, they make stories and assumptions to fill the gaps.
30.👥 Social Proof
Users adapt their behaviors based on what others do.
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.
People value things more when they're in limited supply.
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!
32.💭 Curiosity Gap
Users have a desire to seek out the missing information.
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.
33.🖲 Mental Model
Users have a preconceived opinion of how things work.
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.
34.👨👩👧👦 Familiarity Bias
People prefer familiar experiences.
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.