15 User Experience Principles and Theories

12 min readApr 27, 2021

User Experience Principles to improve your designs

Have you ever wondered how a perfect design is created? Do you ever go through a website that is very appealing to you and think about how he/she designed it? Designing is a very broad area with many features and aspects. But whatever you do, there is a set of principles that can be followed to give the user the best experience they can get.

These principles will help you to create an amazing design that is convenient for you and the user both. This set of guidelines will make your job as a designer much easier to follow. There are many principles out there for UX Design, but today I will discuss some basic and important laws that will be very useful to a designer.

1. Aesthetic Usability Effect

A minimalistic and aesthetic design is appealing for a user. When you have a pleasing design, users tend to tolerate minor usability issues and make the product more usable for the user. Such a design can also provide positive feedback for a user that they will believe the design actually works better. When the user is given the best user experience which is visually appealing, the user would want to keep coming back to use the feature more and more.

For example, the search engine, Google is very minimalistic. It has all the necessary information displayed for the user and the key usage of it is visible at a glance. As a User Interface, Google does not mislead the user with unnecessary information and it showcases all the important features and functions in the most minimalistic way.

2. Doherty Threshold

When the user and the interface he/she interacts with, moves at a pace in which both parties do not have to wait for the other, productivity increases. It is stated by Walter J. Doherty that a system must provide its feedback within 0.4 seconds (400ms) or less to the user. A system must have a fast responsive method. Then the user will not be frustrated, time is not wasted and productivity increases.

For example, on a Sign-in page, the ‘Forgot Password’ option deals with the user at a very high speed. When the user clicks the ‘Forgot Password’ option, he will be redirected to select a Password recovery option; by email or phone number. When the user clicks on his desired option, he will receive a verification code within 0.4 seconds or less to reset his password.

Source: The Economic Value of Rapid Response Time research paper by Walter J. Doherty, published by Jim Elliott

3. Fitt’s Law

This law states how the time needed for a user to reach the target depends on the distance to the target and the size of the target. If the target size is smaller and has a longer distance, the user will take more time to reach the target. It is good practice to have whitespace in between the targets too.

For example, if the buttons are too small the user will not be able to interact with the application properly. He will have to take more time than usual to click the button as the distance to reach the button is long. Also, there is not enough white space within the buttons therefore the user might click on the wrong button if he is in a hurry.
But, if the buttons are located perfectly with a definite amount of white space in between the buttons, the user will not mistakenly click on the wrong button either. Furthermore, the user will reach the button in a shorter time because of the larger button size.

Source: Fitts’s Law: The Importance of Size and Distance in UI Design by Interaction Design Foundation

4. Miller’s Law

According to studies done by George A. Miller, it was found that any average person can only keep 7 (+/- 2) elements in his/her short-term memory. When displaying information on a website or an app, put those items into groups of 5–9 and this would improve the ability for a user to take in information and make a decision.

For example, if there is a menu with alot of options, it will be hard for the user to select one because there are a lot of options that he should consider.
If these options are divided into 4 groups according to their similarities, it will be easier for the user to select which option he/she needs according to the respective group.

Source: George A. Miller by Marie Doorey

5. Zeigarnik Effect

It has been found that users tend to remember uncompleted tasks more than completed tasks. According to Abhishek Chakraborty’s article, our brain usually tricks us, or rather we trick our brain into remembering only those things which are incomplete. You can use progress bars for complex tasks to let the user know when he/she has an incomplete task. This can be used to increase the chances of the user completing all the required tasks.

For example, this law can be seen on Websites such as LinkedIn or Grammarly where you will be given a progress bar to see how much your profile is complete. The user will be persuaded to complete the progress bar by completing all the necessary tasks needed.

Source: The Zeigarnik Effect: Why it is so hard to leave things incomplete by Abhishek Chakraborty

6. Hick’s Law

If the choices that the user has are complex, the time taken for the user to make a decision is much higher. Having simple choices and breaking down complex choices into simpler choices is the best way to resolve this.

For example, the user will be confused as to what option must be selected to checkout or to select a payment method if the given options are very complicated and messy.
If you can provide the necessary options only for the required page to simplify the checkout process so the user will not be overwhelmed.

Source: Design principle: Hick’s Law — quick decision making by Anton Nikolov

7. Postel’s Law

This law is also known as the ‘Robustness principle’. When a system is provided with input from the user, it must be able to accept input from any range. In addition to this, when you are giving feedback to the user, the message must be specific and to the point. For any number of actions the user takes, you must be flexible, responsive, and open-minded.

This principle can be understood using a form. When the user must fill the address section of a form, they might use abbreviations instead of the full name of the state or country. The form must be able to take in this information from both these formats.

Source: Robustness and least power by Steven Garrity

8. Pareto Principle

This principle states that 20% of the features of any website or application will be responsible for 80% of the results. Therefore, make sure to narrow down the important choices and features for a design to 20% of the entire website or application as this could cause a very large effect.

This 80/20 principle can be used for a simple drop down menu of choosing the country from a list of countries. This principle can be seen on Amazon. They have put ‘United States’ as the default country as most of their customers are from the United States. This saves time for any customer who is from the United States because they don’t have to go through the entire list to select the country. This is one example on how the Pareto Principle can be used.

Source: The 80/20 Rule in User Experience by Arin Bhowmick

9. Peak-end rule

People judge an experience highly based on how they felt at its peak and the end rather than based on the total or average of every moment they went through in the experience. When you are designing an application, identify moments that are most valuable and entertaining, and design those to give the user the best experience.

Before designing, you can conduct a User Research on the idea of the design and note down what moments which will be memorable for the users. These research results can tell you what peak moments you must work on and give the users the best experience.

Source: The Peak–End Rule: How Impressions Become Memories by Lexie Kane

10. Parkinson’s Law

This law specifies that when all of the available time is consumed, every task would expand. In a real-life situation, if we are faced with less time for a task, we try to finish the most important tasks at first. For example, if you’re writing an exam and you have a little time left, you would finish the most important questions you can do at first. Like so, in Parkinson’s law, if a user is given less time, he/she will feel pressured and try to finish up the important tasks to finish the task on time.

For example, consider a situation where the user is shopping online. In the checkout process, you must give the user a decent amount of time. You might have come across situations where your product will be on hold only for 5 minutes until you buy it.
These types of situations can be pressurizing for the user. To complete the entire checkout process and also give the user some time to be sure if he/she definitely wants to buy the products, you must give the user at least 15 minutes.

Source: Parkinson’s Law: Why Constraints Are The Best Thing You Can Work With by Louis Chew

11. Jakob’s Law

This law was stated by Jakob Nielsen and it says that users prefer all the platforms they use (applications, websites, products) to have the same functionalities and structures as all the other sites they already know. Making the design predictable for the user is an advantageous point to increase the user experience of your platform.

In addition to this, you can use breadcrumbs/step indicators to help the user to know where he stands in the process on the website. For Example, in an instance like completing a purchase, you can help the user by showing each step he has completed and the steps he has left to do.

For example, the ‘Sign-in’ Page for all websites and applications are the same. It is predictable for the user that you have to enter your email/username and your password when you need to sign in.

Source: Jakob Nielson: Biography by Nielsen Norman Group, Jakob’s Law of Internet User Experience by Jakob Nielson

12. Occam’s Razor

This law is also called the ‘Law of Parsimony’ and it is mainly a problem-solving principle. This law states that elements should not be multiplied without necessity as this increases the complexity to process information. It is a known fact that if there are 2 explanations for something, the explanation that has the least speculation is usually the correct one.

“Good design is as little design as possible”. — Dieter Rams

This principle can be used as a guide in designing to avoid complex user interfaces. When you are faced with 2 decisions, avoid the complex choice to ensure that a user interface is designed in the most simple manner possible. You can introduce complexity when it is necessary only.

For example, if you come across a very complicated website that has a lot of options and information on it, you would get confused and frustrated on what to do.
But if you come across a simple and minimalistic website which displays information in a simple manner, you would not be confused at all.

Source: Designing with Occam’s Razor by Jon Yablonski

13. Tesler’s Law

This law is also known as ‘Conservation of Complexity’. It states that for any system, there is a level of complexity that cannot be reduced.

As a designer, even you would like to have a smooth and simple design process that can be followed. But as we all know, even you must have faced with some level of complexity in a design process. Larry Tesler who introduced this law mentions that there will still be a level of complexity that we cannot avoid.

For example, if the user is booking a flight, he/she will have to mention a lot of information and it is a little complicated. But this cannot be avoided as they are all important information needed for the user to book the specific flight.

Source: Controls are Choices by Dan Saffer

14. Serial Position effect

This is also known as the ‘Primary and Recency Effect’. According to studies, it has been found that users tend to remember the first and the last items in a section. This law can be used and the most important items can be placed at the start and the end of a group to increase the chances of them being remembered by the user. You can also place key actions on the far left and right of a mobile application such as navigation.

For example, this law can be seen when a person checks his To-do List. You are more used to going through the first few items and the last few items on the list rather than going through everything.

Source: Serial Position Effect by Dr. Saul McLeod

15. Von Restorff Effect

This is also known as the ‘Isolation Effect’ and was introduced by the German Psychiatrist Hedwig Von Restorff. When a different element among multiple similar elements is present, the user is most likely to remember that one different element. In addition to this, this differentiated element is highly likely to get more attention when compared with the other elements. This law can be used to attract users by emphasizing specific information. But you shouldn’t overuse this law either. If you display too many differentiated elements on one page, the user can get distracted.

For example, this law can be used to display the most recommended and used plans. When the user sees one plan differentiated from the rest, he/she will be persuaded to sign up for that plan. You can see this Law being used on websites such as WordPress or Netflix.

Source: Von Restorff Effect by Coglode Research

These principles can help your design be more visually appealing and accessible to the user. It is always good practice to use these principles as a guideline to ensure that you’re creating a design that will increase user experience.