The 9 psychological phenomena in user experience design are

1. The principle of least effort. 
2. The principle of perpetual habit. 
3. The Principle of socialization. 
4. The principle of emotional contagion. 
5. The principle of identity. 
6. The Principle of beauty. 
7. The magical number seven, plus or minus two. 
8. The principle of mistakes. 
9. Focus, attention, and concentration. 

1. The principle of least Effort: 

The principle of least effort is simple and self-explanatory: people are looking for ways to complete tasks with the least possible effort. This principle applies not only to people but also to animals and even machines – the simplest algorithm is always the most attractive one.

For example, if you have two paths that would get you from one place to another place, you will choose a shorter path given that they are equally safe and comfortable. 

2. The principle of perpetual habit: 

The principle of perpetual habit states that people greatly rely on their memory and habit when doing any task. For example, if you are a frequent flyer, you know that you go to check-in first and leave your luggage, then you go through a security check, then through the customs and duty-free and then you approach the boarding gate. If for some reason, you arrived at the airport and the whole process started not with check-in but with customs, you would get confused and angry. The same applies to website and mobile app users – they want things to be where they should be.

3. The principle of socialization: 

Aristotle once said: “Man is by nature a social animal.” 

The rule still applies in the 21^st century, the era of the internet. People want to be social and they greatly rely on technology in order to achieve it. More than that, they use technology in order to feel accepted into society. 

4. The principle of emotional contagion: 

Have you ever noticed that emotions are contagious? If a person you like is laughing out loud, you will be smiling. If somebody in a very well-made movie is crying, you will feel sad. This is the psychology of UX design and of human beings – we subconsciously take over the emotions and behaviors of other people, especially of those we like. 

5. The principle of identity: 

Everyone needs a sense of identity, a feeling of belonging, and an understanding of who they are. This is why applications or websites with wallpapers are so popular – people customize their devices to feel unique. This is why people collect awards and medals – to feel appreciated and recognized. 

A similar thing happens with brands. People like associating themselves with brands because it gives them a sense of identity. “I prefer products from Google, so only Google Pixel and Google Home for me.” 

6. The principle of beauty: 

Numerous psychological studies prove: that beautiful people and beautiful things are always more loved and popular than unattractive ones. People choose books by their cover. Given the opportunity to choose, people choose beautiful places to travel to, beautiful houses to live in, and nice clothes to wear. Few people can stay away from pursuing beauty. The concept of beauty is often associated with the words expensive, successful, and high quality. 

7. The magical number seven, plus or minus two: 

The magical number seven, plus or minus two: Some limits on our capacity for processing information is a psychological article published by George A. Miller. According to this paper, a person can hold from five to nine things in their short-term memory. The “Seven Plus or Minus Two” rule is also known as Miller’s rule. 

8. The principle of mistakes: 

All people make mistakes. Mistakes spark a wide range of emotions in people’s minds, mainly negative ones – from sadness and anxiety to procrastination and apathy. Regardless of its severity, a mistake is still a mistake, and it is annoying. What are the mistakes in terms of user experience design psychology? These are counter-intuitive, unclear, or misleading scenarios, which prevent people from achieving their goals with the software. 

For example, there is an online store of eco-products I truly love, but every time I make an order, I face a certain difficulty. Once I proceed to online payment, I have to include the order number in the payment description, but this number is nowhere to be found. It is neither on the payment page nor on the check-out page – I still have no idea where to find it. As a result, I am struggling to make a purchase and looking for a different store. 

9. Focus, attention, and concentration: 

Normally, the attention span of an adult is from ten to twenty minutes. After this short time, people tend to lose focus and concentration and get distracted by their own thoughts or the things around them. The job of a UI/UX designer is to grab users’ attention and retain it for as long as needed. To do so, you have to reduce distractions and break the monotonous routine. 

To wrap up: Once again, UI/UX design is all about psychology. You design not a product – you design interaction with the user. This is why you have to know your users, their human nature, their inclinations, weaknesses, strong points, and fears. ��