 Third principle is the principle of identity. People need a sense of identity, belonging, and understanding of who they are. Position your product as one of a kind brand. What unique values can you offer to your users? And the final principle is the psychology of mistakes. Mistakes can evoke dreadful feeling in user experience, especially procrastination. Use user testing to predict where users make mistakes, implement confirmations with serious actions, for example, flights, hotels, booking, money transfer. Those are the four psychological principles that you can start using today.