What is something about human psychology that almost nobody knows?

 There are many aspects of human psychology that are still not fully understood or are not commonly known. Here are a few examples:

1. The "mere exposure effect": This is the phenomenon where people tend to develop a preference for things simply because they are familiar with them. In other words, the more we are exposed to something, the more we tend to like it, even if we don't consciously realize it.

2. The "illusion of transparency": This is the tendency for people to overestimate how much their inner thoughts and feelings are apparent to others. For example, when we feel nervous or anxious, we may assume that other people can tell, even if they actually can't.

3. The "hedonic treadmill": This refers to the idea that people's happiness levels tend to return to a baseline level, even after experiencing positive or negative life events. In other words, we may experience a brief boost in happiness after achieving something or receiving good news, but eventually, we return to our usual level of happiness.

These are just a few examples of the many interesting and lesser-known aspects of human psychology.