As the game progresses, the game provides a lot of useful tools, and one of the most essential abilities is the ability to read minds. This ability can tell you a lot about your followers, but first you need to unlock it.
In Cult of the Lamb, how do you unlock mind-reading?
The easiest way to keep playing is to do at least three successful runs (which the game calls crusades) and defeat the miniboss at the end of each one. This means you'll always have a new follower, so try it out anyway. After the third victory, the One Who Waits will pay you a visit before you return to camp. It'll allow you to peek into your followers' thoughts (as seen in the screenshot above).
How mind-reading works in Cult of the Lamb
Once you have this ability, interact with any follower and select the thought bubble to read their mind. It's a good way to keep an eye on new members as the game progresses. Also, consider seeing their hunger and sanitation meters as a diary.