When a person is left alone with their thoughts for too long and begins a cycle of Introverted Thinking (Ti) and Introverted Intuition (Ni).
For example: Tina is mad and Mark is attempting to help, to no avail. He leaves Tina alone and goes out with friends. This leaves Tina thinking about her problem and what caused it; how to fix it with the variables she is armed with; does Mark really even love her; she thinks about the last time he did this; etc. She is even more angry at this point!
See Typelogic for a short description of psychological symptoms and their symbols.
Refer to the WTF Years.