Depression

Depression is common. You'll probably deal with someone, perhaps even
yourself, who gets depressed.

Medicine often doesn't work, unfortunately.

There's some evidence that depressed people develop a rut in their
thinking.

Here's a categorization of the cognitive distortions, which is like a
set of cognitive biases, that depressed people develop and use,
consistently and wrongly: http://bit.ly/dZMijx .

One form of treatment is to train people's thinking to aboid these
forms of thinking. It works about as well as medicine.

Brad