I studied psych in college a few years back and read about a variety of studies on how individuals with slight-moderate depression respond to certain stimuli. One of the most interesting studies (unrelated to the topic) had to deal with individuals looking into a mirror after failing a task. Individuals with >= slight depression would look themselves in the eyes, while happily ignorant individuals would avoid eye contact with themselves. They attributed this with a depressed person's desire to figure out what is wrong with themselves and internalize the failure, where as the happy people would avoid internalizing the failure.