From Feeling Good: The New Mood Therapy by David Burns
When I was eleven years old, I bought a deck of trick cards at the Arizona State Fair called the Svengali Deck. You may have seen this simple but impressive illusion yourself. I show the deck to you--every card is different. You choose a card at random. Let's assume you pick the Jack of Spades. Without telling me what card it is, you replace it in the deck. Now I exclaim, "Svengali!" As I turn the deck over, every card has turned into the Jack of Spades.
When you overgeneralize, this is performing the mental equivalent of Svengali. You arbitrarily conclude that one thing that happened to you once will occur over and over again, will multiply like the Jack of Spades. Since what happened is invariably unpleasant, you feel upset.
A depressed salesman noticed bird dung on his car window and though, "That's just my luck. The birds are always crapping on my window!" This is a perfect example of overgeneralization. When I asked him about this experience, he admitted that in twenty years of traveling, he could not remember another time when he found bird dung on his car window.
The pain of rejection is generated almost entirely from overgeneralization. In its absence, a personal affront is temporarily disappointing but cannot be seriously disturbing. A shy young man mustered up his courage to ask a girl for a date. When she politely declined because of a previous engagement, he said to himself, "I'm never going to get a date. No girl would ever want a date with me. I'll be lonely and miserable all my life." In his distorted cognitions, he concluded that because she turned him down once, she would always do so, and that since all women have 100 percent identical tastes, he would be endlessly and repeatedly rejected by any eligible woman on the face of the earth. Svengali!
My son does this. When he's upset with something that happened, he claims "this always happens to me!" It isn't true, but it is his perception. It's a little tricky to validate his feelings of frustration while pointing out that his claim of it always happening isn't reality, but perception. I'd probably have an easier time of it if I hadn't taught him to think that way in the first place. :(