From http://twistingwrists.wordpress.com/page/2/ I found an interesting study that a Professor Richard Wiseman of the University of Hertfordshire conducted. His goal was to find out why some people are lucky and some are unlucky:
I placed advertisements in national newspapers asking for people who felt consistently lucky or unlucky to contact me.
Hundreds of extraordinary men and women volunteered for my research and over the years, have been interviewed by me. I have monitored their lives and had them take part in experiments. The results reveal that although these people have almost no insight into the causes of their luck, their thoughts and behaviour are responsible for much of their good and bad fortune. Take the case of seemingly chance opportunities. Lucky people consistently encounter such opportunities, whereas unlucky people do not.
I carried out a simple experiment to discover whether this was due to differences in their ability to spot such opportunities. I gave both lucky and unlucky people a newspaper, and asked them to look through it and tell me how many photographs were inside. I had secretly placed a large message halfway through the newspaper saying: ‘Tell the experimenter you have seen this and win $50′.
This message took up half of the page and was written in type that was more than two inches high. It was staring everyone straight in the face, but the unlucky people tended to miss it and the lucky people tended to spot it.
Unlucky people are generally more tense than lucky people, and this anxiety disrupts their ability to notice the unexpected.