I am not sure exactly how it works, but this is amazingly accurate. Read the full description before looking at the picture.
The picture below has 2 identical dolphins in it. It was used in a case study on stress level at St. Brenda's Hospital.
Look at both dolphins jumping out of the water. The dolphins are identical.
A closely monitored, scientific study of a group revealed that in spite of the fact that the dolphins are identical, a person under stress would find differences in the two dolphins. If there are many differences found between both dolphins, it means that the person is experiencing a great amount of stress.
Look at the photograph and if you find more than one or two differences, you may want to take a vacation.