Sometimes a scientific study is done that convincingly proves something that we have long considered to be likely. An example of this has just been published, showing that, other things being equal, optimists live longer than pessimists. We can supply obvious reasons for this - for instance, an increased likelihood of suicide amongst pessimists.

Between 1962 and 1965 patients attending the Mayo Clinic in Rochester, USA, for medical care were given a personality test that included questions to determine their position on an optimism-pessimism scale. The questions was designed to measure how a person habitually explains the causes of major events in life, which allowed them to be rated on a scale adjusted to 100 points. Individual expected 15-year survival was estimated from insurance tables - the average chance of surviving 15 years for the whole group was 97%.

The participants were grouped into optimistic (score of 39 or less), mixed, (score of 40 to 60) or pessimistic categories (score of 61 or over). There were 124 optimists, 518 mixed and 197 pessimists. In general, the optimists were slightly younger, and were more often men.

Thirty years later, in 1994, the workers at the Mayo Clinic determined if each of the participants was alive or dead. The analyses conducted made adjustments for the effects of different sex ratios, age and expected 15-year survival in the three groups. After these adjustments, it was found that a high score on the optimism-pessimism scale (i.e. greater pessimism) was associated with an increased death rate - a 10% increase in pessimism was associated with a 19% increase in mortality. These results were confirmed using a second type of analysis, in which survival graphs for the three types of personality were compared with those for a comparable large group of similar persons.

The authors of the study put forward various possible explanations for the results. In laboratory experiments, animals can be put in conditions of "learned hopelessness", which results in decreased immunity and a more rapid growth of tumors. In other words, hopelessness may cause decreased bodily resistance to infections or cancer. Again, optimists may be more likely to seek help if they have a medical problem, in the belief that they will be cured, whereas pessimists will be less active in looking for such help.

No doubt there are many possible explanations for the results of this study. The important questions, however, are whether it's possible to change someone's personality to be more optimistic, and, if so, would such a change be associated with an increased rate of survival? While many psychologists believe that personality is "fixed" by the age of five, others have said that it's possible to change people with aggressive or hostile behavior (once called type A personalities) into less aggressive persons. Dr. Seligman, author of "Learned Optimism", believes it is possible to change a pessimist into an optimist¹.

All that remains now is for someone to do another 30-year study to see whether people who were originally pessimists and were converted to optimism actually live longer than those who were allowed to continue in their gloomy ways. In the meantime, lets look on the bright side.