Past research has found that older people are often happier with their lives than younger individuals. Some focus more on brighter memories, while others seek out situations that will raise their spirits.

Psychologist Derek M. Isaacowitz of Northeastern University and the late Fredda Blanchard-Fields of the Georgia Institute of Technology, wanted to gain more insight into why older people can be happier than younger individuals. The pair stressed the importance of more rigorous research on this topic in a recent issue of Perspectives on Psychological Science.

"There is a lot of good theory about this age difference in happiness," Isaacowitz said. "But much of the research does not provide direct evidence."

For instance, research has shown that older individuals who are shown pictures of faces and situations often focus on and remember the ones that are more positive. However, Isaacowitz wrote that seeing happier faces does not always make people feel better. In some cases, accentuating the negatives in these pictures and situations can help younger individuals feel better.

Isaacowitz wrote that further research will not make current theories obsolete, but it will make it harder for people to make generalized statements about older people being happier.

One way for people to see if their mood is brightening with age is to complete a personality test.