Extroverts are the cheeriest personality type, and a new study finds that the root of their happiness may be in their memories.

People who are extroverted remember the past in a more positive light than other personality types, researchers report in the June issue of the journal Personality and Individual Differences. This rose-tinged viewpoint explains much of the happiness gap between extroverts and people who are neurotic, a personality trait marked by anxiety and irritability.

"We found that highly extroverted people are happier with their lives because they tend to hold a positive, nostalgic view of the past and are less likely to have negative thoughts and regrets," study researcher Ryan Howell, a psychologist at San Francisco State University, said in a statement. "People high on the neurotic scale essentially have the exact opposite view of the past and are less happy as a result." [Read: Happiness Falling as Recession's Psychological Toll Continues]

Howell and his co-author asked 754 undergraduate students to complete a series of questionnaires on personality, life satisfaction and personal memories online. They found that those who were extroverted -- a personality trait defined by high energy and the tendency to seek the company of others -- were most likely to recall good things from the past and downplay the bad.

In fact, having a more positive and less negative view of the past explained 45 percent of the link between extroversion and greater life satisfaction. For neurotic types, a more negative and less positive view of the past explained half of the link between their personality type and happiness level.

It's tough to change your personality, but the find is good news for those who'd like to feel happier about life, Howell said. Savoring happy memories or recasting sad ones in an optimistic light could help, he said: "You may be able to alter your view of time and boost your happiness."

Past research has varied on whether a person's personality can change, with one study suggesting while a person may not be able to transform from a neurotic to an extrovert, we can change subtle, yet critical, aspects of personality. Another recent study suggests our personality is set by first grade.

And as is hinted in this study, personality can't explain 100 percent of our happiness. Though a complex topic, scientists are finding everything from religion to money to residence can impact happiness levels.

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