The brains of happy people are tuned to notice and enjoy the positives in life that may pass others by, according to research that may explain why some folk seem to go about wearing rose-tinted spectacles.
Brain scans of volunteers who scored high on a standard test for happiness showed activity in regions that reinforced their happy dispositions and set them up for a "cycle of positivity", scientists said.
The positive outlook on life was not a reflection of naivety or ignorance of the world's threats and dangers, they said, but an enhanced response to positive events and the opportunities around them.
Psychologists Wil Cunningham and Tabitha Kirkland at Ohio State University uncovered the effect while scanning the brains of 38 volunteers as they looked at a series of pictures designed to evoke positive, negative or neutral feelings.
The negative images included an unhappy person sitting in a chair and someone being threatened with a gun, while positive images included a basket of kittens and a bunch of flowers. Among the neutral images were patterns and household objects.
The scientists focused on part of the brain called the amygdala, an almond-shaped region used in early processing of information about the world around us and emotional reactions to it.
The scans showed that all the volunteers' brains reacted the same way to negative and neutral images, with negative pictures causing more arousal in the amygdala than neutral ones.
But the most striking result was in the happiest volunteers, who had scored five and above on a seven-point happiness test. When they saw positive images, the activity in their amygdalas rose much higher than it did in the less happy people.
The findings were reported at the Society for Neuroscience annual meeting in Washington DC.
"People with rose-tinted glasses are more responsive to positive things in the environment. But it's not at the expense of the negatives in life. They're not seeing the positives in everything, but they see the positives where they can find them," Dr Cunningham said.
"They extract both types of meaning from the world and probably have a better life because of it."
The amygdala guides other neural processes, including attention and perception, to deal with the threats and opportunities that a person encounters. Because happy people notice and respond more strongly to joyful objects and events in the world, their increased sensitivity helps reinforce their happiness over time, Cunningham added.
