Christi Bamford, assistant professor of psychology at Jacksonville University, who led the study when she was at the University of California, Davis, and colleagues had 90 mostly white children ages 5-10 listen to six illustrated stories in which two characters feel the same emotion after experiencing something positive (getting a new puppy), negative (spilling milk), or ambiguous (meeting a new teacher).
Following each experience, one character has a separate optimistic thought, framing the event in a positive light, and the other has a separate pessimistic thought, putting the event in a negative light, Bamford said.
The researchers described the subsequent thoughts verbally, then asked the children to judge each character's emotions and provide an explanation for those emotions.
The study, published in the journal Child Development, said children as young as 5 predicted people would feel better after thinking positive thoughts than they would after thinking negative thoughts, but there was significant development in the children's understanding about the emotion-feeling link as they grew older.
"The strongest predictor of children's knowledge about the benefits of positive thinking -- besides age -- was not the child's own level of hope and optimism, but their parents'," Bamford said in a statement.