Having an imaginary friend as a child boosts language development and may enhance academic performance, according to new research.

In a study in the latest issue of the journal Child Development, Otago University associate professor Elaine Reese, and former student Gabriel Trionfi, of Clark University in the United States, investigated the language skills of 48 boys and girls aged 5-1/2, of whom 23 had imaginary friends.

They found that the 13 girls and 10 boys who had engaged in imaginary companion play had more advanced narrative skills than children who had not.

"Because children's storytelling skills are a strong predictor of their later reading skill, these differences may even have positive spinoffs for children's academic performance," Prof Reese said.

The researchers assessed the children's language skills in several ways, including measuring their vocabulary and storytelling skills.

Children with imaginary friends included more dialogue in their fictional stories, and more information about time and place in realistic stories.