Researchers have found evidence that babies smile for a purpose. They want others to smile in response, especially when it comes to their mother. New research on babies' smile was carried out by UC San Diego researchers.

As per the researchers, babies are as clever as comedians when it comes to bringing happiness, even when they put minimum effort to make others smile.

According to Javier Movellan, a UC San Diego psychologist who led the study, she used to get surprised when her daughter was making efforts to communicate with her when she was a baby. She said that babies are quite goal-oriented.

To conduct the study, the researchers programmed a very social 'toddler' robot named 'Diego-San' to imitate how babies smile. After that, the machine interacted with a number of undergraduate students who were enrolled for the study. Diego-San obtained many smiles, without much effort. It appeared that only students tuned out the robot when it smiled in an unnatural and random manner.

Movellan, a researcher in the university's Machine Perception Lab, said it felt as if the robot was alive.

According to the study, "The results of our analysis show that by the time infants reach four months of age both mothers and infants time their smiles in a purposeful, goal-oriented manner. Mothers consistently attempted to maximize the time spent in mutual smiling". On the other hand, infants tried to make the most of mother-only smile time, the study added.