Julia Roberts had credited 'Wonder' as a ''superhero movie''.

The 50-year-old actress portrays Isabel, the mother of August 'Auggie' Pullman (Jacob Tremblay) who has a rare genetic disorder named Treacher Collins, in the production, and the movie icon believes the drama should be placed in a different film category because of the topic it addresses, as she has hailed the child protagonist a ''hero''.

Speaking to The Sun newspaper about the movie, which is based on author RJ Palacio's 2012 book of the same name, she said: ''To me, 'Wonder' is a superhero movie because Auggie is a superhero.''

The 'Pretty Woman' star has admitted she begged directors to cast her in the film adaptation of the novel because her and her children Henry, 10, as well as twins Hazel and Phinnaeus, both 12, all ''loved'' it.

She explained: ''It stopped me in my tracks. I read it with my kids, I loved it, they loved it. I hurled myself on the mercy of the producers and said, 'Please, let me be in this movie. I want to be the mom'.

''I couldn't put the book down. It is such a powerful way of telling people how they should behave to others.

''It reminded me to find moments in every day to choose the nice approach with other people.''

The movie depicts Auggie's struggle to settle in at school after being home schooled, and having to cope with the comments and questions made about his appearance caused by the condition, which he has undergone multiple facial operations to resolve.

But Auggie is conscious of the fact he has no ears, and has been left with scars on his face from the operations, which sees him wear a toy astronaut's helmet when he is in public to avoid the stares.

Jacob has revealed to help prepare for the movie he asked children at the Sick Kids Hospital in Toronto to write to him about their experiences.

The 11-year-old actor said: ''Me and my parents found children affected from the Sick Kids Hospital in Toronto. I asked if they could send me letters about their experiences. I got back all these letters and would read them before I did my scenes.''