Andy Serkis found it difficult to separate being a human and a monkey while filming scenes in Vancouver for 'Rise of the Planet of the Apes'.
The British star - who, through the use of motion capture technology, became ape Ceaser in the new action adventure movie - admits he found it difficult to stop pretending to be a chimpanzee once he had stopped filming and one time found himself running in a primate fashion.
He said: "It did slip into ever day life. When we were filming in Vancouver, Canada, I used to run around Stanley Park.
"I would start off as myself but then star getting into character a bit, spending the route back as Caesar, on all fours, then on two feet."
However Andy - who has used motion capture in films including 'The Hobbit', where he played Gollum and 'King Kong' as the titular beast - loves utilising the technology because it means he can be more "subtle" than is possible when wearing a full outfit.
He told The Sun: "Performance capture is wonderful. It allows you to do it without the suit and prosthetic make-up. It allows you to play more subtly. We want there to always be the sense of the animal and the human."