Rotoscopy is a cinematographic technique whereby animators trace live footage to make cartoons more realistic. Invented in 1914 by Max Fleischer, the technique has been used in, for example, Star Wars and Walt Disney films and to make the title sequence of The Good, the Bad and the Ugly; it has also been used in computer games such as Prince of Persia.
A similar technique is used by Richard Linklater in his films Waking Life (2001) and A Scanner Darkly (2006). Linklater employs digital rotoscopy to switch between live action and animation to create surreal dream sequences; he is the first director to use rotoscopy to make full-length films.
Raymond Mar, a neuroscientist at the University of Toronto, has been using Linklater’s first film to investigate whether or not people attribute intentionality to the movements of cartoon characters. Previous neuroimaging studies suggest that the human brain responds differently to intentional movements than to others, probably so that we can distinguish biological movements from mechanical ones.
While subjects lay in an MRI scanner, Mar showed them live and animated versions of the same footage from Waking Life. It was found that two areas of the cortex implicated in detecting intentionality, the superior temporal sulcus and the temporal parietal junction, were more active when subjects viewed the live footage, whereas another area, the bilateral orbitofrontal cortex, was more active when they viewed the animated footage.
The bilateral orbitofrontal cortex responds to stimuli which are rewarding. Mar and his colleagues believe it was activated in their subjects because of the psychedelic nature of the animated footage they were viewing. Different patterns of brain activity might otherwise be observed because the live footage is more realistic and therefore contains more intentionality cues than the animated footage.
Mar’s study provides clues about how the brain perceives reality. We are social animals whose everday lives involve interactions with others. The theory of mind describes our ability to understand that others have beliefs and intentions. It follows that there are neural mechanisms for distinguishing between real people and fictional ones; why would the brain expend energy attributing a mind to, and trying to determine the intentions of, a fictional character? Studies have, however, shown that fictional characters can indeed be attributed with having a mind – if they are perceived to be realistic enough.
Watch the trailer for A Scanner Darkly: