An almost perfect Christmas film for the entire family, and one that I expect (and hope) will be trotted out for viewing year after year for decades to come. The theater where I watched it was about half parents/grandparents and half children. Toss up as to which age group appeared to be enjoying it the most. Most children appear to find it magical, and any adult with even an ounce of sentimentality should feel nostalgic tugs on the heartstrings based on memories of early childhood innocence.
Several adults I have talked with have commented on the unusual emotional responses they had to the appearance of the animated characters. The reasons for this have to do with the technical aspects of how this animated movie was constructed. The movie made use of “point light display” technology to tap into a perceptual phenomenon called “biological motion”. I cover some of the technical aspects of biological motion perception in my book (Ronald G. Boothe, Perception of the Visual Environment, Springer-Verlag Publishing Company, 2002).
Point light displays are used by experimental psychologists to study perception. Small lights are attached to the body of a human at particular locations (typically to the feet, knees, hips, shoulders, elbows, hands, and head). Then the human is filmed while performing some action such as walking or running. Finally the film is shown under low contrast conditions such that nothing can be seen except the lights. Keep in mind that what is displayed on the screen is nothing except small lights moving. However, someone looking at these displays immediately perceives that what is being shown is a human engaged in walking, running, or whatever activity was being filmed. Furthermore, the human observer can often make rather remarkable judgments about other aspects of what was being filmed. For example, whether the person being filmed was male or female, in an agitated or tranquil state of mind, etc.
Motion of the spots is required. If the individual being filmed stands perfectly still so that nothing is displayed on the screen except stationary spots of light, then nothing is perceived except stationary spots of light. Furthermore, not just any old motion will do. Motion that shows up on the screen when viewing films of point light displays is constrained by the anatomical construction of the body. Only motion of spots that is consistent with these anatomical constraints gives rise to perception of biological motion. Spots of light that move in ways that would not be physically possible for the anatomical body are perceived simply as moving spots of light rather than as biological motion.
The phenomenon of biological motion perception has allowed experimental psychologists to discover some important properties about how our brains process information from the eyes in constructing our percepts. Our brains do not function as a general-purpose computer. Instead, our brains have neural circuits that are specialized for looking for patterns of input that have special biological significance. The brains of primates, including humans, have evolved over millions of years to be especially sensitive to social behavior of other individuals. We constantly “read minds” in the sense of inferring the intentions and mental and emotional states of the individuals around us. We are able to sense that an individual with whom we are talking is getting bored or angry based on extremely subtle cues such as a change in body posture. The reason we are able to do this so efficiently is because the parts of our brain that process perceptual information are designed to be exquisitely sensitive to patterns of input that signal these mental states.
In the ordinary world, it is perception of other humans that triggers biological motion perception. Inanimate objects such as cartoon figures do not. In Polar Express, the filmmakers filmed human actors while they were wearing point light displays. Then the motion of the point lights was used to constrain the motions of the cartoon characters that were constructed during the animation process. That is the reason the animated characters are able to trigger such powerful emotional reactions in the audience. The movements of cartoon characters are suddenly activating the specialized neural circuits in our brains that under ordinary conditions are only activated by events such as posture adjustments in other humans. These neural circuits in the perceptual processing portions of our brains feed into other parts of our brain that are used for perceiving, and reacting to, the mental and emotional states of other humans.
Biological motion perception is an important, but not the only, specialized neural processing mechanism that enables us to infer the mental and emotional states of other individuals. Another set of specialized neural circuits are involved in processing faces. Ordinarily, the neural circuits involved in biological motion perception and in face perception work in concordance. However, in Polar Express, the faces of the cartoon characters were not designed to trigger the special face perception neural circuits. This leads to a disconnect in our brain while watching the movie because some parts of the brain (biological motion processing circuits) are reacting to the cartoon characters as though they are truly human like, while other parts of the brain (face perception circuits) are reacting to the cartoon characters as though they are inanimate.
This disconnect accounts for the fact that many people watching this movie report that the characters seemed unnatural, perhaps even “spooky”. Some critics have labeled this as a negative aspect of the movie, arguing that the cartoon characters do not appear realistic. Personally, I think this criticism is misguided and misses the point of the movie. Polar Express is not meant to be “realistic”. Instead, it evokes an emotionally powerful ‘dreamlike’ experience of early childhood memories of Christmas. Memories that all of us have, at least in our subconscious, of a time of innocence, when Christmas was still magical – before the childhood experience becomes replaced by the jaded realities of dashed hopes, shattered dreams, disillusionment, and crass commercialization.
I gave this movie a rating of 5 stars
Ron Boothe