Biological motion is a term used to describe the visual interpretation of movement. It is mostly used by those in the cognitive studies fields to describe how human beings interpret the movement of another organism. Most studies done in regard to biological motion are performed using images of only a few illuminated dots that are shown in movement, referred to as a point light display, and the subsequent responses and interpretations made by those observing the images.
The study of biological motion is mostly done by cognitive and social neuroscientists. Their purpose in studying it is to see how human beings use the visual field to interpret and extrapolate data from motion. Studies based on the interpretations made by observers of bodies in motion use limited imagery to create the picture, allowing for a wide variety of characteristics to be determined about an image based primarily on the way or speed at which the bodies in motion move.
One famous example of a study done about biological motion was published in 1973 by Gunnar Johansen. Mr. Johansen attached small sources of light to the major joint areas of subjects and then filmed them walking in the dark. The images produced several points of light against a dark background. Despite the minimal amount of data, observers who watched the film of the bodies in motion reported seeing very distinct images of human beings.
Further studies that have been done on biological motion have shown that it is possible to gather other facts than just movement from limited data. According to a study done in 1994 by Mather and Murdoch, human beings can tell what gender the person is from point light displays. Other studies using point light displays have shown what mood the person being observed is in as well, as what they are doing. It has even been shown that mammals other than humans can perceive similar data. In 1982, Fox and McDaniel found that babies as young as three months can interpret biological motion.
There is conflicting data on what the value of biological motion is for clinical purposes, and some have stated that the sensors used to interpret the data are not as specialized as once thought. Two areas of the brain have, however, been found to be involved in the perception of biological motion. The pre-motor cortex is reportedly involved in the process of creating the links between the dots in point light displays, and the superior temporal locus has been found to be activated during the time perception takes place. These findings can help us understand how the brain works and could potentially be used as a diagnostic tool.