Biological motion

Biological motion is motion that comes from actions of a biological organism. Humans and animals are able to understand those actions through experience, identification, and higher level neural processing. Humans use biological motion to identify and understand familiar actions, which is involved in the neural processes for empathy, communication, and understanding other's intentions. The neural network for biological motion is highly sensitive to the observer's prior experience with the action's biological motions, allowing for embodied learning. This is related to a research field that is broadly known as embodied cognitive science, along with research on mirror neurons. Biological motion is motion that comes from actions of a biological organism. Humans and animals are able to understand those actions through experience, identification, and higher level neural processing. Humans use biological motion to identify and understand familiar actions, which is involved in the neural processes for empathy, communication, and understanding other's intentions. The neural network for biological motion is highly sensitive to the observer's prior experience with the action's biological motions, allowing for embodied learning. This is related to a research field that is broadly known as embodied cognitive science, along with research on mirror neurons. For instance, a well known example of sensitiveness to a specific type of biological motion is expert dancers observing others dancing. Compared to people who do not know how to dance, expert dancers show more sensitiveness to the biological motion from the dance style of their expertise. The same expert dancer would also show similar but less sensitiveness to dance styles outside of their expertise. The differences in perception of dance motions suggests that the ability to perceive and understand biological motion is strongly influenced by the observer's experience with the action. A similar expertise effect has been observed in different types of action, such as music making, language, scientific thinking, basketball, and walking. The phenomenon of human sensitivity to biological motion was first documented by Swedish perceptual psychologist, Gunnar Johansson, in 1973. He is best known for his experiments that uses point light display (PLD) stimulus. With PLD, Gunnar cleverly showed only the motion of the body through attachment of white dots, through light bulbs attached to body parts and joints. He then recorded actors performing various actions in the dark, removing the visual information of the body by only showing the motion of white dots against a black background. His findings showed that human participants are able to recognize what the actors are doing through motion, however the participants were unable to recognize which actions were being performed when the PLD were static. He went on to conduct several studies, along with other researchers developing their own studies. The PLD methods that he developed are still in widespread use by researchers today. Interest in biological motion was renewed with the publication of a 1996 article on mirror neurons. Mirror neurons were found to be active when actions with goals were observed, and also when the observer performs the same action themselves. The mirror neurons were initially observed in the premotor cortex, however they were also found in supramarginal gyrus and temporoparietal junction, areas of the brain that is associated with biological motion processing. The coding of both visual and motor actions within same set of neurons suggests that biological motion understanding and perception is influenced by not only the visual information of the motion but also by the observer's experience with the biological motion. Today, the discovery of mirror neurons has led to an explosion of research on biological motion and action perception and understanding in research fields such as social and affective neuroscience, language, action, motion capture technology, and artificial intelligence such as androids and virtual embodied agents, and the uncanny valley phenomenon. Findings from research on biological motion has shown that humans are highly sensitive to biological motions of actions and those observations has developed into studies on different possible factors in the perception and understanding of the biological motions of bodily actions. Through studies with point-light display (PLD), findings in psychology and neuroscience fields has grown into a sizable body of research that stretches across different fields. In a PLD experiment, participants are presented with a static, dynamic, or randomized dynamic white dots that consists of light sources or motion capture markers that were placed on the joints that are involved in actions for biological organisms. Even though individual dots in PLD do not show any overt visual connection with other dots, observers are able to perceive cohesive biological motion of actions in dynamic PLD. Studies using PLD methods have found that people are better at identifying PLD of their own gaits compared to others. People are also able to recognize different emotions in PLD. With special attention to body language, an observer can identify anger, sadness, and happiness. Observers can also identify the actors' gender with some actions in PLD. In a large study with stroke patients, significant regions that was found to be associated with deficient biological motion perception include the superior temporal sulcus and premotor cortex. The cerebellum also is involved in biological motion processing. A recent study on a patient with developmental agnosia, an impairment in recognizing objects, found that the ability to recognize the form of biological organisms through biological motion remains intact, despite deficiency in perception of non-biological form through motion.