Event Perception: Motor Theory vs. Direct Perception Theory

People observe lots of events around the environment and we can easily recognize the nature of an event from the resulting optic flow. The questions are how do people recognize events and what is the information in the optic flow that enables observers to recognize events. There have been debates between motor theorists and direct perception theorists regarding of these problems. Motor theorists claim that human observers exhibit special sensitivity when perceiving speech or biological motion, because we both produce and perceive those events. However, direct perception theorists suggested that speech or biological motion is not special from the perception of all other kinds of event. In this article, I review this controversy to critique the motor theory and to describe a direct realist approach to event perception. In everyday life, we observe lots of events around us, such as a person walking, a ball bouncing, water falling, etc. There is no problem for us to recognize the nature of an event from the resulting optic flow. Researchers have been investigating the questions of how people recognize events and what information is in the optic flow that enables observers to recognize events. Bingham (1995) suggested that events could be characterized in terms of dynamics. The perceptual information is projected from kinematics or motions in an event. Kinematic specification of dynamics (KSD) was formulated as a principle to be used to guide investigations of perceptual information and suggested that dynamics enables a kinematic pattern to specify events (Runeson, 1977; Runeson & Frykholm, 1983). 1 Dankook University, Requests for reprints should be sent to Young-Lim Lee, Psychology department, Dankook University, 119 Dandae-ro, Dongnam-gu, Cheonan-si, Chungnam, South Korea. * This work was supported by a grant from Dankook University (No. 122366). 18 Journal of Psychology and Behavioral Science, Vol. 2(3 & 4), December 2014 For example, in terms of dynamics, walking can be understood as an upright and inverted pendulum, while running can be understood as a bouncing ball (Alexander, 1992). There have been debates between motor theorists and direct perception theorists. According to motor theorists, speech and biological motion are different from other events because humans both produce and perceive those events. As a result, motor theorists claim that human observers exhibit special sensitivity when perceiving speech or biological motion. However, Fowler (1986, 1989) critiqued the motor theory of speech perception and suggested that speech perception is not special. Instead, she advocated a direct realist approach to the perception of speech. In recent papers, researchers in visual event perception have argued for a motor theory of biological motor perception. The problem with this approach is that it divorces biological event perception from the perception of all other kinds of events. In this article, I review this controversy to critique the motor theory and to describe a direct realist approach to event perception. I. What is Event Perception? Johansson vs. Gibson What makes events distinguished from other physical properties, such as 3D structure, is that they are spatio-temporal (Warren & Shaw, 1985). One of the prominent examples of event perception is point-light walkers in Johansson’s study (1973). Small lights were attached to the main joints of an actor dressed in dark clothes, thus only several small lights were seen in the displays. In the static displays, only a jumble was seen, but in the changing displays, a motion pattern such as walking or running was recognized. Whenever the changing displays were stopped, a jumble was seen again. Besides Johansson, Gibson is another dominant event perception theorist. Although Johansson is a motor theorist, Gibson is a direct perception theorist. Mace (1985) pointed out the salient differences between the two positions. First, Johansson and Gibson had different viewpoints on events whose changes are slow or fast. Johansson (1970) distinguished perceptible events from nonperceptible events. He said that humans do not perceive slow motion such as ripening of fruits or the fast motion of a raster which generates a static TV image. Those events change so slow or fast that they are not sufficient to be perceived and recognized.