Fi Phenomenon (Phi) Phenomenon What Is It, What Does It Mean?June 27, 2021
Phi Phenomenon is the perception of unreal motion that occurs as a result of presenting fixed objects at a certain interval and quickly.
A succession of images or points of light is perceived as a unit.
This phenomenon, which was described by Max Wertheimer in 1912, explains the perception that the frames shown in succession or the texts on the flashing light boards in the cinema are moving.
Formal development, known as Gestalt psychology, developed through a research study led in 1910 by German psychologist Max Wertheimer, the main founder of the new school. In the period when this approach emerged, studies in the field of physics supported the idea that there is a connection between the wholes emphasized by Gestalt thought.
In the summer of 1910, psychologist Max Wertheimer took a train to the Rhine Valley for a vacation. Along the way he began to reflect on the problem of visible movement. How did movement emerge from those still images? Going on the train, Wertheimer saw that the analytical approach would not yield any results. The apparent movement was not the result of parts; it came from the whole. Wertheimer later expressed this concept as a principle that forms the cornerstone of Gestalt theory: The whole is different from the sum of its parts.
Wertheimer liked the idea so much that he immediately got off the train and settled in a hotel to begin the experiments. He soon developed a series of experiments to study visible motion. The most important of Wertheimer’s experiments was that of a person sitting in a dark room staring into the dark void. The observer was unaware that there were two lights in front of him. One of the lights was on the left of the room and the other on the right. The lamp on the left came on and then went out, and twenty milliseconds later the light on the right came on and went out. The observer said that a single light came on from the left and went right before it went out. The motion the observer sensed did not really occur in the room, nor were there any atoms that could explain the effect. Movement was a fiction of the observer.
Wertheimer conducted many other experiments to measure the role played by space and time in this result. He also showed some people a light that actually burned, moved, and went out. Observers said they saw no difference between this actual movement and visible movement. In a movie, people walking on the street look just like people walking on the street in real life. But there is no movement in the input; it is an act in the mind of the observer.
Wertheimer continued his more formal research at the University of Frankfurt. There were two other young people in Frankfurt who had studied with Wertheimer at the University of Berlin a few years ago: Kurt Koffka and Wolfgang Köhler. Each of them had done productive work in psychology. After a while, they were all engaged in the struggle against Wundt’s structuralism. Wertheimer’s research problem, of which Koffka and Köhler worked as subjects, involved “Perception of Apparent Motion,” that is, motion perceived when there is no actual physical motion.
Wertheimer reflected light through two slits, one vertical and the other 20 or 30 degrees to the vertical, using an instrument (tachythoscope) that provided sequential, short-interval and rapid-paced presentation of the stimulus. If the lights were shown first through one slit and then through the other with a long gap (more than 200 milliseconds) between them, two consecutive lights appeared to the subjects, first in the first slit and then in the other. When the gap between the lights was very short, the subjects saw the lights all the time. However, when there was an optimal gap (about 60 milliseconds) between the lights, the subjects saw a single line of light going from one place to another and back again.
These findings were something that could not be explained by the structuralist understanding that reduced consciousness experiences to its sensory elements. Because apparently the perception of motion could not be explained by the sum of the individual sense elements. This event was as simple and basic as a sensation, yet different from a sensation or even a series of sensations. Wertheimer called this phenomenon the Phi Phenomenon. The accepted psychology school of the period could not explain the phi phenomenon. Wertheimer, on the other hand, made the explanation that “the apparent movement does not need explanation, it exists as it is perceived and cannot be reduced to simpler things”.
Prepared by: Sociologist Ömer YILDIRIM
Source: Omer YILDIRIM’s Personal Lecture Notes. Atatürk University Sociology Department 1st Year “Introduction to Philosophy” and 2nd, 3rd, 4th Grade “History of Philosophy” Lecture Notes (Ömer YILDIRIM); Open Education Philosophy Textbook