What is the phi phenomenon? How is it produced? Why couldn’t the phi phenomenon be explained by Wundt’s psychology?
Phi phenomenon can be defined, as an optical illusion in which a series of still images is perceived to be in motion, when viewed in rapid succession. It was shown by Max Wertheimer as a simple demonstration. The experiment showed that the mind perceived a rapid sequence of discreet sensory events as motion. It was based on Wertheimer’s observation from a moving train.
The experiment involved subjecting the observers to rapidly moving beams of light. The light was projected through two slits, via a tachistoscope. One light was projected vertically, and the other 20 or 30 degrees from the vertical. When the light was shown through slits alternatively with a long time interval in between, the subjects saw two successive beams of light.
When the light was projected in the same manner, but with shorter time interval the subjects saw two light beams continuously. When the light was projected with an optimal interval in between, of about 60 milliseconds, the subjects saw a single light beam. It appeared to move back and forth from one slit to another.
Max Wertheimer’s Phi phenomenon challenged the Wundt psychology. Wundt psychology could not give any probable explanation for the phi phenomenon. Wundt psychology was based on elimentalism and apperception. It seemed to observe the working of consciousness in a structured way.
His theory revolved around finding the atoms (building blocks) of consciousness, and proceeding towards understanding the way these atoms combined to create the experience. The individual sensory elements were given importance. These atoms formed the perception.
This perception of rapidly moving beams of light as single beam in motion showed that, the perception of a stimulus can differ from the elementary stimulus. According to the Wundt psychology, the stimulus in such an event would just produce two successive lines of light.