When a number of separate lights are turned on and off in quick succession this gives the impression of a single light moving from one position to another. What is the term used to describe this observation?
Motion after effects19%Autokinetic effect20%Phi phenomenon20%Induced movement20%Stroboscopic motion21%
Exam Question Jul 2014
The autokinetic effect (also referred to as autokinesis) is a phenomenon of visual perception in which a stationary, small point of light in an otherwise dark or featureless environment appears to move.
The motion after effect is a visual illusion experienced after viewing a moving visual stimulus for a time with stationary eyes, and then fixating a stationary stimulus. The stationary stimulus appears to move in the opposite direction to the original (physically moving) stimulus. The motion after effect is believed to be the result of motion adaptation.
Induced movement or induced motion is an illusion of visual perception in which a stationary or a moving object appears to move or to move differently because of other moving objects nearby in the visual field.
Stroboscopic motion is the illusion of motion that occurs when objects disappear and then quickly reappear nearby. This is the basis of film.
Gestalt psychology
Gestalt psychology developed in response to the work of Wilhelm Wundt who was the founder of structuralism. Followers of structuralism thought that the best way to understand the mind was to break thoughts down into their most basic components and then create laws regarding how they are connected.
The Gestalt psychologists recognised that individual items/thoughts need to be examined together. This was because they understood that individual items interact and add complexity to the overall picture.
Important names associated with Gestalt psychology are Max Wertheimer, Kurt Koffka, and Wolfgang Köhler.
Max Wertheimer noted that rapid sequences of perceptual events, such as rows of flashing lights, create the illusion of motion even when there is none. This is known as the phi phenomenon. Motion pictures are based upon this principle, with a series of still images appearing in rapid succession to form a seamless visual experience.
The best way to appreciate this concept is to examine the Gestalt laws of perceptual organisation
The Gestalt laws of perceptual organisation explain how we tend to organise parts into wholes. The laws are listed below.
- Pragnanz - This is the central law that states that 'every stimulus pattern is seen in such a way that the resulting structure is as simple as possible'.
- Similarity - Items that are similar tend to be grouped together.
- Proximity - Things that are near each other seem to be grouped together.
- Continuity - Points that are connected by straight or curving lines are seen in a way that follows the smoothest path.
- Closure - Things are grouped together if they seem to complete a picture. When presented with a picture we tend to fill in the gaps to turn something into a meaningful image.
