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Phi phenomena

  1. 1. Phi Phenomena
  2. 2. • perception – process of recognise, interpret or give meaning to the information provided by sense organs is called. • illusions - Misperceptions resulting from misinterpretation of information received by sensory organs. experienced most of us. • result from an external stimulus situation • generate the same kind of experience for all
  3. 3. • Unlike a hallucination which is a distortion in the absence of a stimulus, • an illusion describes a misinterpretation of a true sensation. • There are three clearly very different kinds of illusions: 1. Physical – • disturbance of light, • light between objects and the eyes etc. Eg .Rainbow, Doppler effect
  4. 4. 2. Physiological • the functional and structural characteristics of the sensory apparatus • as the afterimages following bright lights, • adapting stimuli of excessively longer exposure • example Hermann grid illusion and Mach bands
  5. 5. 3. Cognitive • results from misinterpretations of seemingly adequate sensory cues. • perceiver making an error in processing sensory information. • error arise within the CNS (brain and spinal cord)  result from competing sensory information  psychologically meaning ful distorting influences  previous expectations (mental set). • example Müller-Lyer illusion
  6. 6. • extremely different kinds of causes • they can produce some surprisingly similar illusions • difficulties of classification that require experimental evidence.
  7. 7. Cognitive illusion can be further classified into 1. Optical • characterised by visually perceived images that are deceptive or misleading. • Example
  8. 8. 2. Auditory • the listener hears either sounds which are not present in the stimulus, or "impossible" sounds. • Example: The MgGurk effect
  9. 9. 3. Tactile • the perception of a quality of an object through the sense of touch • does not seem to be in agreement with the physical stimulus • Example – Phantom Limb
  10. 10. 4. Temporal • is a distortion in the perception of time • occurs for various reasons, such as due to different kinds of stress. • Example chronostasis
  11. 11. 1. Induced Motion • illusion of movement that happens when a frame of reference moves in one direction and produces the illusion that a stationary object is moving in the opposite direction.
  12. 12. 2. Autokinetic Effect • a phenomenon of visual perception in which a stationary, small point of light in an otherwise dark or featureless environment appears to move. • presumed to occur because motion perception is always relative to some reference point, and in darkness or in a featureless environment there is no reference point, so the position of the single point is undefined.
  13. 13. • Alexander von Humboldt (1799 )while looking at stars with the naked eye, but thought it was a real movement of the stars. • Richard Gregory – with lack of peripheral information, eye movements which correct movements due to muscle fatigue are wrongly interpreted in the brain as movement of the perceived light.
  14. 14. 3. Stroboscopic Motion. • illusion arises when an object or picture is viewed during separate time intervals that succeed one another in a periodic manner.
  15. 15. • result of persistence of vision—the retention in the viewer’s consciousness of a perceived visual image for a short time after the picture or object producing the image disappears. • time between successive intervals when the picture or object is viewed is shorter than the visual-persistence time • the images resulting from the discrete acts of viewing are fused into a single image, and the viewer thinks he continuously sees the picture or object.
  16. 16. 1. separate pictures are viewed intermittently and the positions of the objects in each picture are slightly shifted relative to the positions in the preceding picture. Ex. motion in motion pictures and television. 2. In the second type of stroboscopic effect, an illusion of apparent lack of motion or of slowed motion occurs when a moving object periodically, takes up a previous position.
  17. 17. 4. Motion Pictures • also called film or movie • series of still photographs on film, projected in rapid succession onto a screen by means of light. • Due to persistence of vision- illusion of actual, smooth, and continuous movement.
  18. 18. • perceptual optical illusion • disembodied perception of motion is produced by a succession of still images.
  19. 19. • it is not fully understood, but it has led to significant research into visual perception. • Max Wertheimer was led to this studies of perception and the formulation of new ideas that led to the founding of the school of Gestalt psychology through his discovery of this phenomenon
  20. 20. • first described by Max Wertheimer in his 1912 paper Experimental Studies on the Perception of Motion. • he considered it to be "pure movement"— movement that does not involve perceiving the movement of any object. • claimed movement is a primary sensation • fundamental principles in the school of Gestalt psychology
  21. 21. • With phi, the circles appear stationary, but movement is perceived around them. • The color phi phenomenon - perception of motion and color change is produced by a sequence of still images of different colours.
  22. 22. • Max Wertheimer, Kurt Koffka, and Wolfgang Kohler • due to an electrical charge passing across the brain giving a sense of movement. • idea and the simple design of experimental apparatus to test it, led to significant research into visual perception. • its validity is debated
  23. 23. • GP - real and apparent movement were mediated by the same process • causes the illusion of apparent motion with phi phenomenon not understood • theories involve a physiological, rather than psychological explanation, • with the various ways the brain and optic nerves communicate.
  24. 24. Theories of Phi-Phenomenon 1. Inference Theory • Hermann Ludwig Ferdinand von Helmholtz • First, the retina is a two dimensional structure, could only indicate where an object was horizontally and vertically in the visual field; it could not be the basis for an explanation of three-dimensional visual perception. • Something had to be added to the retinal sensations, to embellish them
  25. 25. • Second, Müller’s doctrine - each sensory nerve, only gave a report specific to it. • sensory report was inadequate to represent the external world. • Often Perception is not consistent with sensory stimulation. • subsequent processing of the sensory input before it was delivered to consciousness as the completed percept. • Processing from experience and would come to serve as signs of external agents and events.
  26. 26. • According to Helmholtz, the different nerve fibers coming from the different sensory receptors provide signs about the nature of the stimulating agent • At first the perceiver is without prior experience, these sensory experiences, which will symbolize the object world, are without any objective meaning but from birth, patterns of sensory experience are being ceaselessly taken up • With accumulating experience, the mind—a physiological, or brain process—builds up a store of experiences and, as a consequence, expectations are built up. • It is upon the basis of these expectations that an imagined world of objects (not a known world) is constructed.
  27. 27. Brain Field Theory • Kurt Lewin adopted the concept of fields of force (taken from physics) to explain behaviors in terms of the importance of making meaning (i.e., whole perceptions) from social interaction. • Any interruptions in the equilibrium would result in tensions impelling conflict reductions. • the motivational force in a person to reach an environmental goal is determined by three factors  tension , or the magnitude of a need;  valence , or the properties of the goal object;  psychological distance of the person from the goal
  28. 28. • intent to complete a task or to solve a problem produces states of tension. • Goals become attractive acquire positive valence, to the extent that they can satisfy needs. • The closer a person is to the goal, the greater is the motivational force.
  29. 29. • significant role in Gestalt psychology, • it changed the way perception was studied • new ways to study the way the human brain • visual system perceive and interpret information.

Notas do Editor

  • Computerized demonstrations of phi phenomena often show a circular group of smaller circles, which switch on and off in quick sequence