experimental psychology

1. Phi Phenomena

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. • 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. 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. 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. • extremely different kinds of causes
• they can produce some surprisingly similar
illusions
• difficulties of classification that require
experimental evidence.

7. Cognitive illusion can be further classified into
1. Optical
• characterised by visually perceived images
that are deceptive or misleading.
• Example

8. 2. Auditory
• the listener hears either sounds which are
not present in the stimulus, or "impossible"
sounds.
• Example: The MgGurk effect

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. 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. 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. 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. • 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. 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. • 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. 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. 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. • perceptual optical illusion
• disembodied perception of motion is produced
by a succession of still images.

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. • 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

23. • 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.

24. • 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

25. • 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.

26. 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

27. • 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.

28. • 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.

29. 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

31. • 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.

32. • 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.