PERCEPTION

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PERCEPTION
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MEANING

• Perception is a process of interpreting senses
  i.e. making them meaningful.
• Its actually a process of nervous system which
  cannot be observed directly but can only be
  experienced.
• It is the immediate activation of sensation
  resulting from the stimulus and is structured and
  organized in nature.

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PERCEPTION OF FORM

• Almost always we perceive parts of varying
  sensuous mass as different forms, shapes and
  patterns.
• Perception is converting sensation into awareness
  of objects.
• One of basic dynamisms of visual perception
  consists of our organizing tendency to see well
  defined parts of our environment as objects
  distinct from their surround.
• A contour separates the object from ground.

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PHENOMENAL PROPERTIES OF FIGURE AND BACKGROUND

• Characteristics of figure and background.
• Figures are seen as bounded and organized.
• Figures are also more striking and seem to stand
  out from their background rather than unorganized
  background.
• A figure stands in front of the background which
  extends behind it, in an unbroken manner.

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• 4. Figure is more lively, actually it is the
  carrier of movement. Even in the case of apparent
  movement, what is figural is also the conveyer of
  motion.
• 5. Figure shares the character of while
  background is like a substance or informed
  material.
• 6. Figure is always better attended to and is
  more likely to suggest meaning and excites deep
  feelings.
• 7. Relatively to background figure is also better
  remembered.

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• Rubin (1915, 21) also mentioned similar type of
  characteristics of figure and background. These
  are
• Figure has shape while background is always
  formless.
• Figure has always some characteristics of frm
  while background cannot be described in terms of
  some characteristics.
• Figure is perceived in front while background is
  perceived the figure extending continuously.
• Figure is more impressive and so better
  remembered.

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DETERMINANTS OF FIGURE AND BACKGROUND

• Gestalt psychologists like Werthiemer and Koffka
  conducted various studies to explain that
  perception is organized.
• He propounded some laws of perceptual
  organization.

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LAWS OF PERCEPTUAL ORGANIZATION

• Law of Proximity-Things that are near each other
  readily form units tending to be grouped
  together. Nearness may be in space or time e.g.

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• Similarity A number of separate items of
  several different types. such items which
  resemble one other in some respect constitutes a
  group or unit by itself. Things may resemble each
  other in many different quantitative and
  qualitative ways e.g. colour, form intensity etc.
• Common Fate Things which move simultaneously in
  same direction are readily seen as a group. They
  possess a sort of similarity in their motion.

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• Continuity The group of thing forms a uniform
  direction in some respect.
• Area As a closed region is made smaller it
  tends more strongly to be seen as a figure. A
  factor that is obviously closely related to
  proximity.
• Orientation In some kind of pattern alignment
  with the main areas of space seems to be
  determining factor. Thus, Rubin (1921) found that
  cross made up of vertical and horizontal lines is
  more likely to be seen as figure than one with
  oblique limbs.

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• Symmetry the more symmetrical is the shape the
  more strongly it itends to be seen as a figure.
• Closure The regions that are marked off by
  close contours tend to be seen as figure more
  than do those with open or incomplete contours
  e.g.

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• Homogeneity or Simplicity The areas which are
  homogenous in nature are seen as figure.
• Conformity with the observers set Einstellung
  is a German word that means directed readiness
  for a particular perceptual event. Werthiemer
  distinguished two kinds of einstellung
• Subjective to see a certain grouping and to do so
  even though the law of organization do not favour
  that grouping or even if they oppose it
  objectively. Einstellung means physical
  perseveration i.e. the tendency to continue
  seeing the given figural organization even after
  the conditions no longer favour it.

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• Experience Subjective or organismic conditions
  like past experiences influences the process of
  formation of perceptual grouping or perception
  units.

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CHARACTERISTICS OF OBJECTS WHICH DETERMINE FORM
AND SHAPE

• Contours Imagined boundaries that are used by
  subjects to separate shape from rest of the
  field.
• Edges They are an angular boundaries that are
  used to organize different perceptual properties
  of objects for perception of form.
• Figure It is an organised part of environment
  first studied by Rubin.
• Boundaries Lines which separate one object from
  the other object.

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PERCEPTION OF SPACE

• Space refers to a domain or a field in which the
  individual is situated and within it he/she moves
  about . In space we study depth, distance and
  location.
• Depth relative difference between two objects .
• Retina gets the image of the object through
  focusing in lens. Image on retina is received in
  terms of all the characteristics of space.
• This image on retina is not the true copy of
  objects but it is the careful combination of
  different characteristics of objects.

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• There are three dimensions in the space .
• Third dimension is percieved by the brain
  automatically by using some cues.
• Brain uses two types of cues.
• Cues of distance
• 2. Cues of depth.

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CUES

• Cues are nothing but characteristics of the
  stimulus variables which make it possible to
  perceive the distance between distance and depth.
• The perceiver is not aware regarding the cues.
• Importance of cues was first studied by Leonardo
  da Vinci

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CUES OF DEPTH

• These cues may be related with stimulus
  characteristics of eye and with both or single
  eye.
• NON VISUAL CUES
• Convergence It is the bending of the eyes
  towards the nose while perceiving the object. It
  is determined by cillary muscles which control
  the movement of lens. More the convergence more
  the stress. It is utilized just to get the image
  of object on fovea of retina. Convergence is
  possible up to a limit and it is tmeasured in
  terms of angular degrees.

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• 2. ACCOMODATION It refers to the frequency or
  focusing of the lens to get the image on fovea.
  As the camera focuses the lens as per distance of
  the object to get clearest images. Similarly the
  eye focus the lens as per distance of object the
  size of lens are controlled by cilliary muscles
  where convergence stops. Accommodation starts and
  it operates up to 180 feets.

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BINOCULAR CUES

• When the images are formed in both the eyes on
  their respective foveas, then these areas are
  known as corresponding areas.
• When the images are not on fovea then it is known
  as non- corresponding areas.
• When there is some disparity in corresponding and
  non- corresponding areas then these messages go
  straight to brain and brain uses some cues.

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• DOUBLE IMAGES-
• Except fixated object the images of other objects
  are not in fovea. When all the objects are in
  same direction the information of double image of
  other objects goes to the brain where it is
  analysed and used as a cue of depth perception.

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BINOCULAR DISPARITY

• As our eyes are separated by a few inches, they
  were objects from slightly different angles.
• This difference in angle causes a slight
  difference in the retinal images called retinal
  disparity.
• Although small, it is a powerful cue for depth.
• The value of this cue or a device for viewing two
  slightly different pictures.
• One with one eye and the other with other eye.

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MONOCULAR CUES

• A number of spatial cues require only a single
  eye for their reception and are labeled as
  monocular cues.
• INTERPOSITION- It refers to the appearance of one
  object partially concealing or overlapping other.
  If one object is partially covered by another the
  fully exposed is perceived as nearer.

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• 2. SIZE If a person knows the real size of a
  visible object and know the size of the retinal
  image it subtends at the eye. We have a good
  potential indication of its distance.
• 3. RELATIVE SIZE- This cue applies when two
  similar or identical shapes of different sizes
  are viewed simultaneously or in close succession,
  in such cases larger stimulus generally will
  appear closer to the viewerthan the smaller one.

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• 4.FAMILIAR OR ASSUMED SIZE- If a person know the
  objects real or distal size and we can register
  its proximal or retinal size then a person can
  till what his absolute distance is. This cue is
  particularly important to the space perception
  because it is the only one which by its very
  definitions requires past experiences in the
  sense of learning some rule.

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• 5. SHADING AND LIGHTING- Surface of the object
  nearest the light source is the brightest. As the
  surface recedes from the light it appears less
  bright and more darkly shadowed.
• 6. ELEVATION- Elevation may play a role in the
  perception of both relative and absolute
  distance. The objects appearing higher in the
  visual field are generally perceived as being
  located at a greater distance from the viewer
  than are objects that appear lower to various
  field.

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• 7. TEXTURE GRADIENTS When we look at any
  textured surface, the elements composing the
  texture become denser as distance increases.
• 8.ARIEL PERSPECTIVE- When viewing the terrain
  outdoors objects in the far distance are
  generally seen less clearly than objects located
  close.