Module 6

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• Module 6
• Perception
• Perception
• Perception
• Perception

Module 6 Perception Perception Perception Percepti
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Module 6 Perception Perception Perception Percepti
on
Module 6 Perception Perception Perception Percepti
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SENSATION VERSUS PERCEPTION

• Basic Differences
• Sensations
• our first awareness of some outside stimulus.
• outside stimulus activates sensory receptors,
  which in turn produce electrical signals that are
  transformed by the brain into meaningful bits of
  information
• Perceptions
• the experience we have after our brain assembles
  and combines thousands of individual sensations
  into a meaningful pattern or image

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SENSATION VERSUS PERCEPTION (CONT.)

• Changing sensation into perception
• Stimulus
• change of energy in the environment, such as
  light waves, sound waves, mechanical pressure, or
  chemicals
• Transduction
• change physical energy into electrical signals
• electrical signals are changed into impulses that
  travel into the brain
• Brain
• impulses from senses first go to different
  primary areas of the brain

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SENSATION VERSUS PERCEPTION (CONT.)

• 4. Changing sensation into perception
• brain association areas
• sensation impulses are sent to the appropriate
  association area in the brain
• 5. Personalized perceptions
• each of us has a unique set of personal
  experiences, emotions, and memories that are
  automatically added to our perceptions by other
  areas of the brain

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PERCEPTUAL THRESHOLDS

• Becoming aware of a stimulus
• Absolute threshold
• absolute threshold is the smallest amount of
  stimulus energy (such as sound or light) that can
  be observed or experienced
• the intensity level of a stimulus such that a
  person will have a 50 chance of detecting it

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PERCEPTUAL THRESHOLDS

• Estimated Absolute Thresholds
• Vision A candle flame from 30 miles away at
  night.
• HearingA tick of a watch from 20 feet away in a
  quiet room.
• Touch A bees wing falling on your cheek from a
  height of 1 centimeter.
• Smell A drop of perfume diffused through a three
  room apartment.
• Taste A gram of salt in 500 liters of water.

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PERCEPTUAL THRESHOLDS (CONT.)

• Subliminal stimulus
• has an intensity that gives a person less than a
  50 chance of detecting the stimulus

Priest in Little Mermaid
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Taken from original packaging
                         
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Lions exhale
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Will this make you buy popcorn?
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PERCEPTUAL THRESHOLDS (CONT.)

• E. H. Weber
• worked on the problem of how we judge whether a
  stimulus, such as loud music, has increased or
  decreased in intensity
• . called Webers law
• concept of just noticeable difference (JND)
• the increase in intensity of a stimulus needed to
  produce a just noticeable difference grows in
  proportion to the intensity of the initial
  stimulus.

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Just Noticeable Difference

• Imagine you are holding a brick in one hand and a
  dime in the other. Which hand would require more
  added weight for you to notice the change?
• - The hand with the brick of course.
• The more intense a stimulus is, the more change
  is needed for you to notice the change.

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RULES OF ORGANIZATION

• Gestalt school of psychology
• the whole is greater than the sum of its parts
• Gestaltists
• believe our brains follow a set of rules that
  specify how individual elements are to be
  organized into a meaningful pattern, or perception

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RULES OF ORGANIZATION (CONT.)

• Organizational rules
• rules of organization specify how our brains
  combine and organize individual pieces or
  elements into a meaningful perception
• 1. Figure-ground
• states in organizing stimuli, we tend to
  automatically distinguish between a figure and a
  ground
• 2. Similarity
• states in organizing stimuli, we group together
  elements that appear similar

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RULES OF ORGANIZATION (CONT.)

• Organizational rules
• 3. Closure
• states in organizing stimuli, we tend to fill in
  any missing parts of a figure and see the figure
  as complete
• 4. Proximity
• states in organizing stimuli, we group together
  objects that are physically close to one another
• 5. Continuity
• states in organizing stimuli, we tend to favor
  the smooth or continuous paths when interpreting
  a series of points or lines

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PERCEPTUAL CONSTANCY

• Size, shape, brightness color constancy
• Size constancy
• refers to our tendency to perceive objects as
  remaining the same size even when their images on
  the retina are continually growing or shrinking
• Shape constancy
• refers to our tendency to perceive and object as
  retaining its same shape even though when we view
  it from different angles, its shape is
  continually changing its image on the retina

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Young children cannot conclude that glass A and B
have the same amount because of the shape of the
vessel. Can you?
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Size Constancy
Size Constancy dependence of apparent size on
receding surface
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Shape Constancy
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PERCEPTUAL CONSTANCY (CONT.)

• Size, shape, brightness color constancy
• Brightness constancy
• refers to the tendency to perceive brightness as
  remaining the same in changing illumination
• Color constancy
• refers to the tendency to perceive colors as
  remaining stable despite differences in lighting

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Brightness Constancy
What is truly remarkable is that we have no
trouble recognizing these sheep even in the
presence of blotchy shadows. We know they are
about the same size and value contrast as sheep
even if there were no shade or sun blotches.
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Color Constancy
Do you have trouble identifying the same pieces
of fruit as their color reflects itself
differently on your eye?
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DEPTH PERCEPTION

• Binocular (two eyes) depth cues depends on the
  movement of both eyes. They give us
• Depth perception
• the ability of your eye and brain to add a third
  dimension, depth, to all visual perceptions, even
  though images projected on the retina are in only
  two dimensions, height, and width. Its done
  because of two things.

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DEPTH PERCEPTION (CONT.)

• 1. Convergence
• refers to a binocular cue for depth perception
  based on signals sent from muscles that turn the
  eyes
• 2. Retinal disparity
• refers to a binocular depth cue that depends on
  the distance between the eyes

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DEPTH PERCEPTION (CONT.)

• Monocular depth cues
• produced by signals from a single eye
• 1. Linear perspective
• monocular depth cue that results as parallel
  lines come together, converge, in the distance
• 2. Relative size
• monocular depth cue that results when we expect
  two objects to be the same size and they are not
• 3. Interposition
• monocular depth cue that comes into play when
  objects overlap

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DEPTH PERCEPTION (CONT.)

• Monocular depth cues
• 4. Light and shadow
• monocular depth cues where brightly lit objects
  appear closer, while objects in shadows appear
  farther away
• 5. Texture gradient
• monocular depth cue in which areas with sharp,
  detailed texture are interpreted as being closer
  and those with less sharpness and poorer detail
  are perceived as more distant

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DEPTH PERCEPTION (CONT.)

• Monocular depth cues
• 6. Atmospheric perspective
• monocular depth cue that is created by the
  presence of dust, smog, clouds, or water vapor
• 7. Motion parallax
• monocular depth cue based on the speed of moving
  objects

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ILLUSIONS

• Strange perceptions
• Illusion
• a perceptual experience in which you perceive an
  image as being so strangely distorted that, in
  reality, it cannot and does not exist

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ILLUSIONS
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Dali
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• Impossible figures
• perceptual experience in which a drawing seems
  to defy basic geometric laws

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The purpose in the end is to show you how what
you and your brain think you see, is not what you
see. See!
Dali