This PowerPoint helps students to consider the concept of infinity.
1 perceptual process
1. Cognition (mental activity or mental processes)
Cognition (Latin: cognoscere, "to know" or "to
recognize") refers to the acquisition, storage,
transformation, and use of knowledge. Cognition
can be natural or artificial, conscious or
unconscious.
It is a faculty of mental processes such as
learning, memory, perception, thinking, problem
solving, reasoning, decision making etc.
2. Characteristics
The cognitive processes are active, rather than
passive
The cognitive processes are remarkably
efficient and accurate
The cognitive processes Handle positive
information better than negative information
The cognitive processes are interrelated with
one another, they do not operate in isolation
many cognitive processes rely on both bottom-
up and top-down processing
3. Sensation and Perception
Sensation
The processes by which our sense organs
receive information from the environment.
Transduction
The process by which physical energy is
converted into sensory neural impulses.
Perception
The processes by which people select,
organize, and interpret sensations.
5. sensation
Sensation is defined as:
Irreducible elements from which perceptions
are formed as experiences which are simpler
and less meaningful than perceptions and
uninfluenced by learning and other
psychological processes such as emotion and
motivation (Hebb, 1972; Scharf, 1975).
6. Problems of perception
No direct physical contact with the visual
elements is required to appreciate there nature.
How do we form the impressions of the
quantitative and qualitative aspects of external
objects?
Does the real physical world actually exist
independently of our experience? If so, how we
can come to know its properties and how truth
of that knowledge be determined?
7. Problems…
How percepts are constructed from the
interaction of physical energy (light) and the
perceiving organism.
Proximal and distal stimuli are different but
our perceptions are generally accurate or
veridical enough to adjust ourselves in the
environment.
Some times percept have properties
considerably different form proximal
stimulus.
8. Components of perception
Distal stimulus
Distal stimulus refers to a physical aspect of the
external environment, or the physical energy
which comes from the eternal source. For
example, object in the external environment
such as, table, fan etc.
Proximal stimulus
It refers to the physical energy coming from the
external source strikes on the sensory receptors.
9. Components…
Input and output
Input refers to the sensation of stimulus and
output refers to behavior made in response to
the input.
Percept
Out come of perception is known as percept.
Recognizing an object as flower would be an
example of percept.
10. Difference between proximal and distal
stimulus
Much of the light coming form distal source is
scattered by molecules and lost before it reaches
the receptors of the eye.
Resulting proximal image is much smaller,
inverted relative to the distal stimulus
Proximal stimulus is partly under the control of
observer’s head and eye movements.
Information in the form of electromagnetic
energy is changed in the neural impulses
(transduction).
11. Defining perception
According to Morgan and King, “perception is
the way the world look (sounds, feels, tastes
and smells too)”.
According to Zigher (1985), perception refers
to the interpretation of sensory information, as
a constructive and creative process which
endows sensory experience with meaning.
12. Defining…
Perception is a process by which
individuals organize and interpret their
sensory impressions in order give meaning
to their environment for making better
adjustment with it.
Perception is a process by which we
recognize and interpret or give meaning to
raw material provided by sensory system
with the help of other psychological
processes such as, learning, memory,
emotions and motivation.
13. Defining…
Perception is the process of creating an
internal representation of the out side world
(internal representation is a joint product of
bottom up and top-down processing).
Perception is the interpretation of the
information provided by sensory system.
14. Perception is active, selective and
relatively more automatic higher
mental process through which we
experience or interpret our
immediate surrounding.
15. Properties of perception
Perception is interpretation of physical
energy or giving meaning to it.
In perception, registered stimuli by the
senses are gathered and interpreted with the
help of previous knowledge.
Perception combines aspect of both the
outside world (the stimulus) and inner
world (previous knowledge).
16. Properties …
Perception is relatively more automatic
process, required less effort than other
cognitive tasks, such as problem solving of
decision making.
Perception is influenced by other
psychological processes such as motivation
and emotion.
Perception is an active mental process
involves both top-down and bottom-up
processing.
17. Concepts in perception
Physical- external or internal stimulus such
as wave length, intensity etc.
Physiological- stimulation of sensory
system: neural activity- excitation-
inhibition; sensory modality: transduction
Behavior
Subjective experience
19. Approaches to perception
Structuralism
Wilhelm Wundt and Edward Bradford
Titchner (1867-1927)
Structuralisms emphasized on the study of
the structure of perception. Its goal was to
uncover the simplest, most basic elements
of conscious experience (bottom-up
processing).
20. Constructivist Approach
Emphasized on the active nature of perceptual process.
Influenced by empiricism.
Proposed that the percept is more than the information
coming form stimulus.
Some constructive processes occur within the observer.
These are mediating processes between physical world
and its perception.
Our perception is a mental construction based on our
cognitive strategies, past experiences, biases,
expectations, motives, attention, and other personal
characteristics
21. Direct perception approach (James J.
Gibson, 1904-1979)
Stimulus contains important information
necessary for perception
Past experiences are not important
Perception depends on the characteristics of
stimuli (subjective variables are not
important)
It is also known as ecological approach
because it focuses on the adaptive link
between the perceiving organism to its
physical environment.
22. Computational Approach
(David Marr, 1945-1980)
Involves mathematically oriented analysis
of certain aspects of visual perception
derived form computer simulation and AI.
Accepts Gibson’s basic idea of direct
perception but also proposes that perception
of characteristics such as lines, edges,
borders, contours, motion, and other
discontinuity.
23. Beliefs of the information-processing
approach
Information is processed in stages
Information is processed serially
The nature of information changes stage to
stage
Information processing is affected by several
factors (noise)
It uses both bottom-up and top-down processing
It is a mediating process between input and
output
24. Gestalt approach
(German: Gestalt - "shape" or "figure")
Berlin School
Kurt Koffka, Max Wertheimer, and Wolfgang
Köhler (students of Carl Stumpf) are the
founder of this school. The 'Gestalt' or 'whole
form' approach sought to define principles of
perception -- seemingly innate mental laws
which determined the way in which objects
were perceived.
25. Gestalt: Basic idea
Operational principle of the brain is holistic,
parallel, and analog, with self-organizing
tendencies
“The whole is greater than the sum of the
parts"
Opposed to structuralism and Wundt
Gestalt effect refers to the form-forming
capability of our senses particularly visual
sense.
26. Figure and ground
Properties of figure ground
Figures hold more memorable association than
the ground.
Figures are seen as being in front of the ground.
The ground is seen as uniformed material and
seems to extend behind the figure.
The contour separating the figure from the
ground appears to belong to the figure.
Compared to ground, perception of figure is
effortless
28. Laws of pragnanz
The fundamental principle of gestalt
perception is the law of prägnanz (German
for pithiness).
The physiological organization will always
be good. Good refers to the simplest and
most stable.
We tend to order our experience in a
manner that is regular, orderly, symmetric,
and simple.
29. Gestalt laws of perceptual organization
Gestalt psychologists modified Law of
prägnanz and given laws which
hypothetically allow us to predict the
interpretation of sensation. These laws are
called "gestalt laws".
31. Perceptual Organization
Reversible Figures
Drawings that one can
perceive in different
ways by reversing
figure and ground.
Gestalt Psychology
School of thought
rooted in the idea that
the whole is different
from the sum of its
parts.
33. Perceptual Organization
Gestalt Laws of Grouping
Proximity
Seeing 3 pair of lines in A
Similarity
Seeing columns of orange
and red dots in B
Continuity
Seeing lines that connect
1 to 2 and 3 to 4 in C
Closure
Seeing a horse in D
39. General Perceptual Psychology
Principles of Perceptual Organization
The principle of synchrony (objects that change
together are grouped together)
40. General Perceptual Psychology
Principles of Perceptual Organization
Repetition Discrimination Task - groupings influence
perception and speed of search:
41. Perceptual Segregation
Figure-ground segregation-We are primed to see a
figure in front of a background
Symmetry and perception of figure and ground
42. Perceptual Segregation
Figure-ground segregation-We are primed to see a
figure in front of a background
Area size and perception of figure and ground
43. Perceptual Segregation
Figure-ground segregation-We are primed to see a
figure in front of a background
Orientation and perception of figure and ground
44. Perceptual Segregation
Figure-ground segregation-We are primed to see a
figure in front of a background
Meaningfulness and perception of figure and ground
45. Pattern recognition
Pattern recognition and attention prepare
the raw sensory information for more
complex mental process.
Pattern recognition allows us to perceive a
form in a stimulus and attention is
responsible for our more extensive
processing of some information.
Pattern recognition is the identification of
complex arrangement of sensory stimuli.
46. In pattern recognition raw information is
organized and transformed by sensory
process and compared with information in
other memory storage.
Thus, pattern recognition involves realizing
that a particular pattern is seen before.
47. Bottom up processing (Data driven)
• emphasizes importance of stimulus in PR.
• Information coming from the stimulus is
enough to recognize the pattern.
• Recognition process in initiated by the
parts of the pattern which serves as the
basis for the recognition of whole.
48. Top down processing (conceptually driven)
Emphasizes that concept and high level of
processing influence PR.
Our knowledge about the world help us
identifying patterns.
The process of PR is initiated by a hypothesis
about the whole leading to the identification
of whole and the subsequent recognition of
components.
50. How do we recognize patterns?
Do we identify an object because we have
first recognize it’s components or do we
recognize these part because we have first
identified the object?
The problem that, whether the recognition
process is initiated by the parts of the pattern
or whether it is initiated by a hypothesis
about the whole (hypothesis testing) is
called prasing paradox.
51.
52. A: Template Matching Theory
Templates are specific patterns that are
stored in memory.
Stimulus is compared with a set of
templates.
We recognize the stimulus as the template
that matches most closely.
Stimulus must fit the template precisely.
53. Problems of TMT
If a number of templates match or come close
(not one)-
We need further processing to sort out
which template is most appropriate which
will take much time than it actually takes.
It does not explain how perception works.
with the development of technology our
experiences change thus, how and when
templates are created?
54. How different patterns are recognized as
same despite the wide variation in the size,
shape, orientation etc. (e.g. recognizing
hand writing of different people).
It works for simple latter and simple objects.
55. B: Feature Analysis
Feature analysis model assumes that instead of
processing stimuli as whole units, we break them
down into their components. We recognized those
parts to infer what the whole represents.
There is physiological mechanism in retina and in
the cortex. These are called feature detectors.
Some cells respond to boarders between light and
dark called edge detectors.
Movement detectors are called bug detectors.
Horizontal and vertical line detectors are also found
in the cortex.
56. 1: Distinctive feature approach
Discrimination among letters is made on the basis of
small no of characteristics called distinctive features.
We store a list of feature components for each letter.
E.g. Q has a round closed shape and a diagonal line.
Gibson (1969) demonstrated that people require long
time to decide whether some letters are different
from one another when the letter share large number
of critical features.
57. For example, P and R are similar on a large
number of critical features; and G and M are
different from each other on a large number of
critical features.
Differentiation between G and M takes less time as
compared to differentiation between P and R.
In distinctive feature approach pattern recognition
involves detecting specific important parts while in
TMT emphasizes prototype and entire recognition
of entire shape.
58. Problems of distinctive feature approach
Explain simple shape or features recognition such as
letter recognition.
It does not explain physical relationships. For
example, T and L are similar but they are recognize
distinctly on the basis of relationship. For example,
T has a vertical line supports a horizontal line in the
middle. Where L has the vertical line rests at the
side of the horizontal line.
It explains simple letter recognition but natural
features, shapes are more complex. How can we
recognize a horse?
59. 2: The Computational Approach
(David Marr (1982)
Images- Identification of object’s edges by
combining intensity of the image
Primal sketch- edges are organized into
abstract representation
2 ½ D sketch- primal sketch is converted
into 2 ½ D sketch (contours, shade, rough
depth)
3 D image- Describes shapes and their spatial
organization of the object.
60. Perceptual Organization
Identifying Objects
Geons (geometric
icons) are simple 3D
component shapes.
A limited number are
stored in memory.
Geons are combined to
identify essential
contours of objects.
61. Perceptual Constancies
Size Constancy
The tendency to view an object as constant
in size despite changes in the size of the
retinal image.
Shape Constancy
The tendency to see an object as keeping its
form despite changes in orientation.
62. Perceptual Constancies
The Ames Room
A specially-built room that
makes people seem to
change size as they move
around in it
The room is not a
rectangle, as viewers
assume it is.
A single peephole prevents
using binocular depth cues.
63. Perceptual Constancies
Shape Constancy
Even though these images cast shadows of
different shapes, they still are seen as round.
64. Perceptual Constancies
Size Constancy
Tendency to view an object as constant in
size despite changes in the size of the
retinal image.
http://www.psychologie.tu-dresden.de/i1/kaw/diverses%20Material/www.illusionworks.com/assets/images/constancy.jpg
66. Binocular Cues
Depth cues that
require the use of
both eyes
Enables people to see
in three dimensions.
67. Retinal Disparity
A binocular depth cue resulting from
slightly different images produced by
the separation of the retinas in the left
and right eye
Is most effective when the item is quite
close to the person
71. Retinal Disparity Demo
1. Roll a piece of scrap paper into a tube shape.
2. Hold it to your right eye as if it were a telescope
3. Look through the tube focusing on an object
on a blank wall in front of you.
4. Keeping both eyes open, hold your open left
hand beside the tube…continue to focus on
the object on the wall.
5. The images should fuse and ….
72. Convergence
A binocular depth cue related to the
tension in the eye muscles when the
eyes track inward to focus on objects
close to the viewer
The more tension in the eye muscle, the
closer the object is
Works best at close distances
75. Monocular Depth Cues
1. Relative Size
Using the perceived
size of a familiar
object to determine
depth
The larger the
object appears, the
closer the object is
to the viewer
76. Monocular Depth Cues
2. Relative Motion
A person who is moving can determine
depth by focusing on a distant object.
Objects further away than the object of
focus will appear to move in the same
direction as the subject is moving.
Objects closer than the object of focus
will appear to move in the opposite
direction.
78. Monocular Depth Cues
3. Interposition
Method of
determining depth
by noting that
closer objects
partially obstruct
the more distant
objects
Also called
“overlap”
79. Monocular Depth Cues
4. Relative Height
Method of
determining depth
by noting that
distant objects
appear higher in
your field of
vision than do
closer objects
80. Monocular Depth Cues
5. Texture Gradient
Method of determining depth by noting that distant
objects have a smoother texture than nearby objects
Can see individual blades of hay, but in the
Distance, the hay seems to have a smoother
Texture.
81. Monocular Depth Cues
6. Relative Clarity
Method of
determining
depth by noting
that distant
objects are less
clear than
nearby objects
Tends to work Paris Street: A Rainy Day by Gustave
outdoors Caillebotte
82. Monocular Depth Cues
7. Linear Perspective
Method of
determining depth
by noting that
parallel lines appear
to converge in the
distance As parallel lines become more
The lines appears to distant from us, they appear to get
closer together - like the sides of
eventually merge on the gray bit at left. Their
the horizon. apparent closeness is therefore a
cue to their relative distance from
us.
83. Depth and Dimension
8.The Visual Cliff
Devised by Eleanor
Gibson and Richard Walk
to test depth perception in
infants and animals.
Provides visual illusion of
a cliff.
Caregiver stands across
the gap.
Babies are not afraid until
about the age they can
crawl.
84. Perceptual Set
What is seen in the center figures depends on the
order in which one looks at the figures:
If scanned from the left, a man’s face is seen.
If scanned from the right, a woman’s figure is
seen.
85. Perceptual Set
Context Effects
The same physical
stimulus can be
interpreted differently
depending on
perceptual set, e.g.,
context effects.
When is the middle
character the letter B
and when is it the
number 13?
86. The World of Illusions
The Müller-Lyer Illusion
Illusion in which
the perceived
length of a line is
altered by the
position of other
lines that enclose it
87. The World of Illusions
The Ponzo Illusion
Illusion in which the
perceived line length
is affected by linear
perspective cues.
Side lines seem to
converge
Top line seems farther
away
But the retinal images
of the red lines are
equal.
88. The Continuing Controversy
The ganzfield procedure
Researchers disagree about the reliability of
studies done to replicate the ganzfield test.
Visit www.randi.org/ for information about
the James Randi Educational Foundation’s
million-dollar paranormal challenge.
Perceptual constancies – perception of entire object does not change, even though some of the sensory items have changed Size Constancy Tendency to view an object as constant in size despite changes in the size of the retinal image. Wundt had no way to explain why this happened either, just like the phi phen.