POWERPOINT PRESENTATION ON COGNITIVE PSYCHOLOGY ABOUT VISUAL PERCEPTION

**Visual perception** is the process by which the brain interprets information from the eyes to create a mental representation of the visual world. It involves a complex series of steps, including:

1. **Light Detection:** The retina, a light-sensitive layer at the back of the eye, captures light and converts it into electrical signals.
2. **Feature Detection:** Specialized cells in the retina and brain detect specific features of visual information, such as edges, lines, and colors.
3. **Perceptual Organization:** The brain groups and organizes visual features into meaningful objects and scenes.
4. **Object Recognition:** The brain compares incoming visual information to stored mental representations of objects to identify and recognize them.
5. **Depth Perception:** The brain uses cues such as binocular disparity, relative size, and occlusion to create a sense of depth and distance.

**Factors Affecting Visual Perception:**

* **Attention:** Focusing attention on specific aspects of a visual scene can enhance perception.
* **Expectation:** Our expectations about what we will see can influence how we interpret visual information.
* **Context:** The surrounding environment can provide clues about the meaning of visual stimuli.
* **Learning and Experience:** Past experiences and learning can shape our visual perception.

**Visual Illusions:**

Visual illusions are perceptual errors that occur when the brain misinterprets visual information. They can be caused by a variety of factors, such as ambiguous figures, contrast effects, and motion parallax.

**Examples of visual illusions:**

* **The Müller-Lyer illusion:** Two lines of equal length appear to be different lengths due to the angled lines attached to them.
* **The Ames room illusion:** A room with distorted proportions can make people appear to be different sizes.
* **The Stroop effect:** It is difficult to name the color of words that are spelled out in different colors.

**Visual perception is a complex process that is essential for our interaction with the world. It allows us to navigate our surroundings, recognize objects, and communicate with others.**

1. VISUAL
PERCEPTION
Presented By : GROUP 2
Southwestern University PHINMA | 2024

2. OUTLINE
1
•Approaches to Perception: How Do We Make Sense of What We
See?
•Perception of Objects and Forms
•From Sensation to Perception
•The Environment Helps You See
•Deficits in Perception

3. PERCEPTION
•Is the set of processes by which we recognize, organize, and make sense of
the sensations we receive from environmental stimuli (Goodale, 2000a,
2000b; Kosslyn & Osherson, 1995; Marr, 1982; Pomerantz, 2003).



Knowledge is a key to perception.

4. 4

5. 2

6. James Gibson (1966,1979)

•he introduced the concepts of perception and provided a useful
framework for studying perception in his influential work.

3
BASIC CONCEPTS OF PERCEPTION
•DISTAL (far) OBJECT
•INFORMATIONAL MEDIUM
•PROXIMAL (near) STIMULATION
•PERCEPTUAL OBJECT (what you see)

8. GANZFELD EFFECT
• a uniform visual field is called Ganzfeld means ‘complete field’.
PERCEPT

•mental presentation of a stimulus that is perceived.

9. HOW DOES OUR VISUAL SYSTEM
WORK?

10. OVERVIEW
LIGHT ENTERS THE EYE → CORNEA → PUPIL →
LENS → VITREOUS HUMOR → RETINA → RODS &
CONES → OPTIC NERVE → OPTIC CHIASMA →
THALAMUS → VISUAL CORTEX

11. PATHWAYS TO PERCEIVE THE
WHAT AND THE WHERE

12. Dorsal Pathway (Where Pathway):
•Function: Processes location and motion information.
•Path: Ascends from the primary visual cortex in the
occipital lobe to the parietal lobe.
•Deficit Example: Lesions in the parietal lobe can impair
the ability to locate objects.
VISUAL PATHWAYS IN THE BRAIN

13. Ventral Pathway (What Pathway):
•Function: Processes the color, shape, and identity of
visual stimuli.
•Path: Descends from the primary visual cortex to the
temporal lobe.
•Deficit Example: Lesions in the temporal lobe can impair
object recognition.
VISUAL PATHWAYS IN THE BRAIN

14. Alternative Interpretation - What-How Hypothesis:
•Proposed by: Goodale and colleagues.
•Concept: Instead of just "what" and "where," the
pathways relate to "what" an object is and "how" we can
interact with it.
VISUAL PATHWAYS IN THE BRAIN

15. Alternative Interpretation - What-How Hypothesis:
•Ventral Stream (What Pathway): Responsible for object
identification.
•Dorsal Stream (How Pathway): Controls movements
related to the identified objects.
VISUAL PATHWAYS IN THE BRAIN

16. APPROACHES TO PERCEPTION:
HOW DO WE MAKE SENSE OF
WHAT WE SEE?

17. Bottom-Up Theories: These theories suggest that
perception starts with the sensory stimuli taken in by our
eyes, and then the brain processes this data. It is a
data-driven approach.
PERCEPTION THEORIES

18. Top-Down Theories: These theories propose that
perception is influenced by higher-level cognitive
processes, existing knowledge, and expectations.
Perception starts with what we know and expect, then
considers the sensory data.
PERCEPTION THEORIES

19. BOTTOM - UP THEORIES
DIRECT PERCEPTION
TEMPLATE THEORIES
FEATURE MATCHING THEORIES
RECOGNITION - BY - COMPONENTS THEORY

20. Gibson’s Theory of Direct Perception, the information in
our sensory receptors, including the sensory context, is all
we need to perceive anything.
DIRECT PERCEPTION

21. Cues Used in Depth Perception

22. NEUROSCIENCE AND DIRECT PERCEPTION
Neuroscience also indicates that direct perception
may be involves in person perception.

23. TEMPLATE THEORIES
•Template theories suggest that our minds store myriad
sets of templates.

•Template matching theories belong to the group of
chunk-based theories.
NEUROSCIENCE AND TEMPLATE THEORIES
-Letters of the alphabet are simpler than faces and other
complex stimuli. But how do we recognize letters?

25. WHY COMPUTERS HAVE
TROUBLE READING
HANDWRITING?

26. FEATURE - MATCHING THEORIES
•According to these theories, we attempt to match
features of a pattern to features tored in memory,
rather than to match a whole pattern to a template or a
prototype.
THE PANDEMONIUM MODEL
•In this model, metaphoric “demons” with specific
duties recieve and analyze the features of a stimulus.

27. OLIVER SELFRIDGE
•Oliver Gordon Selfridge, was a mathematician and
computer scientist who pioneered the early
foundations of modern artificial intelligence

28. 4 KINDS OF DEMONS:

•Image demons
•Feature demons
•Cognitive demons
•Decision demons

29. RECOGNITION-BY-
COMPONENTS THEORY/ RBC
THEORY
•How do we form stable 3-D mental representations of objects? The
recognition-by-components theory explains it, using simple geometric
shapes.

30. Irving Biederman (1987)
•Seeing with the help of Geometric shape called Geons
These shapes include objects such
as:
•Bricks
•Cylinders
•Wedges
•Cones
•Curved axis counterparts

31. Neuroscience and
Recognition-by-Components Theory
•Geons are viewpoint-invariant, so studies should show that neurons
exist that react to properties of an object that stay the same, no
matter whether you look at them from the front or the side.

33. Context Effect
-Are the influences of the surrounding environment on the
perception (e.g., our perception of “THE CAT”.

-One reason for favoring the constructive approach is that
bottom-up (data-driven) theories of perception do not fully
explain context effects.

36. PERCEPTION OF OBJECTS AND FORMS
VIEWER-CENTERED REPRESENTATION
the individual stores the way the object looks to him or her.
OBJECT-CENTERED REPRESENTATION
the individual stores a representation of the object, independent of its
appearance to the viewer.
LANDMARK-CENTERED REPRESENTATION
information is categorized by its relation to a well-known or prominent.

37. GESTALT LAWS
•Developed in Germany in the early twentieth century.
•It is particularly useful for understanding how we perceive groups of
objects or parts of objects to form integral wholes (Palmer, 1999a,
1999b, 2000; Palmer & Rock, 1994; Prinzmetal, 1995).
•The approach was founded by:
Kurt Koffka (1886–1941)
Wolfgang Köhler (1887–1968)
Max Wertheimer (1880–1943)
•It is based on the notion that the whole differs from the sum of its
individual parts.

38. THE GESTALT PRINCIPLES OF FORM PERCEPTION

39. THE GESTALT PRINCIPLES OF FORM PERCEPTION
Figure Ground

40. •An experiment by Parron and Fagot (2007) showed that only
humans misjudged the size of the central circle in the Ebbinghaus
illusion, whereas baboons did not.

41. PATTERN RECOGNITION SYSTEMS
FEATURE ANALYSIS SYSTEM
recognizing parts of objects and in assembling those parts into
distinctive wholes.
CONFIGURATIONAL SYSTEM
recognizing larger configurations, not analyzing parts of objects or the
construction of the objects.

42. EXAMPLE OF A CONFIGURATIONAL EFFECT
RECOGNITION OF FACES AND HOUSES EXPERIMENT BY FARAH ET AL.
(1998)

43. THE NEUROSCIENCE OF RECOGNIZING FACES AND PATTERNS
•FUSIFORM GYRUS AND EMOTION
Studies indicate that emotional processing increases activation within the fusiform gyrus
when people process faces.
•AUTISM AND EMOTIONAL RECOGNITION
People with autism, who often have impaired emotional recognition, show less
activation in the fusiform gyrus compared to non-autistic individuals.
•FACE PERCEPTION SPECIALIZATION
Not all researchers agree that the fusiform gyrus is specialized solely for face
perception. Some argue that while it shows the greatest activation for face perception,
other brain areas also activate to a lesser degree when perceiving faces.

44. THE NEUROSCIENCE OF RECOGNIZING FACES AND PATTERNS
•EXPERT-INDIVIDUATION HYPOTHESIS
The fusiform gyrus is activated when examining items of visual expertise. For
instance, bird or car experts show fusiform gyrus activation when differentiating
among similar items within their domain of expertise.
•PROSOPAGNOSIA
Prosopagnosia, the inability to recognize faces, highlights the critical role of the fusiform
gyrus. Individuals with this condition can detect emotions but cannot recognize whether
the face belongs to a familiar person.
•SCHIZOPHRENIA AND FACIAL EMOTION RECOGNITION
People with schizophrenia often struggle with recognizing emotions in faces, likely
due to atypical eye movement patterns.

45. THE ENVIRONMENT HELPS
YOU SEE

46. •when our perception of an object remains the same even though
the sensory input (proximal sensation) changes.
PERCEPTUAL CONSTANCIES
TWO MAIN CONSTANCIES:
1.Size Constancy
2.Shape Constancy

47. •The perception that an object maintains the same size despite
changes in the size of the proximal stimulus.
example :
Müller-Lyer Illusion
1. SIZE CONSTANCY

48. •The perception that an object maintains the same shape despite
changes in the shape of the proximal stimulus.
2. SHAPE CONSTANCY

49. DEPTH PERCEPTION
•involves using various cues to perceive the distance of objects.
DEPTH CUES
example : car from far away
small
•these are visual signals that help the brain perceive how far away
objects are.

50. CUES AND MECHANISMS
1. MONOCULAR DEPTH MECHANISM
• visual signals that help us perceive depth and distance using just
one eye.
1. Monocular
2.Binocular

51. example of monucular depth
cues.

52. 2. BINOCULAR DEPTH MECHANISM
• visual signals that help us perceive depth and distance using
both eyes.

54. THE NEUROSCIENCE OF
DEPTH PERCEPTION

55. TWO DISTINCT VISUAL PATHWAYS
•Identifying objects (WHAT)
•How to manipulate them (WHERE OR HOW)


The what-how hypothesis is best supported by evidence of
processing deficits.

56. DEFICITS IN PERCEPTION
Difficulties Perceiving the “What”

AGNOSIA
• trouble perceiving sensory information.
•can perceive the colors and shapes of objects and persons,
but they cannot recognize what objects are.
•have trouble with the ‘what’ pathway.

57. SIMULTAGNOSIA
• an individual is unable to pay attention to
more than one object at a time.


PROSOPAGNASIA
•severely impaired ability to recognize
human faces.

58. Difficulties Knowing the “How”

OPTIC ATAXIA
•impaired ability to use the visual system to guide movement.
•have trouble reaching for reaching things.
•the “how” is impaired.

59. ANOMALIES IN COLOR
PERCEPTION

60. Dichromacy:Rod Monochromacy (Achromacy):
Color perception deficits are more common in men than in women and are
often genetically linked. These deficits can also result from lesions in the
ventromedial occipital and temporal lobes.
TYPES OF COLOR DEFICIENCY
•Least common form of color deficiency.
•Complete absence of color vision.
•Cones are nonfunctional; vision is
limited to shades of gray perceived
through rods.

•Only two out of three mechanisms for
color perception function correctly.
•Results in different types of color
blindness: Red-Green Color Blindness,
Protanopia, Deuteranopia, Tritanopia,
etc.

61. ISHIHARA TEST PLATES

62. WHY DOES IT MATTER?
PERCEPTION IN PRACTICE

63. Impact on Accidents:


Around 50% of all collision accidents
happen because of missed or delayed
perception. This often involves
motorcycles and bicycles.
"looked-but-failed-to-see" accidents
Example

64. Presented By : GROUP 2
Southwestern University PHINMA | 2024
THANK YOU