Visual Perception in Cognitive Psychology: Brain Systems and Theories

Visual Perception Content

Lingnan Institute of Further Education
PSY003 Introduction to Cognitive Psychology
Lecture 2
Visual perceptionContent
Brain System
What is perception?
Approaches of Perception
Neurons and the Environment
Perception and ActionFive senses
Sight
Smell
Hearing
Touch
Taste

Localization of Function

1Localization of Function
Specific functions are served by
specific areas of the brain
Cognitive functioning breaks
down in specific ways when
areas of the brain are damaged
Cerebral cortex (3-mm thick
layer that covers the brain)
contains mechanisms
responsible for most of our
cognitive functions
Cerebral cortex
BrainstemLobes of the cerebral cortex
Frontal lobe 腦 前 葉
(sense of self, motor control,
and higher mental abilities
such as reasoning and planning)
Parietal lobe 頂 葉
(sensation such as
touch, temperature,
and pressure)
Occipital 枕 葉
lobe
(vision)
聶 葉
Temporal lobe
(hearing and
language)
CCengage LearningLobes of the Cerebral Cortex
Frontal Lobe
Reasoning and planning
Language, thought, memory, motor functioning
Parietal Lobe
Touch, temperature, pain, and pressure
Temporal Lobe
Auditory and perceptual processing
Language, hearing, memory, perceiving forms
Occipital Lobe
Visual processingLocalization of Function: Perception
Primary receiving areas for the senses
Occipital lobe: vision
Parietal lobe: touch, temperature, pain
Temporal lobe: hearing, taste, smell
Coordination of information received from
all senses
Frontal lobe

From Sensation to Perception

From sensation to perception
Stimulus
energy
Light, sound,
smell, etc.
Sensory
receptors
Eyes, ears,
nose, etc.
Neural
impulses
Brain
Visual, auditory,
olfactory areas
1
A
D
Sensation
PerceptionRaw Energy
Light
Retina
Image of
tree on
retina
Sensation
Optic
nerve
Electrical
signal to
brain
(c)2011 Cengage Learning
TransductionLaw of specific nerve energies (LOSNE)
1838, Johannes Muller
Stimulation excites a particular nerve establish a
special kind of energy unique to that nerve.
Brain interprets action potentials from
Auditory nerve as sounds
Optic nerve as light
Olfactory nerve as odours
Taste buds as taste
Skin sensory receptors as touch, pressure, pain, etcSensation and Perception
Sensation The stimulation of sense organs
Absorbing raw energy (e.g., light waves, sound
waves) through our sensory organs
Transduction
Conversion of this energy to neural signals
Attention
Concentration of mental energy to process incoming
information
Perception The mental process of organizing
sensations into meaningful patterns
selecting, organizing, and interpreting these signalsSensation and Perception
Energy contains information about the world
(usually incomplete, full of noise, and distorted)
Accessory structure modifies energy
Receptor transduces energy into a neural
response
Sensory nerve transmits the coded activity to the
central nervous systemSensation and Perception
Thalamus
processes and
relays the neural
response
◼
Relayed to
specialized areas of
the cortex
◼
Perception of the
world is created
Frontal lobe
Thalamus
Hippocampus
Amygdala
Hypothalamus
Olfactory bulb

Understanding Perception

What is Perception?

What is perception?
Bottom-up processing
Perception may start with the senses
Incoming raw data
Energy registering on receptors
Top-down processing
Perception may start with the brain
Person's knowledge, experience, expectations
Top-down Modulation
(internally-driven attention)
Perception
(externally-driven attention)
Bottom-up processingTop-down
Bottom-up
(c)2011 Cengage Learning
Perception is determined by three sources of
information: (1) information originating from stimulation
of the receptors; (2) additional information such as the
context in which as object appears; (3) knowledge or
expectations of the perceiver. The dashed arrows
traveling down represents feedback signalsPerception Is ...
The process of recognizing, organizing,
and interpreting information from
senses
Not an exact copy of "the world"
Based on our past experience and
expectations

Approaches to Understand Perception

Approaches to Understand Perception
Direct perception theories
Bottom-up processing
Perception comes from stimuli in the
environment
Parts are identified and put together, and
then recognition occurs
Constructive perception theories
Top-down processing
People actively construct perceptions
using information based on expectationsLight reflected
from Mary
Electrical signals
in brain
Electrical signals
in optic nerve
Image on retina
Representations
of Mary
Figure 3.10 Gil looking at Mary, from page 33, showing that
Mary is represented in Gil's nervous system by an image on
Gil's retina, by electrical signals in Gil's optic nerve, and by
electrical signals in Gil's brain. All of this information repre-
sents bottom-up processing. @ 2015 Cengage Leaming

Perceiving Size: Taking Distance into Account

Perceiving Size: Taking Distance into Account
Perceived size is a function of both bottom-up and
top-down processing
Bottom-up processing
the size of the image on the retina
Top-down processing
the perceived distance of the object
the size of the object relative to other objects in the
environmentO Even though the blobs in
all of the pictures are
identical, they are perceived
as different objects
depending on their
orientation and the context
within which they are
seen.
[ An object on a table in (b),
[ A shoe on a person
bending down in (c), and
[ A car and a person
crossing the street in (d)
blob
(a)
(b)
(c)
(d)
Figure 3.11 "Multiple personalities of a blob." What
we expect to see in different contexts influences
our interpretation of the identity of the "blob"
inside the circles. (Source: Adapted from A. Oliva & A. Torralba,
The role of context in object recognition, Trends in Cognitive
Sciences, 11, Figure 2, 520-527. Copyright @ 2007, with permission
from Elsevier. Photographs courtesy of Antonio Torralba.)

Helmholtz's Theory Of Unconscious Inference (~1860)

Helmholtz's Theory Of Unconscious Inference (~1860)
Top-down theory
Some of our perceptions are the result of
unconscious assumptions we make about the
environment
We use our knowledge to inform our
perceptions
We infer much of what we know about the world
Likelihood principle: we perceive the world in the
way that is "most likely" based on our past
experiences(a)
(b)
(c)
(c)2011 Cengage Learning
The display in (a) is usually interpreted as being (b) a blue
rectangle in front of a red rectangle. It could, however, be
(c) a blue rectangle and an appropriately positioned six-
sided red figure

Perceptual Organization

Perceptual Organization
"Old" view - structuralism
Perception involves adding
up sensations
"New" view - Gestalt
psychologists
The mind groups patterns
according to laws of
perceptual organization
Figure 3.15 According
to structuralism, a
number of sensations
(represented by the
dots) add up to create
our perception of the
face. @ Cengage Leaming1
,
(c)2011 Cengage Learning
5
1

Gestalt: Laws of Perceptual Organization

Gestalt: Laws of Perceptual Organization
Law of good continuation
Lines tend to be seen as following the smoothest
path
28
(c)2011 Cengage Learning
We perceive this pattern as continuous interwoven
strands because of good continuation.(a)
(c)2011 Cengage Learning
(b)Gestalt Laws of Perceptual Organization
Law of good figure (simplicity or pragnanz)
Every stimulus pattern is seen so the resulting structure
is as simple as possible
(a)
(b)
(c)2011 Cengage Learning
Law of simplicity. We see five circles, as in (a), not the
more complex array of nine objects, as in (b).Gestalt Laws of Perceptual Organization
Law of similarity
Similar things appear
grouped together
(a)
Law of similarity. (a) This
display can be perceived as
either vertical columns or
horizontal rows of circles; (b)
most people perceive vertical
columns of circles, due to
similarity of shape
(b)
(c)2011 Cengage LearningFigure 3.21 This photograph, Waves, by Wilma
Hurskainen, was taken at the exact moment that the front
of the white water aligned with the white area on the
woman's clothing. Similarity of color causes grouping;
differently colored areas of the dress are perceptually
grouped with the same colors in the scene. Also notice
how the front edge of the water creates grouping by good
continuation across the woman's dress.
Courtesy of Wilma HurskainenGestalt Laws of Perceptual Organization
Law of familiarity
Things are more likely to form groups if the
groups appear familiar or meaningful
(c)2011 Cengage Learning
Caption: The Forest Has Eyes by Bev Doolittle (1985). Can you find
13 faces in this picture? (Source: "The Forest Has Eyes" 1984 Bev
Doolittle, courtesy of The Greenwich Workshop, Inc.)Gestalt Laws of Perceptual Organization
Gestalt laws often provide accurate information
about properties of the environment
Reflect experience
Experience is important but does not overcome
perceptual principles
Gestalt laws are intrinsic

Physical Regularities

Physical Regularities:
◼
are regularly occurring physical properties of
the environment.
(a)
(b)
(c)2011 Cengage Learning
(a) look like indentations in the sand and (b) look like mounds of sand.
(b) Note that (b) is upside down picture of (a)

Semantic Regularities

Semantic Regularities
The meaning of a given scene is related to what is
happening within that scene, and semantic
regularities are the characteristics associated with
the functions carried out in different types of scenes.
A scene schema is the knowledge of what a given
scene ordinarily contains
e.g., if you think of a professor's office, what would you
expect to find/see there?A
B
C
Context scene
Target object
(c)2011 Cengage Learning
Caption: Stimuli used in Palmer's (1975) experiment. The scene at the left is presented
first, and the observer is then asked to identify one of the objects on the right.
Semantic Regularities: are the characteristics associated
with the functions carried out in different types of scenes.

Neurons and the Environment

Neurons and the Environment
Some neurons respond best to
things that occur regularly in
the environment
Horizontals and verticals
Neurons becomes tuned to
respond best to what we
commonly experience
Experience-dependent plasticity
Bruce Goldstein
Figure 3.22 In these two scenes from nature, horizontal
and vertical orientations are more common than oblique
orientations. These scenes are special examples, picked
because of the large proportion of verticals. However,
randomly selected photos of natural scenes also contain
more horizontal and vertical orientations than oblique
orientations. This also occurs for human-made buildings
and objects.