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What is Perception
• Perception is the process through which
people take raw sensations from the
environment and interpret them, using
knowledge , experience and understanding of
the world, so that the sensation become
Factors affecting perception
• Past Experience
The Influence of Motivation
• The extent of our motivation
will affect the speed and way
in which we perceive the
• For example, food products
will seem to be brighter in
color when you are hungry.
The Influence of Expectation
• What we see is, at least to
some extent, influenced by
what we expect to see.
• Expectation can be useful
because it allows the
perceiver to focus their
attention on particular
aspects of the incoming
• However, it can distort
• For example, we may fail to notice printing errors or
writing errors because we are expecting to see
particular words or letters.
The Influence of Emotion
• Emotions affect our perception on a
physiological level. Physiologically our
current emotion could effect our
perceptions by altering how the
information is taken in.
• We find people with squeaky voices
who speak very rapidly as extremely
annoying if we are tired, but If we are
in a good we probably wouldn't find
Influence of culture
• Culture plays a major role in how we
view the world, and how we take in the
things around us.
• In Russia Red revolution.
• In China, brides wear Red and it is
considered a Good Luck color. To most
• Asians Red means happiness and
prosperity. In India Red is a symbol of
• In the Middle East the color symbolism
of Red is Danger and Evil.
Influence of past experience
• Past experiences can also
affect perception because
those experiences were being
stored in the mind of an
Perception and communication
• Perception and communication
are related as Perception is a
necessary step toward the
process of communication.
• This process of perception and
communication is two-fold.
• A person first communicates with
him or herself based on the way
he or she perceives the sensory
data from different senses
through a process known as
• In terms of interpersonal communication,
perception and communication are linked
in the various ways that perception guides
the way people relate and communicate
with each other.
Perception affects communication
• In any type of communication there
is always the chance that the
intended meaning is lost in the
• Robert L. Scott, a communication
scholar said that "Nothing is clear in
and of itself but in some context for
• Everybody perceives things
differently. That does not mean that
one person is right and the other
Perception And Psychology
Perception in Psychology
• In order to receive information from the
environment we are equipped with sense organs e.g.
eye, ear, nose.
• Each sense organ is part of a sensory system which
receives sensory inputs and transmits sensory
information to the brain
• There are several theories that psychologists have
that show us how we perceive the world. These
theories (except bottom-up and top down) are not in
opposition to each other.
• A major theoretical issue on which psychologists are
divided is the extent to which perception relies
directly on the information present in the stimulus.
• This controversy is discussed with respect to Gibson
(1966) who has proposed a direct theory of
perception which is a 'bottom-up' theory, and
Gregory (1970) who has proposed a constructivist
(indirect) theory of perception which is a 'top-down'
Gibson’s 'bottom-up' theory
• Gibson argues that there is enough
information in our environment to make
sense of the world in a direct way.
• As we move through our environment, objects
which are close to us pass us by faster than
those further away.
Evidence to Support Gibson’s
• ‘Light and the Environment
• Changes in the flow of the
optic array contains
important information about
what type of movement is
• Gibson claims that the
center of that movement
indicates the direction in
which the perceiver is
• ‘The Role of Invariants
• Gibson notes that we
rarely see a static view
of an object or scene.
When we move our
head and eyes or walk
move in and out of our
• Two good examples of
invariants are texture
and linear perspective.
• Affordances are cues in the environment that
aid perception. Important cues in the
• Optical Array
• Relative Brightness
• Texture Gradient
• Relative Size
Evidence against Gibson’s Theory:
• Gibson’s theory of perception provides an
explanation for fast accurate perception, however he
fails to explain why perceptions are sometimes
• Gibson’s theory fails to explain naturally occurring
• One of the weakest aspects of Gibson’s theory is the
concept of affordances. Humans live within a
particular cultural context in which knowledge about
the use of objects is learned rather than ‘afforded’.
Gregory’s Top-Down Theory of Perception
• Gregory sees perception as a hypothesis – he
argues that formation of incorrect hypotheses
will lead to errors in perception
• Gregory notes that a lot of information
reaches the eyes but is lost by the time it
reaches the brain (about 90% is lost).
Evidence to Support Gregory’s Theory:
• ‘Perception allows behavior to be generally
appropriate to non-sensed object
• For example, we respond to certain objects as
though they are doors even though we can
only see a long narrow rectangle as the door is
• Perceptions can be interpreted
• if you stare at a cross on the cube
the orientation can suddenly
change or ‘flip’, then one pattern
produces two perceptions.
• Gregory argues that this occurs
because the brain develops two
reasonable hypotheses and is
unable to decide between the
• highly unlikely objects tend to be mistaken for
• Gregory tested this with a hollow mask he
argues that although the audience was aware
• The mask was hollow (they were aware of the
environment) they were still tricked by the
Evidence against Gregory’s
• The Nature of perceptual hypotheses’
If perceptions make use of hypothesis testing
the question can be asked ‘what kind of
hypotheses are they?
• ‘Perceptual development’
If we all have to construct our own worlds
based on past experiences why are our
perceptions so similar, even across cultures
• ‘Sensory Evidence’
The main criticism of Gregory’s theory is that
his evidence is not ecologically valid.
The stimulus’ that he uses is artificial and
does not apply to the real world. Gibson
argues that his theory is more realistic
because he uses real world application.
Signal Detection Theory
• This theory examines how outside influences effect
• For example, if I am really hungry for meat, I am
more likely to smell a burger than if I was not. If I
think I smell a burger, but it is not really there, that is
called a false positive (perceiving stimuli that is not
• Thresholds are the idea that our senses have
• First there is the absolute threshold, which is
the smallest amount you can just sense
• For example, If you can just barely hear a
sound- then it is at your absolute threshold for
• Another type of threshold is called the difference
• The difference threshold the smallest amount of
change needed in a stimulus before we notice the
• If you are watching T.V and someone is singing any
song in the next room. You grab the controller and
raise the volume one bar.
• That change in volume was under your difference
• Our eyes are like mirrors,
reflecting information to the back
of our retinas.
• Objects that are closer to us
produce bigger images on our
• Objects viewed from different angles will
produce different shapes on our retinas, but
we know that the shape of the object remains
• We perceive objects as being a constant color
even as the light reflecting off the object
• A white piece of paper indoors reflects
considerably less light than does a black lump
of coal outside on a bright, sunny day. Yet the
paper looks white, and the coal black.
• The concept of depth
is one of the most
studied aspects of
• Researcher E.J. Gibson
conducted a very
called the visual cliff
humans are able to see
Types of perception
• Amodal perception is one of the
most recognizable types of
perception in psychology.
• It is the observation and
interpretation of things in terms
of depth and motion.
• Color perception, on the other hand,
describes the way the visual senses, denoting
the eyes, observe hues and contextualize
them in the environment.
• The other types of perception in psychology
include those that interpret verbal output.
• Speech perception, for one, helps in not only
understanding one another, but deducing
meaning from mere sound.
• Depth perception also acts
as one of the types of
• It is the visual ability to
judge the relative distance
of objects and the spatial
relationship of objects at