A Show of Hands
• Remove all rings and bracelets from your right
hand.
• Try to identify your hand.
• How did you form your hypothesis about which
copy was yours and which ones were not? What
types of evidence were involved in your choice?
• What types of perception were involved in your
choice?
• What does this exercise suggest about the
knowledge gained from perception? How reliable
is it?
• Is something more than knowledge necessary for
knowledge to be gained?
Sense Perception
• If for some reason you had to sacrifice one of
your five senses, which would you be most willing
to lose, and which would you be least willing to
lose?
• Most people say they would be most willing to
lose their sense of smell and least willing to lose
their sight.
• This is in large part because we have become a
visually oriented society that often associates
knowledge with sight.
Sense Perception
• In the most general of definitions, sense perception is the physical
response of our senses to stimuli. Our senses include hearing, taste,
touch, smell, and sight, for which we have sense receptors in
different parts of our bodies. We also have internal physical receptors
for awareness of our own bodily sensations, such as hunger, pain, and
arousal.
• Today the study of sense perception is largely the domain of
psychology. In a very simplified fashion, the process of sense
perception is three-fold. First, our sense receptors are stimulated by
sensory information. The brain then translates that sensory
information into sensations such as sound, taste, temperature,
pressure, smell, or sight, for example. Finally, higher centres in the
brain either ignore or recognize the sensations and their meanings,
based on neuronal networks of past association and expectation.
• We do not sense all the stimuli that we're potentially able to sense.
There's too much going on in our environment for us to handle, and
we unconsciously ignore many stimuli.
Perception as the Search for Meaning
• One of the axioms of perception is
that we assume that the human
mind involuntarily creates
meaning from stimuli.
• This is an activity that goes on in
spite of your will or desire.
• Perception, however, is not
objective and unlearned; it is
context and culturally dependent
and directed towards making
sense of the world.
• Complete the exercise on page 46
• In contrast to this exercise, have
you ever seen a movie where you
recognize an actor but can seem
to place who they are?
Sense Perception as an Active
Process
• According to common sense realism,
perception is passive and a relatively
straight forward process giving us an
accurate picture of reality.
• But there is more to perception than meets
the eye, and it is active process not a
passive one.
• Rather than just relying on what’s ‘out
there’ our perception is affected by the
structure of our sense organs and our
minds.
• Watch: “How The Human Eye Works”
• Complete Reuben Abel Reading with
questions
Interpreting Our World
• Although it seems easy for us to perceive the
world, perception is actually a very complex
process.
• Our perception is broken down into:
– Sensation – what we perceive in the world
– Interpretation – what our minds do with it
• Read: Visual Agnosia: A World Without Patterns,
Faces Without Meaning by Hillary Lawson
• Watch: My Strange Brain and At First Sight
• We usually are not aware of how we interpret the
world, we just experience the world of our
perceptions, but maybe by looking at the world of
perceptual illusions we can help to move beyond
sensations and examine our interpretations.
Organizing Our World
• The mind organizes things the following
way:
• Attraction of a stimulus – you pay
attention
• Differentiation of stimulus – a figure
versus a background relationship
• Focus on stimulus – the details of the
thing
• Naming the stimulus – closure
• What are some examples of things we
would like quick closure in our
perception and renewable closure?
The Gestalt Principle
• Gestaltists find that the mind perceives the
simplest possible form but also that it tends to
see the best or most correct possible form.
• This means that we tend to see things not as
they really are but as our minds think they
should be. We make mental corrections all the
time.
• The fact that our brain interpret new stimuli
based on past experience is critical to our
being able to use perception as a way of
knowing.
We perceive whole configurations not
parts. As you read, you read words not
letters.
Look at the chart and say the
colour NOT the word
Inattentional Blindness
• Watch: The Awareness Test
• Read the quote by Alva Noe
• ...consider the following familiar sort of gag. I say to you as you tuck into
your lunch: ‘Hey isn’t that Mick Jagger over there?’ You turn around to
look. When you do, I snatch one of your French fries. When you turn
back you’re none the wiser. You don’t remember the exact number or
layout of fries on your plate and you weren’t paying attention when the
fry was snatched. Your attention was directed elsewhere.
• It turns out that this sort of failure to notice change is a pervasive
feature of our visual lives. Usually when changes occur before us, we
notice them because our attention is grabbed by the flickers of
movement associated with the change. But if we are prevented from
noticing the flicker of movement when the change occurs, we may fail
to notice the change. What is striking – and this will become important
later on – is the fact that we will frequently fail to notice changes even
when the changes are fully open to view. Even when we are looking
right at the change when it occurs, something we can test with eye
trackers, we may fail to see the change.
Inattentional Blindness
• Perception is attention dependent. You only see
that to which you attend.
• The video clip you watched was an example of
inattentional blindness
• Changes that affect the meaning of any scene are
more likely to be noticed; other changes are
ignored
• Our brain does not build up detailed internal
models of the scene even though we think this is
the case
Additional Thoughts about Perception
and Meaning
• So we don’t notice things. Maybe that isn’t the
purpose of perception. For example, study of visual
perception reveals that perceptual processes are not
structured to record data but to organize meaning.
• And maybe this isn’t a weakness at all. Image if we had
to record and maintain all data as separate fragments;
we would become paralysed from dealing with a chaos
of inputs with nothing connected to anything else.
• The miracle of the mind is that it copes so well with a
jumble of inputs and is able to organize sense data so
that most of the time your world is reasonable
coherent, predictable and stable.
Making sense of the disorderly array of
stimuli that constantly bombard us
• We filter out much of what reaches us. We only
pay attention to certain things. We stop paying
close attention to something as soon as it
becomes familiar, or as soon as we can classify it
with a word.
• We rely on memory to ‘fill in the gaps’. This
capacity is beneficial to our individual and
collective survival.
• If we had to process all the stimuli that reach our
sense organs all the time, our brains would be
too busy to become aware of the...
HUGE GRIZZLY BEAR STALKING US!!!!!!
Making sense of the disorderly array of
stimuli that constantly bombard us
• Head out into the hallways of the school. As you walk around,
try to empty your mind of everything you’ve ever learned about
your environment. Try to react immediately to everything solely
with your sense perceptions, without classifying or judging
anything.
• Look at a door and don’t think ‘door’, enter a classroom and
don’t think ‘classroom’, let only your senses react to your
classmates and teacher. Put food in your mouth and don’t
identify the food, classify its taste with a word or think of its
nutritional value.
• What would the world be like if we only relied on our sense
perceptions?
• How do we make sense out of our world?
• Complete the description of the teacher activity.
Selectivity of Perception
• What we perceive out of all the ‘sense noise’
of the environment depends on a host of
factors about the object of perception, the
person who is perceiving, and the context in
which the perception is taking place.
• Many factors influence what we perceive and
remember: out of all possible sense
observations that we might make, we catch
only a few, and out of all that we might
remember, we recall even fewer. Perception is
a selective process.
Selectivity of Perception
• Apart from visual illusions, another reason for
being cautious about what our senses tell us is
that perception is selective
• A vast amount of data is constantly flooding in
to our senses, and our minds would overload if
we were consciously aware of everything
• So we only notice some things in our perceptual
field and overlook others
• Certain aspects of a situation engage our
attention and ‘stand out’, and the rest fade
away into a more or less indeterminate
background
Selectivity of Perception
•
•
•
•
•
If we ask what kind of stimuli we usually notice,
intensity and contrast are two important factors
A ticking clock may go unheard, but a bomb
exploding in the next classroom would
What you see also depends on various
subjective factors such as interest and mood
Your interest can be thought of as filters which
determines what shows up as you scan the
world around you
As the pattern of our interest changes, so does
what we perceive
Selectivity of Perception
•
•
•
•
When your family buys a new car, you might
notice the same brand of car everywhere
When a woman becomes pregnant, she often
begins noticing pregnant woman wherever she
goes
Our feelings and emotions also effect our
perceptions – when you are in a good mood,
you see the world in a different way to when
you are in a bad mood
An emotion such as love can have a strong
effect on perception
Selectivity of Perception
•
•
•
When in love with someone, you may
unconsciously project your dreams onto them
so that they seem to possess every quality you
desire
And, when you fall out of love with someone,
you may look at your ‘ex’ and wonder what you
ever saw in them
It has been said that in the beginning of a
relationship, you tend to notice the things you
have in common, and at the end of a
relationship we tend to notice the things that
make us different
The Impact of Culture on Perception
• Complete The
Allegory of the
Cave/The Matrix
activity
• Complete the
Culture Simulation
Game
Perception, Conception and the Influence of Culture
•Do all of the
students pictured
here perceive cows
and bulls in a similar
way?
•Yes, they all use
their senses and
believe they do so
within the normal
range.
•Their sense
perceptions of the
animals are similar,
but their conceptions
– shaped by prior
learning including
cultural practices and
beliefs – differ
considerable.
We Perceive Things or People
Differently Based on the Name
•Depending on the name given
to those in this photo, what
would be the chance of
someone investing in their
company?
•Imagine they were called :
The Young Inventors, The
Geeks from the Blue or
Microsoft Executives. What
would be your interpretation
of the photo without a
caption?
•This is a picture of the
Microsoft Executive in
1978...Bill Gates is in the lower
left corner.
The Myth of the Mental Instant Replay
• We think of visual perception as operating like a television
camera, recording the full details of a scene on a tape that is
labelled and filed in the brain.
• Several studies demonstrate that our ability to recall is
shockingly vulnerable to manipulation by emotion, social
stresses and position or the way a question is asked among
other factors.
• Complete Perception and Multiple Perspectives Exercise
• You will be given a card. On it, you will find a witness or a
person connected to the following event involving a car
accident.
• Consider the various perspectives and the various meaning
that each perspective brings to the interpretation of the
event.
• What kinds of questions would you ask of those involved?
What would you expect to be asked?
Distinguishing Appearance from Reality
• The fallibility of perception has implications in
the real world as well
• In criminal trials, juries tend to put a great deal
of faith in eye-witness testimonies, and this
evidence can be a major factor in determining if
someone is guilty or innocent
• However, according to psychologists, the
uncorroborated evidence of a single witness
should be treated with great caution – and
many instances of criminal convictions based on
eye witness testimony have turned out to be
false
Distinguishing Appearance from Reality
• Although perception is an important source of
knowledge, our distinction has shown there are at
least three reasons for treating it with caution:
– We may misinterpret what wee see
– We may fail to notice something
– We may misremember what we have seen
• However, we should not be overly sceptical and
never trust our senses, we need a way to
distinguish appearance from reality
• Confirmation by another sense: is one way to do
this – for example, if something looks like an apple,
and tastes like an apple – then it is reasonable to
assume it is an apple
Distinguishing Appearance from Reality
• Coherence: is another way to distinguish
appearance from reality
• If what you see doesn’t ‘fit in’ with your overall
experience of the world, then you might be
mistaken
• If you were drinking and saw a pig flying over
some rooftops, you might be unlikely to believe
the next day in what you saw because your
experience has shown that pigs lack the
aerodynamic abilities to fly – so you will dismiss
what you ‘saw’ as an alcohol induced
hallucination
• Coherence also explains that the pencil was not
bent due to our experience with pencils
•
What is Really Out There?
If our eyes had evolved differently, and we were sensitive to
light at a different wavelength we would not see white in the
snow at all
• We must conclude that their in no color in the world at all –
reality is colorless
• The tree in the forest: is a well known question “if a tree falls
in the forest and there is no one around to hear it – does it
make a sound?” – the common answer is yes, of course it
makes a sound!
• One way to resolve this is to classify two types of sound:
– Physical sound – the air molecules vibrating into waves of
sound
– Experienced sound – the actual crash and bang we hear
when the tree hits the ground
•
•
•
•
•
•
•
What is Really Out There?
In another example, when you drink coke, it tastes
sweet
Does the sweetness exist in the coke, or in your mouth?
Again it is a subjective experience that results from the
coke and your taste buds
While it may be easy to accept that taste and pain are
subjective experiences, it might be harder to grasp this
about things like colors
Surely, the sky is blue and snow is white?
But if we apply the same logic, we are forced to admit
that the white is no more in the snow as the sweetness
was in the coke
The white we see is the interaction of our eye
mechanics to the wavelengths of light reflected by the
snow
Theories of Reality
• There are three different theories about the
relationship between perception and reality:
• Common-sense realism: is the common-sense idea,
that the way we perceive the world mirrors the
way the world is
• However, since what we perceive is determined in
part by the nature of our sense organs, we have
seen that there is good reasons for rejecting
common-sense realism
• Scientific realism: in which the world exists as an
independent reality, but is very different from the
way we perceive it
Theories of Reality
• In scientific realism, a table is mostly emptiness,
sparsely scattered in the emptiness are electric
charges rushing around with great speed
• The scientific descriptions of atoms whizzing around in
space seems a far cry from the colors, odours, and
sights of the world
• Phenomenalism: the philosophical position known as
empiricism – and this leads to the more extreme
position of phenomenalism
• According to this view, matter is simply the permanent
possibility of sensation and it makes no sense to say
the world exists independent of our experience of it
Theories of Reality
•
•
•
•
Using our table analogy, a phenomenalist would say
that if you go into our classroom you would have ‘table
experiences’
Phenomenalism follows the logic that all knowledge
must ultimately be based on experience
It says that we cannot know what the world is
independent of our experience of it – the point is
beyond our experience of reality, there is nothing to be
said
It is a somewhat humble position, for it insists we know
the world from our distinctly human perspective and
have no right to pontificate about the nature of
ultimate reality
What Should We Believe?
•
The three theories of reality can be summarised as:
– Common-sense realism – “You see is what is there”
– Scientific realism – “Atoms in the void”
– Phenomenalism – “To be is to be perceived”
• What is interesting is that if you push imperialism to its
limits – you come up with counter-intuitive conclusions
• So we choose empiricism and insist we know nothing
about ultimate reality or reject empiricism and insist
there is a world independent of our experience of it
• Most people tend to be realists about the world,
despite its doubts
What Should We Believe?
•
•
•
•
•
So to conclude, perception is an important way of
knowing and plays a key role in most areas of
knowledge
However, as we have seen through the unit, there is
more to perception than ‘meets the eye’
We cannot just take our sense evidence for granted as
our senses can deceive us, they can be selective, and
distorted by our beliefs, prejudges, and emotions
So perception cannot give us certainty, but as we have
previously discussed, knowledge requires less than
certainty
If perceptual evidence is consistent with other ways of
knowing like reason, then it is a good foundation for
reliable knowledge