Perception

WOK

Watch – Human Senses: Touch and Vision pts 1-3

Quotes

‘Its not what you look at that matters, it’s what you see.’ Henry David Thoreau 1817-62

‘If the doors of perception were cleansed, everything would appear to man as it is – infinite.’ William Blake 1757-1827

‘Things do not seem the same to those who love and those who hate, nor to those who are angry and those that are calm.’ Aristotle 384-322 BCE

‘A fool sees not the same tree that the wise man sees.’ Chinese Proverb

A show of hands

Remove all your rings and any other external objects on your hands and come with me up to the photocopier

Introduction

Perception can be defined as the awareness of things through our five senses – sight, sound, touch, taste and smell. These are the ‘gates and windows’ of the mind – channels of communication between ourselves and the outside world.

Sight

Sound

Touch

Taste

Smell

If for some reason you had to sacrifice one of your senses, which would you be most willing to lose and which would you be least willing to lose? Give reasons

Could watch – Babel – Nightclub scene (9mins) – What it might be like to be deaf.

Empiricism

The school of philosophy that states all knowledge is ultimately based on perceptual experience.

Perception clearly plays a key role in almost all subject areas, ranging from the sciences through history to the arts. Think for example, of the role played by observation in biology, or eye witness accounts in history, or the ability to see things with new eyes in the visual arts.

Do you think that perception is a more important source of knowledge in some subjects rather than others? Are there any areas of knowledge in which it plays no role?

Common-sense realism

Perception is a passive and relatively straight forward process which gives us an accurate picture of reality

Colours, sounds and smells exist ‘out there’ and the act of observation doesn’t affect what is observed

Our perception of the world is adequate for dealing with the practical demands of everyday life

If our senses were not reliable we would not have survived as a species

However……….. http://www.youtube.com/watch?v=9tr5kQ5ZC90

Perceptual illusions

Perception is more complex than common-sense realism would have us believe

The mind actively (not passively) structures what we perceive and gives what we are experiencing a context, figure and ground, visual group, and expectation.

Context

The way we see something depends partly on the context in which we see it

Figure and Ground

We tend to highlight certain aspects of what we see (figure) and treat other parts as background (ground)

Visual Grouping

We have a tendency to look for meaning in what we see and group our perceptual experiences together into shapes and patterns.

Expectations

Expectations can influence the way we see things

Brain Story

http://www.youtube.com/watch?v=MrAwr-ReuVA

Watch this video clip

Face upside down

Find a partner and face each other upside down. Use a table, the floor or the armchair to get comfortable and then face one another. Keep about 50cms apart and just stare for a while – What happens?

Perspective affects the way we see things

Describe how a tree would be viewed by the following:

1. A biologist2. A Logger3. An

environmentalist4. A native American

Feelings and Emotions

Feelings and emotions shape and colour our perceptions

When you’re in a good mood you see the world in a different way to when you’re in a bad mood

Emotions such as love can have particularly strong affect on our perception

When you’re in love you think the person you’re in love with is the most amazing person on the planet – When you fall out of love with someone, you might wonder what you ever saw in them.

Is the glass half full or half empty?

Appearance from Reality

Perception is an important source of knowledge, however….

1. We may misinterpret what we see 2. We may fail to notice something 3. We may misremember what we

have seen

How then do we distinguish between reality and appearance in everyday life?

Confirmation by another sense Use a second sense to confirm the

evidence of a first. If it looks like an apple and tastes

like an apple, then it seems reasonable to conclude it is an apple.

If there is a conflict of sensory information then touch is always understood to take priority.

The prejudice of touch over other senses is due to the idea that if we are unsure whether the wall in front of us is an illusion – try banging your head into it.

In short, if it hurts then its real

Coherence

A second way of distinguishing between appearance and reality is in terms of coherence.

If you see something that doesn’t ‘fit in’ with your overall experience of the world, then the chances are you are mistaken.

If a drunk sees a flying pig over the roof tops one evening, he is unlikely to believe what he saw when he was sober again.

Coherence also explains why in the pencil example it makes more sense to say that we suffer a visual rather than a tactile illusion.

Independent testimony

The testimony of other people is the final way of distinguishing our view of appearance from reality.

Our own eye witness account of an event cannot always be taken at face value but the credibility of such an evidence is greatly increased if it is confirmed by other people.

If dozens of independent witnesses claim to have seen a plane crash into a building, there is a high – beyond reasonable doubt – probability that such a testimony is true

Summary

Independent testimony

Coherence

Other sensesSummaryAlthough our senses make mistakes, we can correct our mistakes by appealing to a second sense, coherence and the testimony of other people. We can never be truly certain because knowledge requires something less than certainty.

Although fallible, perception in many cases is a reliable enough foundation on which to base our knowledge claims

Perception and the Ultimate Reality

How far can our senses give us knowledge of the ultimate reality?

Psychology of perception Human senses are incredibly limited in

what they can do For example our eyes are sensitive only

to a certain wave length and we cannot see ultra violet and infra red.

Our ears only detect certain kinds of sounds

Our noses certain kinds of smell – Dogs can hear and smell things we are completely unaware of.

Read extract from Virginia Woolf’s Flush p24 TOK Course Companion

Whales communicate to each other using sonar, often at such low frequencies they cannot be heard by humans without special instruments

http://www.youtube.com/watch?v=WabT1L-nN-E&feature=related

Bats

Some animals have senses that are completely different from our own Eg Bats navigate by a system of echo-location giving them what might be called ‘acoustic vision’.

http://www.youtube.com/watch?v=5mwoOyOleGc

Imagine if we had evolved so that our eyes could see ultra violet and infra red, or that we could use echo-location -

Heightened sensory awareness

Watch the clip – The boy who could see with no eyes.

Or Read p26 TOK Course companion – The case of Cristina Frias

Discuss

What is really out there?

If our eyes had evolved differently and were sensitive to light of a different wavelength everything would appear different to us Eg Grass wouldn’t be green

The world has no colour at all Reality is colourless

Our sense receptors and sensations are particularly human and our interpretation of sensation is likewise dependent on our brains. It seems to us, as we see the pinkness and sweetness are in the roses and the honey rather than in their effect upon us. Yet our conscious experience of honey are the product of the electoral and chemical organisation of our brains.

‘Our conscious world,’ declares one bio-psychologist ‘is a grand illusion’.

The tree in the forest

In groups try to answer this question – ‘If a tree falls in a forest and there is no one there to hear it, does it make a sound?’

After having discussed this it seems plausible to conclude ‘nothing can be said to exist independent of our experience of it’.

In the words of G. Berkeley ‘to be, is to be perceived.’

Theories of Reality

1. Common – sense realism

2. Scientific realism

3. Phenomenalism

Common-sense realism

Mentioned at the beginning of the slideshow

The way we perceive the world mirrors the way the world is

However, since what we perceive is determined in part by our sense-organs, we can see that there are good reasons for rejecting common-sense realism

Scientific-realism

The world exists as an independent reality but is very different from the way we perceive it

According to a common sense description of a table it will have extension and colour, and is comparatively permanent and substantial. But the scientific table is quite different:

Consider Sir Arthur Eddington’s description of a table ‘My scientific table is mostly emptiness. Sparsely scattered in that emptiness are numerous electrical charges rushing about with great speed; but their combined bulk amounts to less than a billionth of the bulk of the table itself. ‘

The scientific picture draws attention to the strangeness of reality. The familiar, comfortable, sensuous world of our everyday experience vanishes and is replaced by colourless, soundless, odourless realm of atoms whizzing around in empty space.

Phenomenalism

Matter is simply the ‘permanent possibility of sensation’

It makes no sense to say the world exists independent of our experience of it

George Berkeley ‘to be is to be perceived’ Despite its counter intuitive nature phenomenalism

seems to follow logically from the idea that all knowledge must ultimately be based on experience. For if this is true, then we obviously cannot know what the world is like independent of our experience of it

That does not mean the world does not exist independent of our experience of it

But beyond our experience of reality, there is simply nothing to be said

We can only know the world through our distinctly human perspective and have no right to pontificate about the nature of ultimate reality

http://www.youtube.com/watch?v=VZXfqW13Lcg

In short

What should we believe?

Common-sense realism – ‘what you see is what is there’

Scientific realism – ‘Atoms in the void’

Phenomenalism – ‘To be is to be perceived’

Conclusion

Perception is a very important way of knowing which plays a key role in most areas of knowledge. However, we cannot simply take the evidence of our senses for granted. Not only do they deceive us but they are selective and can be distorted by our beliefs and prejudices. In everyday life, there are ways of distinguishing between appearance and reality by using a second sense to back up the first, or appeal to the testimony of other people.

On a practical we cannot ignore our senses. If you want to cross the road, it pays to go with the hypothesis that if something looks and sounds like a truck hurtling towards you then it really is a truck.

Perception cannot give us certainty but as we have seen knowledge requires something less than certainty.

If perceptual evidence is consistent with other ways of knowing such as reason and intuition, then it is probably a good enough foundation for reliable knowledge

The Arts – To what extent do the arts help us to see the world with new eyes?

Emotion – How does your mood affect your perception of things?

Natural Sciences – How far do expectations influence observations?

History – Should we trust eye witness accounts?

Language – How does the way we describe something affect the way we see it?

Religion – Religious experience and search for ultimate reality

Perception

Linking Questions