Perception as a Way of Knowing

Perception as a Way of Knowing Hwa Chong Institution EL Strand One 2012 Prepared by Mrs Jenny Wong

Perception as a Way of Knowing “Did you ever wonder if the person in the puddle is real, and you're just a reflection of him?" ~Calvin and Hobbes "How do we know that the sky is not green and we are all colour-blind?" ~Author Unknown

Perception as a Way of Knowing

Perception as a Way of Knowing Empiricism is a theory of knowledge that asserts ALL knowledge is ultimately based on perceptual experience. Aristotle But if life itself is good and pleasant (...) and if one who sees is conscious that he sees, one who hears that he hears, one who walks that he walks and similarly for all the other human activities there is a faculty that is conscious of their exercise, so that whenever we perceive, we are conscious that we perceive, and whenever we think, we are conscious that we think, and to be conscious that we are perceiving or thinking is to be conscious that we exist...

Perception as a Way of Knowing Empiricism is a theory of knowledge that asserts ALL knowledge is ultimately based on perceptual experience. Philosophers associated with empiricism John Locke David Hume Leonardo Da Vinci once said, "All our knowledge has its origins in our perceptions.” George Berkeley (UC Berkeley named after him)

Aims and Objectives • By the end of this lecture, students will • be able to understand why perception is an active not a passive process, and the implications this has for our view of the world; • be aware of the often unnoticed role that reason plays in interpreting our sensory information; • be able to discuss the basic philosophical problems with empirical knowledge; • be able to discuss the meaning of the phrase `The mental construction of reality’ ; • be able to notice in everyday life those times when the senses are not reliable; • be able to understand some of the knowledge issues which perception brings up, the limitations of the senses as well as exploring the basic philosophical problems with empirical knowledge.

Perception as a Way of Knowing • We `naturally ’ trust our senses as we generally accept our senses as the bedrock of certainty and reliability. • “ I’ll believe it when I see it.” • “Seeing is believing.” • We even have a word for something ridiculous which we call `non-sense’. • Sense perception is generally described as a physical response of our senses to stimuli.

Perception as a Way of Knowing We perceive the world through our 5 senses (basically). The Science of the Senses: http://www.youtube.com/watch?v=o_tar1s4ZJY

Five Senses? • Bats and dolphins use sonar for navigation. • Homing pigeons and sockeye salmon have deposits of magnetite in their bodies that enable them to detect the earth’s magnetic field to find their way home. • Wolves have very keen sense of smell and eagles have very sharp sight. • What about the case of people with Synaesthesia (being able to smell sounds or hear colours)?

The Sense Organs Seeing and interpreting Anatomy of human eye Anatomy of human smell Anatomy of human ear

Seeing and Believing Consider: If for some reason you had to sacrifice one of your senses, which one would you be most willing to lose and which would you be least willing to lose? Give reason. Think of the role played by your observation • in natural sciences • in accounts in history • in seeing things with new eyes in the visual arts

Is Seeing Believing? • Biology: 19th C claim of an undiscovered planet Vulcan. • History: 1972 `Bloody Sunday’ in Northern Ireland. • Art: Horses drawn eyelashes in the past. The rubber hand illusion: http://www.youtube.com/watch?v=sxwn1w7MJvk

Common-sense realism • Based on common- sense realism, perception is a passive and relatively straightforward process which gives us an accurate picture of reality. Colours, sounds and smells exist out there and the act of observation does not affect what is observed. • But there is more to perception than that. • Perception is actually an active and complex process. Rather than our sense passively reflecting an independent reality, our experience of the world is affected not only by what is out there but also by the structure of our sense organs and our minds

Perception Process The process of sense perception is threefold: • 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... • Finally, higher centres in the brain either ignore or recognise the sensations and their meanings based on neuronal networks of past associations and expectations.

Perception Process Perceptions can be thought of as consisting of two distinct elements: • Sensation provided by the world. • Interpretation provided by our minds. As an important channel communication between ourselves and the outside world, perception’s function and scope should be examined and critically evaluated.

Selectivity of Perception Context

Selectivity of Perception Context: The way we see something tend to depend in part on the surrounding context.

Selectivity of Perception Figure and Ground

Selectivity of Perception Figure and Ground: We tend to highlight certain aspects (figure) of what we see and treat other parts of it as background (ground).

Selectivity of Perception Visual grouping

Selectivity of Perception Visual grouping We tend to look for meaning in what we see and group things into patterns and shapes.

Selectivity of Perception Expectation • Olnysrmatpoelpe can raed this. I cdnuoltblveiee that I cluodaulacltyuesdnatnrd what I was rdanieg. Bacuese of the phaonmnealpweorof the hmuanmnid, aoccdrnig to rscheearch at CmabrigdeUinervtisy, it deosntmttaer in what oredr the ltteers in a word are,theolnyiprmoatnttihng is that the first and last ltteer be in therghitpclae. The rset can be a taotlmses and you can still raeditwouthit a porbelm. This is bcuseae the huamnmniddeos not raederveylteter by istlef, but the word as a wlohe. Amzanig, huh? Yaehand I awlyastghuhotslpeling was ipmorantt!

Selectivity of Perception Expectation

Selectivity of Perception Expectation We tend to see what we expect to see.

Selectivity of Perception Context: The way we see something tend to depend in part on the surrounding context. Figure and ground: We tend to highlight certain aspects (figure) of what we see and treat other parts of it as background (ground). Visual grouping: We tend to look for meaning in what we see and group things into patterns and shapes. Expectation: We tend to see what we expect to see. Therefore, There is an important element of interpretation built into our perception of the world. Perception completely free of interpretation is humanly impossible.

Selectivity of Perception Look at the chart and say the colours, not the words. • Your right brain will try to say the colours but your left brain will insist on reading the words.

Selectivity of Perception • You witness a violent crime. • You get a brief glimpse of the assailant? • How sure are you?

How sure are you?

Perception and Selection We do not sense all the stimuli that we are potentially able to sense. There’s too much going on in our environment for us to handle. We unconsciously ignore many stimuli, otherwise we would not survive as a species. We tend to be more sensitive to stimuli with the following factors: • Intensity • Contrast • Moving

Perception and Selection Subjective factors: • Interest: filters which determine what shows up as you scan the world around you. • Mood: feelings and emotions affect the way we see the world, for example, love and hate. • What we perceive is much affected not just by what is there but by who we are, biologically, personally and culturally.

Is Seeing Believing or Believing Seeing? How much of the `real’ world is in our mind?

Perception as an Obstacle to Knowing Three reasons for caution in relying on perception as a source of knowledge: • We may misinterpret. • We may fail to notice something. • We may misremember what we have seen.

Plato’s Allegory of the Cave The Allegory is related to Plato's Theory of Forms, according to which the "Forms" (or “Ideas”), and not the material world of change known to us through sensation, possess the highest and most fundamental kind of reality. Only knowledge of the “Forms” constitutes real knowledge. Source: Wikipedia Plato’s Argument: http://www.youtube.com/watch?v=N3nYAROx1Xo Plato - The Allegory of the Cave - (The Matrix) Animated : http://www.youtube.com/watch?v=UQfRdl3GTw4&feature=related

Perception and Reality René Descartes Cogito ergo sum: “I think therefore I am.” Philosophy and the Matrix - Descartes http://www.youtube.com/watch?v=lEr8hnvzeHU

Are we then to never trust our senses? • Does knowledge come from the senses and experience or would reason be a more reliable source of knowledge? • Perception: Our day-in and day-out world is real? • Reality: That world is a hoax, an elaborate deception spin by all powerful machines that control us? Matrix: What is Real? http://www.youtube.com/watch?v=WnEYHQ9dscY&feature=related

How do we distinguish between appearance and reality in everyday life? • Confirmation by another sense: Does it look like an apple AND taste like one? Can you see the wall AND touch it? • Coherence : Does it "fit in" with your overall experience of the world? • Independent Testimony: What do other people say? Do they "confirm" your perceptions?

Ultimate Reality • Suppose we evolved sensitivity to a different range of wavelengths, evolved bat-like echolocation, a dog-like sense of smell, an octopus-like ability to alter our skin colour. • What is reality like once we strip away our interpretation and the limits of our sensory apparatus?

What is really out there? Pain • If you burn your hand in a fire, is the pain in your hand or in the fire?

What is really out there? Taste • If you eat an apple pie, it tastes sweet. Does the sweetness exist in the pie or only in your mouth?

What is really out there? Colour • Is the green is no more in the grass as the sweetness was in the pie? • So, if the "green-ness" is merely a result of the ways our eyes are sensitive to light wavelengths and the physical structure of the grass, does this mean, in effect, the world is colourless? • Reality would then be colourless.

Perception as a Way of Knowing