Why Does It Matter?
Our normal perceptions do not correspond directly to reality. The things that we percieve (see,
hear, smell etc.) are not entirely determined by what our senses detect. Our perceptions are
also determined by what we expect, what we know, what we believe.
-
Our perceptions are not photographs, they are
constructions - something that our minds manufacture.
-
What we perceive is partially determined by what we know or believe.
-
Constructive perception has survival value - it helps us make sense of the world.
-
So, seeing is not necessarily believing. Here's why:
Perceptual Constancies
Our tendency to have perceptual experiences in the absence of stimuli
-
Color constancy
-
We often perceive an object to be a color because we expect it to be a certain color.
EXAMPLE: If you have a cutout or a tree and a donkey both made from green material, and
lit by red light, people will often perceive the cutouts as green trees and gray
donkeys.
-
We also perceive color sometimes when it is physically impossible. EXAMPLE: The vision
cells in the center of the retina are the only ones that can see color. Therefore, we
should only see color in the center of our visual field. Objects in our peripheral
vision should not appear in color. But we see color through the field. Why? Color
constancy! Try looking at colored objects with your peripheral vision - what do you see?
-
Size constancy - learned perception (does a truck driving in the distance get smaller?)
-
You percieve the size of familiar objects (like a truck) to be the same size no matter
how far away they are because you know that distance doesn't change the size of an
object. However, the size of the image on your retina shrinks as an object moves away
from you.
-
There is a tribe called the Ba Mbuti that provide evidence that size constancy is
learned. This tribe lives in a thick jungle where they never are able to see more than a
few yards away. When taken into a field and shown Buffalo in the distance, they asked
what kind of insects they were. When told that the animals were buffalo, the
tribespeople thought it was witchcraft.
Expectation
We perceive what we expect to perceive
-
Flashing light experiment- subjects were told to walk down a hall and stop walking when they
saw a light flash. Many subjects stopped walking despite the fact that no flash was given.
They simply expected a flash and believed they saw one. Similar experiments have shown
subjects who could feel warmth, smell an odor, or feel an electric shock because they
expected to.
-
We have all experienced such hallucinations. Have you ever seen the hands on a clock move
only to find out that the clock didn't run? Have you ever heard the phone ring when you were
in the shower, but later found it had not rung at all?
-
What other experiences have you had that may have been due to expectation?
Looking for Clarity in Vagueness
When our senses are confronted with a formless stimulus, we often perceive something distinct.
We look at clouds, smoke, fuzzy paintings and see shapes that are familiar. This illusion is
called pareidolia. Many cases of pareidolia are common:
-
Man in the Moon - a cultural example
-
Samoans see a woman weaving
-
Chinese see a monkey pounding rice
-
East Indians see a rabbit
-
Jesus' image in a tortilla - famous case of a housewife in New Mexico who found the shape in
the skillet burns and took it as a sign of Christ's second coming.
-
Messages in rock music played backwards
-
Man in the shadows - Do you ever feel as though someone is following you?
-
UFOs - we try to make something familiar out of a vague object.
-
The Blondlot Case and N-rays - famous case in which scientist Rene Blondlot announced the discovery of N-rays, which
could be detected by the human eye and were emitted by metals. They apparently increased the
brightness. Blondlot claimed that this type of radiation was blocked by lead. Scientists
could not reproduce his results because the experiments were entirely subjective. Another
scientist named Wood challenged Blondlot while participating in a test of N-rays. He told
Blondlot that a lead sheet was in place when it was not, and Blondlot claimed to see the
rays. Wood then placed the lead sheet in front of the source of N-rays and Blondlot claimed
to see the N-rays. Blondlot's observations depended entirely on his beliefs, and were not
correlated to when the sheet was actually in place.
Memory
Our memories are consturctive, not literal.
Imagine a scene...How do you look at it? Recall a scene - do you look at it through your own
eyes?
Car accident film - hit vs. smash and long term memory - if people watch a car accident on film
and are asked a question after viewing the scene, the wording of the question affects how the
subject remembers the scene. When asked "How fast were the cars going when they smashed?",
subjects reported faster speeds when asked about it again later than subjects who were asked,
"How fast were the cars going when they hit?"
Selective memory - Dreams, we have over 250 a night but only remember a few of them.
Judging
We can lead ourselves to believe that something is paranormal or supernatural when it actually
isn't.
Have you ever had a friend call just when you were thinking about them? It may seem strange or
paranormal, but there are many more times when you think about someone or something and nothing
related happens.
What are the chances that 2 people out of a party of 23 have the same birthday?
1/2-----1/1000-----1/40----- 1/2020
The answer, surprisingly, is 1 in 2!
How many things happen to you in the course of a day? Incredible pairings are more likely than
you think.
Science is a systematic attempt to get around these limitations. Science tries to remove
personal experience from the scientific process.
Additional Resources
"Shrine of the Miracle Tortilla" http://www.roadsideamerica.com/attract/NMLAKtortilla.html
"Blondlot and N-Rays" http://skepdic.com/blondlot.html