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 - helps us make sense of the world
- So, seeing is not necessarily believing. Here's why:
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 gree material, and lit by red light,
people will often perceive the cutouts as green trees and gray donkeys.
- You can have left brain/right brain conflict when reading words that are a certain color. Try it yourself!
- 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 throughout 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.
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
- 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
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 - 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
- Man in the shadows - Do you ever feel as though someone is
- UFOs - we try to make something familiar out of a vague
- 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.
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, if any.
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
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.