Transcript Perception
Perception
Psychology 1106
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Introduction
When we talked about sensation we were
concerned with moving from one for of
energy or another to neural energy
Bottom up processing
Perception is top down
Imposing organization on sensation
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Attention
Basically the allocation of perceptual
resources to sensation
Selective attention means that we can
only focus these resources in a limited
way
The Cocktail Party Effect
Lots of stuff going on, you hear lots of stuff,
but only listen to the conversation you are in
Tested with dichotic listening
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Dichotic Listening
Different messages in each ear
Shadow one ear
Can’t even tell the language spoken in the
unattended ear!
If story moves from one ear to another,
you cannot help but follow it
Same with vision! (Becklen and Cervane,
1985)
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Dichotic stuff
Even if not perceived, stimuli can affect
behaviour
Wilson (1979)
Preferred previously herd tunes!
Could NOT identify them
Szostalo (1998)
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Learned contingency they could not identify
Form Perception
How do we tell the difference between an object
and the background
Gestalt psychologists thought we use various
rules
Proximity -> group nearby things together
Similarity -> similar figures are grouped together
Continuity -> smooth continuous patterns
Closure -> we fill in gaps
Connectedness -> perceive spots, lines, areas as a
single unit when connected
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Examples
Proximity
Similarity
Closure
connectedness
Continuity
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Depth Perception
A two dimensional
image is projected on
your retina
Yet, you see in 3 D
What’s up with that?
Somewhat built in
Visual cliff experiments
(Gibson and Walk,
1960
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Binocular cues
Your eyes receive subtly
different information
because they are in
different locations
This retinal disparity
provides a cue as to how
far awy an object is
This is how 3D movies
work
Convergence too, how far
in your eyes are turned,
the angle
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Monocular Cues
Many other cues rely
only on one eye
Relative size
Bigger is closer
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Monocular Cues
Interposition
Something blocking
something else is
closer
Relative clarity
Clearer is closer
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More Monocular Cues
Texture gradient
More detail closer
Relative height
High = far, unless
there is an horizon
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More Monocular Depth Cues
Motion parallax
Faster moving stuff is
closer
Relative brightness
Brighter is closer
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So, even though I have no true threedimensional vision, I can see in ‘#D’
Solely based on monocular cues
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Motion perception
Looming effect
Things seem to be coming at you when they get
bigger
Things seem to be going away from you when
they get smaller
Even in babies
A rapid series of slightly different images
conveys movement
Oddly enough bobbing your head doesn’t convey
motion
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Motion perception
The phi phenomenon illusion does a nice
job of illustrating how motion perception
works
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Perceptual Constancy
A book is perceived as
a book, even when
the retinal image is
radically different
The proximal stimulus
is, in fact very
different
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Size Distance relationships
Small is far away
Probably explains
some illusions
Importance of edges
Experience plays a
role
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Lightness Constancy
Black paper reflects
100 times more light
than white paper, if
the black paper is in
sunlight and the white
is in your room
But, you see the black
paper as darker
Context is everything
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Perceptual constancy
These sort of things happen with other
systems too
Clocks seem to make a tick tock sound
We don’t only organize, we interpret
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THEDOGATEMEAT
(McBurney and Collings, 1984)
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Interpretation
People born blind that gain sight, what
can they do?
Figure ground
Colours
Can’t tell a sphere from a cube!
Most of this work had poor control, so
monkeys and cats have been used too
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Interpretation and Experience
Same results with cats and monkeys
Perceptually restricted kittens
Horizontal or vertical bars
Can’t see what they haven’t experienced!
Probably a critical period
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Perceptual adaptation
When you put prisms on people that shift
the world say 45 degrees to the right,
people adapt pretty quickly
Even upside down!
Stratton (1896)
Got sick
Got confused
B day 8 he was riding a bike!
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adaptation
Once he went back to normal he had to re
adapt!
Different depending on species
Cats people, monkeys, no probs
Fish, amphibians, not a chance
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Perceptual Set
When we perceive something we are, in
essence, organizing it
People only notice backwards messages when
you tell them what they are looking for!
Schemas are important
Kids see faces as the key
Adults add the importance of the body
May even explain some stereotypes
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Perception without sensation or
ESP!!!
Remember, science is skeptical
Burden of proof is on the claimer
Keep in mind the idea of chance
Psychics missed the following:
WWII
9/11
OJ
Kennedy assassination
Shuttle disaster
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What psychics did predict…
Satan would be discovered working in a homeless
shelter, reading to the blind and delivering Meals on
Wheels
The Super Bowl would be cancelled after the first half
because team owners would refuse to cough up an extra
$10,000 for each player.
A time tunnel would be created to allow people to make
a one-way trip back into time. (A way to make the return
trip is supposed to be discovered in 2006.)
Source, Jan 8, 2002 issue of ‘The Star’
By definition you CANNOT have ESP
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