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Unit 3: Sensation and Perception

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Andrew Cantrell

on 19 February 2016

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Transcript of Unit 3: Sensation and Perception

Sensation
Threshold
Sensation
and Perception

Vision
Fraser's Spiral
(cc) photo by Metro Centric on Flickr
(cc) photo by jimmyharris on Flickr
(cc) photo by Metro Centric on Flickr
Every day you are bombarded with stimuli
What is a stimuli?
A
sensation
occurs anytime a stimulus activates one of your receptors sites in a sense organ.

The sense organs detect changes in energy such as heat, light, sound, and physical pressure.
Ex: Skin = heat and pressure
A sensation may be combined with other sensations and your past experience to yield a perception.
A
perception
is the organization of sensory information into meaningful experiences.
Psychologists are still interested in the relationship between stimuli and sensory experience.
Eyes = changes in light
Ears = changes in sound
Fraser's spiral illustrates the difference between sensation and perception. Our perception of this figure is that of a spiral, but it is actually an illusion. Trace a circle carefully. Your finger will always come back to its starting point (you can also find this on page 208 of your textbook).
Psychophysicists try to determine how much of a stimulus is necessary for a person to sense something.
Absolute threshold
- the lowest level of stimulation that a person can consciously detect.
Vision
seeing a candle flame 30 miles away on a clear night
Hearing
hearing a watch ticking 20 feet away
Taste
tasting 1 teaspoon of sugar dissolved in 2 gallons of water
Smelling
smelling 1 drop of perfume in a three room house
Touch
feeling a bee's wing falling a distance of 1 centimeter onto your cheek
difference threshold
- the just noticeable difference (JND) between two stimuli.
Weber's law
- for any change in a stimulus to be detected, a constant proportion of that stimulus must be added or subtracted.
Sensory Adaptation
receptor cells are less responsive to a stimulus that is unchanging.
Without sensory adaptation you would feel the constant pressure of clothes on your body and you would constantly be bombarded with sensory information.
Signal detection theory

- the study of people's tendencies to make correct judgments in detecting the presence of stimuli.
Stroop Effect
Lets start off easily: name the colors as quickly as you can.
Assessment
1. What is the difference between a sensation and a perception?
2.List the five senses and their absolute thresholds.
3. How does the signal detection theory explain how you may be able to study while others are watching television in the same room?
4. Why do you think we do not respond to all stimuli in our enviornment?
5. Who is Gustav Fechner? What is Inner
Psychophysics/Fechner's Wave Theory?
6. Complete all Vocabulary for Section 1.
Vision is the most studied of all the senses. Provides us with information about our environment and objects in it - sizes, shapes, locations of things, their color and distance
So how does it work?
Preattentive process -
a method for extracting information automatically and simultaneously when presented with a stimulus.
Attentive process -
a procedure that considers only one part of the stimuli at a time (Stroop Effect)
Light
L
i
g
h
t
is a form of electromagnetic radiation. These include radio waves, microwaves, infrared radiation, ultraviolet rays, X rays, and gamma rays. Together they are known as the
e
l
e
c
t
r
o
m
a
g
n
e
t
i
c

s
p
e
c
t
r
um
Visible light is a small portion of this spectrum. Each color we see has a different wavelength giving it a different "
c
o
l
o
r
". You can observe the light spectrum by shining light into a prism.
When

some

or

all

of

a

person's

cones

do

not

function

properly,

he

or

she

is

said

to

be
color-deficient.
This

affects

roughly

8%

of

males

and

1%

of

females.

It

is

hereditary
.
Binocular fusion
- the process of combining the images received from the two eyes into a single, fused image.
Retinal disparity
- the differences between the images stimulating each eye. This is essential for 3D depth perception.
Near sightedness - eyeball is too long. You can see things up close but far away they are blurry.
Far sightedness - eyeball is too short. You can see things far away but objects up close seem blurry.
Most sensitive parts: fingertips.
Orietnation and movement of the body to in relation to itself and its parts
Perception
?
What a
re
the Princ
ip
les of Per
ce
ptual Organization?
the experience that comes from organizing
bits
and
pieces
of information into
meaningful wholes
.
Proximity
Similarity
Closure
Continuity
Simplicity
Figure-Ground Perception - the abililty to discriminate between a figure and its background
Perception is learned.
Subliminal perception -
_____ our absolute

threshold.
Depth perception -
ability to recognize distances and three dimensionality - develops in infancy.
Monocular Depth cues
Binocular Depth Cues
Constancy - tendency to perceive certain objects in the same way regardless of chang in angle, distance, or lighting.
perceptions that physical stimuli.
http://www.tumblr.com/tagged/psychotronics
Psychophysics - the study of the relationships between sensory experiences and the physical stimuli that cause them.
?
What is Sensation
Gustav Fechner
Fechner's Inner Psychophysics
consciousness
Stimulus
Yes
No
Present
Absent
Hit
Miss
Correct
Preattentive Process :)
Try to name the colors of the words as fast as you can.
Your attentive and preattentive processes are interfering with each other.
Well we can consult two sources. The oracle of Nye or the of Oracle of the Blue Guy.
Which would you like to choose first?
The Real you
How you perceive yourself
How you think others perceive you
How others perceive you
How you want to be perceived
S
y
n
e
s
t
h
e
s
i
a
Popular Examples
http://en.wikipedia.org/wiki/List_of_backmasked_messages
(Taste)
Supertasters
-
people with 2 or more times the taste buds than nontasters. More sensitive.
Transduction
turning outside information into neural activity.
transduction occurs within the eye - where neural impulses are created from light waves.
occurs within the nose - created from chemical reactions (gaseous molecules).
occurs within the tongue - created from a chemical reaction
occurs within the ear - neural impulses are created from sound waves
occurs within the skin - created from pressure, pain, and temperature.
Species
Number of Scent Receptors
Humans
5 million
Dachshund
125 million
Fox Terrier
147 million
Beagle
225 million
German Shepherd
225 million
Bloodhound
300 million
Cilia
Olfactory Bulb
Olfactory Nerve
gas molecules enter through nostril
molecules get caught in mucus

they sit there until the nose can process them
Olfaction
Gustation
Taste is actually the combination of gustation and olfaction.
Sweet
Salty
Salty
Sour
Sour
Bitter
The tongue is covered with many little bumps called papillae (tastebuds). They can detect 5 experiences: sweet, sour, salty, savory, & bitter.
These combine with temperature and texture to create flavor.
(Smell)
Pressure
Temperature
Pain
...is the body's early warning system
Gate Control Theory
Signals from all skin receptors have to take the same route up the spinal cord to the brain.
If there are other signals competing with the pain signals, our experience of pain will be less
It's like two people trying to squeeze through a door at the same time
Touch/Haptic Sense
2 types:
sharp localized
dull generalized
Coordination
Kinesthesis
(Proprioception)
Ges
talt:
below
subliminal messages -
brief auditory or visual
messages that are presented below the absolute threshold.
illusions -
misrepresent
Hearing
(Audition)
Sound is measured in decibels. Human range is from zero to 140 dB. Any sound that is painful when you hear it WILL damage your hearing.
1. What are the five basic senses?
2. What is the electromagnetic spectrum and why do we only see only a portion of it?
3. Why can we see steadily and read street signs even though we may be walking or running?
4. Describe Smell, Taste, Touch, and the body senses in your own words. How do these senses work? Be clear and concise.
5. Why is orange juice nasty after you brush your teeth?
Loudness
=
height of

sound waves
Pitch
=
rate or frequency
of a wave's vibration
Ear Drum
Auditory Canal
Hammer
Anvil
Cochlea
Cilia
Timbre
the complexity of the waves
Intensity
Pitch
Characteristics of Sound
Deafness
Cilia
Hammer, Anvil, and/or Stirrup
Auditory Nerve
Occurs as a result of problems with one of 3 areas...
Pinna
Outer Ear
Middle Ear
Inner Ear
Auditory Nerve
Stirrup
Balance
-
the

body's

sense

of

balance is regulated
by the vestibular system (inner ear).
Assessment
Hearing depends on vibrations of the air, called sound waves. Sound waves reach the inner ear and move small hairlike cells back and forth (think wheat waving in the wind). The hair cells change sound vibrations into neural signals that travel through the auditory nerve to the brain.
Conductive
Sensorineural
Mixed
cannot be corrected surgically
can be corrected surgically
combo of the first two
Without sensory adaptation you would constantly be bombarded with sensory information.
Signal detection theory -
the study of people's tendencies to make correct judgments in detecting the presence of stimuli.
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