Sensation & Perception

Bell Activity 3/1/2013
Learning Targets: At the
end of class, you will be
able to-Describe the importance of
sensation and perception
-Define: stimulus, signaldetection theory, Weber’s
-Create an experiment
1.) How do things look the
way they do?
2.) What is this color?
3.) How do we know if
everyone else is seeing
the same color?
4.) How do we know we are
moving and if we are,
where we are going?
Sensation & Perception
School Tour
Write down all of the places that you
went (or think you went).
How do you know that these are the
places you went?
Sensation & Perception
 Sensation:
Occurs when a stimulus
activates a receptor
Ex: Changes in heat, light, sound,
physical pressure, etc.
 Perception:
The organization of sensory
information into meaningful experiences.
Ex: Vision incorporates colors, intensity of
light, distance, etc
Fraser’s Spiral
Now, cover up half of the spiral
So…How do we use
sensation and
perception together to
understand our world?
Combination of senses
and past experiences
Sensation & Perception
 Our
knowledge of the world comes from
chemical & electrical processes occurring
in the brain.
 Stimulus: Any aspect of or change in the
environment to which an organism
A stimulus can be measured by size, duration,
intensity or wavelength.
Sensation & Perception
 Sensation
occurs anytime a stimulus
activates a receptor
 Psychophysicists
study the
relationship between stimuli & sensory
Sensation & Perception
Thresholds, Differences & Ratios
 Absolute
Threshold: minimum amount of
physical energy needed to produce a
sensation 50% of the time.
In general, the senses have very low absolute
Ex: In a dark room, project low-intensity beam of light
against the wall. Slowly increase the intensity of the
light until it can be seen. Then, start with a bright light
and lower it until the participant cannot see it any
Sensation & Perception
Absolute Thresholds of the 5 Senses
Vision: seeing a candle flame 30 miles away on a clear
 Hearing: hearing a watch ticking 20 ft. away.
 Taste: tasting 1 teaspoon of sugar dissolved in 2 gallons
of water.
 Smell: smelling 1 drop of perfume in a 3 room house
 Touch: feeling a bee’s wing falling a distance of 1
centimeter onto your cheek.
*In general, the senses have very low absolute thresholds.
Sensation & Perception
Difference threshold: the just noticeable
difference, minimum amount of energy needed
to produce a change in sensation.
 Sensory experiences depend more on changes
in the stimulus than on size or amount of
stimulus (3lb. into and empty backpack vs. 3 lbs
in a 100 lb. backpack)
 Weber’s Law: The larger or stronger a stimulus,
the larger the change required for an observer to
Sensation & Perception
Sensory Adaptation:
Senses respond to
increases and
decreases in
Example: Eyes
adjusting to darkness
in a room.
Sensation & Perception
Signal Detection
Theory: (Abandons the
idea of a true absolute
threshold) based on the
notion that a stimulus
(signal) must be detected
in the presence of
competing stimuli.
Ex: Being able to study
in a room with a radio
playing and a TV on, etc.
Bell Activity 3/5/2013
Learning Targets: At
the end of class, you
will be able to-Create an experiment
to find absolute
-Describe how vision
1.) What is the
relationship between
sensations and
2.) Eyes adjusting to
light differences is
referred to as ____.
3.) How do 3-D movies
In the Computer Lab
 Go
to Mr. P’s site:
 Click on the “Unit 4” link
 Play the “Eye Hop Game” and take the
“Depth Perception Test.”
 Take the Color Blind Test; From this site,
write down 10 things you learned about
color blindness.
Most studied of all the
How does vision
Light enters
through the pupil &
reaches the lens
that focuses light
on the retina.
The retina contains
two types of receptor
cells: rods and
 Rods and cones are
responsible for
changing light energy
into impulses which
travel along the optic
nerve to the occipital
Cones work best in
daylight and are
sensitive to color.
Rods are used in
night vision
What Happened?
 Answer:
The receptors for green, yellow
and black became fatigued (neuron firing
The Electromagnetic Spectrum: Includes
radio waves, microwaves, infrared radiation,
X-Rays and gamma rays.
 Visible light represents a very small portion
of the spectrum
Binocular Fusion- receiving 2 images but
combining them into 1. We receive two
images from our eyes and form one
composite image of the two views.
Retinal Disparity- differences between the two
images (closing one eye and looking at object).
This is essential to creating our sense of depth
StereopsisPhenomena of
seeing depth as a
result of retinal
When your eyeball is
not perfectly shaped,
your vision will be
impaired because the
focal point has been
 Nearsightedness:
Eyeball is too long
 Farsightedness:
Eyeball is too short
Bell Activity 3/6/2013
Learning Targets: At
the end of class,
you will be able to-Describe the function
of senses such as
taste, touch, smell
and hearing
1.) What are the receptor cells in the
eyes called?
2.) How does retinal disparity help us
with our vision?
3.)What songs remind you of
important events in your life?
4.) What smells do you associate
with childhood?
*Remember only water is allowed
outside of the Commons-School
Depends on vibrations
of the air (sound waves)
that pass through
various bones & fluids
until they reach the
inner ear.
Hair-like cells change
sound vibrations into
neuronal signals that
travel along the
auditory nerve to the
Loudness depends on
the amplitude of
strength/soundpressure is measured in
decibels. (0-14-,
anything over 110 can
Pitch: the experience
associated with a
sound’s frequency: the
“highness” or
“lowness” of a sound.
Hearing-Pathway of Sound
The ear is designed to capture
sound Outer ear receives sounds
 Earflap directs sounds down a
short tube called the auditory
canal to vibrate
 Causes the eardrum to vibrate
Bones in the Middle
Ear pickup vibrations
and push against
Cochlea: Sensory
cells in the cochlea
turn the vibrations into
neuronal impulses
2 Types of Deafness
 Conduction: when
anything hinders
physical motion through
the ear (hearing aides)
 Sensorineural: Damage
to the cochlea (cochlea
Smell and Taste
Chemical Senses:
receptors are sensitive to
chemicals rather than light
or sound.
Smell- molecules enter
nose in vapors, the vapors
come into contact with
smell receptors in nose.
Messages are sent to the
brain by the olfactory
Smell and Taste
Taste- chemical stimulate
receptors (buds) on tongue,
messages sent to brain with
data about texture & temp.
4 primary taste sensations:
sour, salty, bitter & sweet.
6 smell experiences: flowery,
fruity, spicy, resinous, putrid
& burned.
Much of taste is also
produced by smell, temp and
Smell and taste play a much
more important role in “lower
“Hey Bud!” Results
Skin provides brain w/
info. about
environment: pressure,
warmth, cold & pain
Pressure varies from
place to place
(fingertips v. calf) serve
as protection/warning.
Pain makes it possible
to prevent damage
(emergency system)
-Sharp localized pain
immediately after an
-Dull, generalized pain you
feel afterward
-Gate Control Theory of
Pain: You can lesson
pain by shifting attention
-Referred Pain: Pain in area
away from the actual
Balance and Body Senses
Regulated by the vestibular
system (inside inner ear)
 The vestibular system
contains the semicircular
canals with contain
moveable fluid. Over
stimulation can result in
 Sense of movement & body
 Cooperates with the
vestibular system and visual
senses to maintain posture
and balance.
Balance and Body Senses
Without kinesthesis, your movements would
be jerky and uncoordinated.
 Other body sensations come from receptors
that monitor internal body conditions.
 Referred pain-pain in an area that is actually
away from the actual source.
Bell Activity 3/7/2013
Learning Target: At the end
of class, you will be able
to-Find taste locators on the
-Describe the senses
-Explain the Gestalt
Principle of Perception
Remember, water is the only drink
allowed outside of the Commons
area-School Policy!
1.) What serves to
protect the body from
outside harm?
2.) What are the two
types of deafness?
3.) What relays
messages about
smell to the brain?
4.) In your mind, what
do teachers do?
Bell Activity 3/8/2013
Learning Targets: At
the end of class, you
will be able to
-Describe the five
principles of Gestalt
-Describe how we
develop perceptions
-Explain the importance
of subliminal
1.) Which system
regulates our
2.) What are the 2 types
of pain?
3.) What makes our
movements fluid as
opposed to jerky and
*Test on Tuesday!
*Vocab due on Monday.
The process of the
brain receiving
information from the
senses, organizing it
and then interpreting it
into meaningful
Principles of Perception
The brain receives information from
the senses and organizes/interprets
it into meaningful experiences
Gestalt: (whole experience) the
experience that comes from
organizing bits and pieces of
information into meaningful objects
and patterns. The whole is greater
than the sum of parts (ex. music).
If the elements of a pattern are close
to one another or similar they are
perceived as belonging to each
Gestalt Principles: Proximity, Similarity,
Closure, Continuity, Simplicity
5 Principles of Gestalt
Principles of Perception
Perception: The
ability to
between figure
(object) and ground
(background); 3-D v.
Principles of Perception
Perceptual Inference
 Perceptions that are not based on
current sensory information. Otherwise
known as “filling in the gaps”. We use
learned information to help us draw
Often depends upon previous
experiences-but not always (babies
won’t fall off of the “cliff”).
People and animals must be actively
involved in their environments to
develop perception
Learning to Perceive
 Perceiving
is something we learn to do.
 Involvement with one’s environment is
important for accurate perception.
(Ex: Blind patients who gain sight do not know difference between
squares an circles
 Perception
is based on our needs, beliefs,
and expectations. You see what you want
to see.
(Ex: Bias in politics, stereotypes, etc)
Computer Activity
 Go
to Mr. P’s Web Site:
 Click on the Unit 4 link
 Go to the “illusions” and “more illusions”
 Click on the different optical illusions
 Pick 15 of the optical illusions and explain
how they work
Subliminal Perception
Brief auditory or
visual messages
presented below the
absolute threshold
 Ability to detect
stimuli that only affect
the subconscious
 Controversial
Bell Activity 3/11/2013
Learning targets: At
the end of class, you
will be able to-Identify examples of
subliminal messages
-Discuss factors that
shape our perceptions
-Review for the
sensation and
perception test
How would a Psychophysicist
(someone who studies the
relationship between
sensation and perception)
answer the following
If a tree falls in the forest and
no one is around to hear it,
does it make a sound?
Bell Activity Answer
A Psychophysicist would say that the answer is….
Why? From a scientific point of view the physical
event happens (there is sound waves created)
but, the psychological event cannot happen
unless an organism is present to experience the
event (turn sound waves into impulses sent to
the brain to be interpreted)
Subliminal Political Ad?
Subliminal Messages in Fast Food
Other Factors That Shape our
Monocular Depth Cues: Cues that can be detected with
just one eye (bigger=closer)
Binocular Depth Cues: Cues that depend on the
cooperation of both eyes (retinal disparity)
Motion Parallax: Apparent movement of objects in
relation to other objects as you move
Linear Perspective: Parallel lines converge in the
Relative Motion: How other objects move in relation to
your movements
Constancy: We perceive things to be unchanged
regardless of light, distance, angle, etc.