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Sensation & Perception
Sensation: your window to the world
Perception: interpreting what comes in
your window
Sensation & Perception
• Sensation: taking in
information from
environment
• Perception: how we
organize & interpret
sensory information
– allows us to recognize
meaningful events,
objects…
The Senses
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Vision
Hearing
Taste
Touch
Smell
Vestibular
Kinesthesis
Ladies,
you are
welcome
Vision
• Our most dominating
sense
• Electromagnetic energy
hits our eyes but we
perceive it to be color
• We only see a sliver of
the spectrum of
electromagnetic
radiation
Step 1: Light in the Eye
• Light enters the eye through the Cornea
– protects the eye (think plastic cover over
camera)
• The amount of light that enters is controlled
by the Pupil
– opens and closes like a camera shutter
• Pupil is surrounded by the Iris
– a ring of colored muscle that dialates/constricts
in response to light intensity
– Fun fact: each iris is distinct (scans?)
• Lens is behind the pupil that focuses
incoming light rays into an image on the
retina
• Accommodation: the process of the lens
changing the shape
The Retina
• Retina: where the processing visual info begins (located
at back)
• Rods: receptor cells that detect black, white, gray,
• peripheral vision, strong in dim light
• Bats, rats, mice…
• Cones: receptor cells that detect fine detail & color
• Fovea: retina’s area of central focus
– Cones cluster around fovea
– Responsible for your detailed vision (driving,
reading…)
Step 2: Transduction
• Transduction: the transforming
of stimulus energies (like sights,
sounds, smells) into neural
impulses our brains can interpret
• Retina sends message to your
brain via the optic nerve
• Rods/cones->
bipolar cells->
ganglion cells-> axons form…
optic nerve->
thalamus->
occipital lobe (visual cortex)
• Optic chiasma: where the
optic nerves cross
Astigmatism
Nearsightedness
Farsightedness
Step 3: In the Brain
• Primary visual cortex in
occipital lobes process info
We have specific cells that see
the lines, motion, curves and
other features of this turkey.
These cells are called feature
detectors.
– Color, movement, depth…at
same time!
– Parallel processing: brain
processes many parts
simultaneously
– Feature Detectors: cells
that pick up edges, lines,
angles, movements…
– Visual Processing: retinal,
feature detection, parallel,
recognition
Color Vision
Two Major Theories
Trichromatic Theory
Three types of cones:
• Red
• Blue
• Green
• These three types of
cones can make millions
of combinations of
colors
• Does not explain
afterimages or color
blindness well
Opponent-Process theory
The sensory receptors
come in pairs.
• Red/Green
• Yellow/Blue
• Black/White
• If one color is
stimulated, the
other is inhibited.
Afterimages
Hearing
Our auditory sense
Parts of the Ear
• Outer Ear: collects & magnifies sounds waves
through the ear canal to the eardrum (tight
membrane that vibrates with the waves)
• Middle Ear: transmits eardrum’s vibrations
through a piston made of 3 tiny bones (hammer,
anvil, & stirrup) to the cochlea (snail shaped tube
in inner ear)
• Inner Ear: incoming vibrations cause the cochlea
to vibrate & jostles the fluid that fills the tube
The Ear
Transduction in the ear
1. Sound waves
– enter ear canal
– hit the eardrum
– hit anvil, hammer, stirrup
– Everything is just vibrating!
2. Cochlea vibrates
– The cochlea is lined with mucus
called basilar membrane which
have hair cells
3. Hair cells vibrate & Organ of Corti
turns vibrations into neural impulses
4. Impulses sent by the auditory nerve
to the thalamus which sends to the
temporal lobe’s auditory cortex
It is all about the vibrations!!!
Pitch Theories
Place Theory and Frequency Theory
Place Theory
• Different
frequencies vibrate
in different places in
the cochlea
• Best explains high
pitches
Frequency Theory
• The entire cochlea
vibrates at a
particular frequency
& sends the same
quality of sound to
the brain
• Best explains low
pitches
Deafness
• Conduction Deafness
– An injury occurs in outer or middle
ear (i.e. eardrum)
• Sensorineural Deafness
– The hair cells or nerves in the
cochlea are damaged
– Diseases & loud noises can cause
this type of deafness
– NO WAY to replace the hairs
– Cochlear implant
• electronic device translates
sounds into electrical signals
send some info about sound to
the brain
• Can restore hearing for most
adults
Touch
• Essential to our development
• Receptors located in our skin
• 4 basic sensations
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–
–
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Pressure
Pain
Warmth
Cold
• Gate Control Theory of Pain
– Spinal cord contains a “gate” that
either blocks pain signals or allows
them to continue to the brain
Kinesthetic Sense
• Sense of position &
movement of your
body parts
• Receptors located in
our muscles and
joints
– Interacts with vision
– Let’s see if this
works!
• Cases of people
losing this ability
Click on this to see the story of
Ian Waterman
Vestibular Sense
• Our sense of balance
& movement
• Our equilibrium is
located in our
semicircular canals
in our inner ears
– Sends messages to
cerebellum at back of
brain
Taste
• Chemical Sense
• 5 Taste Sensations:
– Sweet
– Salty
– Sour
– Bitter
– Umami (savory meaty taste)
• We have bumps on our tongue
called papillae
– Taste buds are located on
the papillae
• Sensory Interaction
– Our senses work together
to interpret the world
around us
– Ex:Smell + texture + taste =
flavor
Smell (Olfaction)
• Oldest sense, chemical
• 5 million receptor cells in
each nasal cavity
• Does not go to thalamus,
is oldest sense linked
directly to brain (limbic
system)
– Smell can trigger
powerful memories &
emotions
• Women have stronger
sense of smell