What

1
Whats the difference between sensation and
perception?
2
Do We have 5 senses?

• Sight
• Hearing
• Taste
• Touch
• Smell
• What about temperature? Balance? Movement?

3
How does it work?

• Sense receptors (specialized cells some in the
  ears, some in the eyes, some on the tongue) FIRE
  to stimulate sensory NEURONS which stimulate
  specialized paths to specialized areas of the
  brain (visual cortex, auditory cortex, etc) so.

Sense receptors convert physical energy (touch,
heat, light) to electrical energy
4
How does it work?

• if we could stimulate the visual cortex of a
  blind person, would they be able to see?
• Well probably, yes.
• Ptito (2005) connects pattern detector to
  electrodes on tongue which stimulate visual areas
  of brain.

5
Synesthesia

• Something similar happens naturally to some
  people.
• Sounds have taste or color.
• Colors have scents or tastes.
• One synesthete who attended an orchestra concert
  as a child thought the lights were lowered so the
  audience could see the colors better!!!!!!!!!

A fun and interesting paper topic!!
6
Can you believe everything you see? Do you see
everything there is to see?

• No, and no.
• Visible light we see only certain ranges of
  wavelength
• Audible sound other animals hear much different
  ranges of pitch
• We build perceptions from our sensations.

7
How do we perceive waves?
Vision Sound Wave
Hue. What color is it? Shorter blues Longer Reds Pitch. What note is it? C or D or G? Length (frequency)
Brightness How much light does it reflect? Yellow is a bright color Loudness. Height (amplitude)
Saturation just one wavelength pure bold mixture pale (white is a mixture of all wavelengths) Timbre. Flute (pure) or electronic tone vs acoustic guitar or oboe. Complexity (do the wavelengths vary? How much?)
8
From the eye to seeing
Retina Back of the eye location of visual
sense receptors. Lens reflects images upside down
onto the retina Rods Sensitive, but not to
color concentrated in the periphery Cones
Sense color concentrated in the center of the eye
9
Structures of the retina
chapter 6
10
From the eye to seeing
Once in the cortex, we construct what were
seeing. A few years ago, neurologists
demonstrated the existence of a Halle Berry
neuron. Many years ago, Huble Wiesel (1968)
paved the way for this work showing that
particular cells they termed feature detectors
fired for particular patterns, such as a line at
a particular angle.
11
Gestalt principles
chapter 6

• Proximity
• Things close to one another are grouped together
• Closure
• The brain tends to fill in gaps to perceive
  complete forms

12
Gestalt principles
chapter 6

• Similarity
• Things that are alike are perceived together
• Continuity
• Seeing continuity in lines that could be
  interpreted as either continuous or abruptly
  shifting in direction.

13
Depth and distance perception
chapter 6

• Binocular cues visual cues that require the use
  of both eyes
• Convergence
• Turning inward of the eyes, which occurs when
  they focus on a nearby object
• Retinal disparity
• The slight difference in lateral separation
  between two objects as seen by the right and left
  eyes

14
Depth and distance perception
chapter 6

• Monocular cues visual cues that require just one
  eye
• Interposition If you are blocking my view of the
  car, you must be closer
• Linear perspective We are fooled by this in the
  Muller-Lyer Illusion
• Size constancy Why does the moon appear so much
  larger when its near the horizon?

15
The Müller-Lyer illusion
chapter 6
16
Visual constancies
chapter 6

• The accurate perception of objects as stable or
  unchanged despite changes in the sensory patterns
  they produce
• Shape constancy A pie is always round even when
  its an arc on the retina
• Location constancy We see objects as still even
  though their image on the retina moves as we move
• Size constancy We see objects as staying the
  same size even though they grow smaller on the
  retina
• Brightness constancy We see snow as white on a
  cloudy day when the waves amplitude may send a
  different message
• Color constancy We see an objects color as the
  same in different light, even though the
  reflected wavelength changes

17
How do we hear?

• Remember sense receptors translate physical
  (sound waves) to electrical (neural impulse)
• Ear drum? No.
• Hammer, anvil, stirrup bones? No.
• All the way inside the cochlea hair cells.
• NOTE! These are VERY fragile cells. Your MP3
  player, your job, or one concert could all cause
  permanent hearing loss.

18
How do we hear?

• Gestalt principles apply to hearing, too
• Proximity
• Continuity
• Similarity
• All help us know what sounds go together, and
  which sounds are the background noise

19
Taste

• How might taste help us survive?
• Sweet
• Sour
• Bitter
• Salty
• Umami(?!)

20
Taste

• Where are the sense receptors for taste?
• Inside the papillae (you can see these on your
  tongue) inside the taste buds
• How many taste buds do you have?
• 500 for some people
• 10,000 for others
• Who has more? The person who loves jalapenos or
  the person who cries when they get one?

21
Is there a connection between smell and taste?

• Many foods (chocolate, for one!) have almost no
  distinguishable taste without smell.
• Smell is a much more sensitive sense.
• Specialized cells sense receptors millions of
  them and there are about 1,000 different types!
  Each responds to a different part of a molecules
  structure.

22
Can you think of a category or type of smell?

• We have salty, sweet, bitter, etc for taste. What
  about smell?

23
Where does pain come from? Where does it go? Is
pain a sense?

• Sometimes we feel pain where there is no damage
• Sometimes there is damage where we feel no pain
• Sometimes we feel pain where there is nothing at
  all
• Do we feel only the pain we need to feel?

24
Where does pain come from? Where does it go?

• Multiple sets of neurons are involved in
  inhibiting or allowing pain signals to travel to
  the brain
• The brain sometimes sends its own messages to
  these neurons
• What might be the benefit to the brain of
  controlling pain?

25
One more sense for now

• Sometimes pain comes from within the body
• Kinesthesis always comes from inside the body
• What messages do you need from your body in order
  to walk?
• Semicircular canals in the ear provide
  information for equilibrium our sense of
  balance
• Other info you need?

26
How do our perceptual tricks develop?

• Both inborn and learned
• Feature detector cells can lose their
  functionality if they are not used (Blakemore
  Coopers 1970 study of cats)
• Infants wont cross visual cliff at 6 months,
  and seem to notice the difference at 2 months
• If vision or hearing are restored to a blind or
  deaf person after infancy, perceptual skills
  develop only to a limited degree (critical
  periods for experience to create learning)

27
Are our perceptual tricks universal? More
evidence of learning

• Experience What is common in your environment
• Needs/desires Hungry? Youll be the first to see
  the picture of food
• Beliefs UFO sightings, Mother Theresa french
  toast
• Emotions Influence pain perception among others
  (what do you see in the dark when youre afraid?)
• Expectations Where is the typo in ths sentence?
• All influence what we see

28
Can you perceive without sensing?

• What if a picture is flashed too quickly for you
  to see it? Image can influence opinions/memory
• What if you are asleep and listening to a Learn
  to Relax or Improve Your Memory tape? Placebo
  effect! Whichever tape you think youre listening
  to, that is the skill that will improve.
• ESP? Many, many efforts to demonstrate
  well-designed studies fail. (Poorly designed
  studies succeed.) Remember the influence of
  beliefs and expectations? These probably explain
  most incidents of ESP.