Sensation

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Sensation

• Andy Filipowicz
• AP Psychology Chapter 5 (Myers, 2004)
• Ocean Lakes High School
• Virginia Beach, VA

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Sweet Illusions

• Flash-Lag Effect

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Journal Day 18

• If you had to give up 1 sense, which would you
  least be willing to give up and why? Most
  willing?
• Places to find
• 1) Locker
• 2) Favorite upstairs classroom
• 3) Library
• 4) Baseball Outfield fence
• 5) Mr. Wheelers classroom
• Be back in 10 minutes totalso back at

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Journal 11/9/07

• Whats your favorite color? Why?
• If you could only perceive 3 peoples faces,
  whose would they be and why?
• If you could perceive only 1 type of taste, what
  would it be and why?

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Journal 11/13/07

• Without looking in your notes / book, attempt to
  trace the path of transduction of a sound wave or
  light wave all the way through to the brain
• Use as many parts/names as possible!

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Introduction

• To talk to someone we have to hear what they say
• To catch a ball, we have to see it coming
• How does the external get internalized?
• That in essence, is what sensation is
• Bottom up vs. Top down processing
• Sensation is bottom up
• Perception is top down
• Transduction converting sense signals into
  neural impulses

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How many senses do we have?

• Energy Senses
• Vision light
• Hearing sound waves
• Touch pressure
• Chemical Senses
• Taste
• Smell
• Body Position Balance
• Vestibular
• Kinesthetic

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Basic Principles

• Thresholds We sense some things and not others
• Faintest stimuli Absolute threshold
• Vision single candle flame on a dark night 30
  miles away
• Smell a single drop of perfume in a 3 room house
  
• If stimulus is below conscious awareness, it is
  said to be subliminal
• Difference thresholds or jnds minimum difference
  a person can detect between any two stimuli half
  the time

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• Webers Law the difference threshold is some
  constant proportion depending on the stimulus
• EXAMPLES
• 2 lights must differ in intensity by 8, so if
  you had 100 candles on a birthday cake, how many
  must you add for you to notice a difference?
• Hearing is 5, so if you listened to a 100dB
  tone, at what new dB could you notice a
  difference?
• Take out 3 quartersor 2 different coins
• Place in your shoes!
• Can you tell the difference?
• Applied Psych SalesmanSuit (300) or Sweater
  (75)if you want the customer to buy both, which
  do you show first and why?

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Signal Detection Theory

• When will we detect stimuli?
• Have to filter out the background noise
• Can be internal or external
• Hits vs. misses
• False alarms vs. rejections
• TOP DOWN ideaour expectations truly can alter
  our ability to detect the signals
• ?Who cares? ?What can we test with this?
• Absolute threshold!

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What about subliminal messages?

• What is it?? Subliminal Messages???
• We dont know what the stimulus is, and, it can
  affect our behaviour for a brief period
• Does it make us buy coke?
• NO NO NO NO NO
• Subliminal Messages?
• What about backward maskingdemonic messages in
  various songs?
• Backwards Songs
• Can you think of a movie with subliminal
  messaging?
• The Manchurian Candidate
• The Mind 9 Subliminal Messages

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Sensory adaptation

• Getting used to something (diminishing
  sensitivity to an unchanging stimulus)
• Move your watch up your wrist
• Eyes are always movingif you mechanically keep
  them still, you will notice that things seem to
  disappear
• Hadnout 5-3 (guide ? 8) (Hermann Grid? next
  slide)
• New Hermann Grid
• But, curiously, not as often (13 vs. 910) in
  schizophrenics
• If you stop your eyes from moving, everything
  would go grey!
• Ever notice how everybody elses house smells
  funny and yours has no smell at all?
• Cross-Adaptation (pg7) adaptation to the taste
  of one substance can affect the taste of
  anotherany ideas?
• OJ Toothpaste
• Salt water held in the mouth eventually tastes
  less salty

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Cite Movement Aftereffects (MAEs)

• Stare at this (5-5) while I swirl it
• Does it appear to be receding?
• Cause adaptation of motion-specific detectors
  that are tuned to the direction of the movement
  of the stimuli being viewed
• In a waterfall
• TRIPPY!

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Vision

• Like any sensory process, vision converts some
  energy to neural messages ?term?
• In this case, light
• Light is just a form of electromagnetic radiation
• So are x rays, micro waves, infra red, UV cosmic
  rays etc

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Color

• NOTHING has color itselfrather color is our
  interpretation of reflected wavelengths of light
• So, trees are green because they reflect the
  green wavelength of light they keep in
  everything else
• Amplitude how much energy the light contains
  Brightness (rods)
• Wavelength determines hue (cones)
• Shorter than visible light UV-rays, X-rays
• Longer than visible light infrared,
  microwaves, radio waves
• Colors short to long violet (400nm), indigo,
  blue, green, yellow, orange, and red (700nm) NM
  billionths of a meter

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Fun ? Simultaneous Contrast

• Brightness?
• Brightness x 2
• 3D

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Its a miracle! I can SEE!.

• YOU should know the parts in their functionbe
  able to trace a visual message from light to
  brain
• Wavelength of light determines hue
• Intensity determines brightness
• Light enters the eye through the cornea and the
  pupil
• Pupil size regulated by iris
• Behind pupil, lens, which accommodates (or
  changes its curve)
• Light hits the retina, and specifically the fovea
• Oh ya, it is upside down.

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The Main Parts (pg. 201)

• Cornea transparent protective coating
• Pupil Opening in center of iris (colored part)
  controls amount of light let in
• Lens focuses light (image) onto retina
• Retina lining on back of eye sensitive to
  light contains receptor cells
• Fovea point of central focus on the retina
  (contains only cones)

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Albinism

• There are disorders that can lead to problems for
  the retina
• Albinism its a degreeeveryone has itocular
  albinism is the lack of pigment in the eyes

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Acuity (pg. 202)

• Acuity sharpness
• Acuity is affected by the shape of the eye
• Nearsighted, eye too long, or cornea too curved
  image focused in front of the retina, so far away
  stuff is blurry
• Farsighted, opposite

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The Retina (pg. 203)

• There are two kinds of receptors in the retina,
  rods and cones
• Rods for night, brightness
• Cones for day, color
• When a photon hits a receptor it sends a message
  via the optic nerve to the brain
• Because of this, we have a blind spot!

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Rods, Cones, and More

• RODS/CONES?BIPOLAR cells ? GANGLION cells
• Axons of ganglion cells converge like strands of
  rope to form the optic nerve to the brain
• BLIND SPOT demonstration
• 1) card
• 2) Blindspot
• 3) Not the Blind Spot...but still pretty darn
  sweet
• 4) NEXT PAGE
• Hand out of the visual TRANSDUCTION
  process(slide)
• Magic Eye

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FOVEA
The fovea, shown here on the left, is the region
of the retina that provides for the most clear
vision. In the fovea, there are NO rods...only
cones. The cones are also packed closer together
here in the fovea than in the rest of the retina.
Also, blood vessels and nerve fibers go around
the fovea so light has a direct path to the
photoreceptors.
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You can eliminate the blind spot

• But only if you are an octopus!

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Gotta love (and have) the retina

• TRANSDUCTION YES, RODS/CONES?BIPOLAR cells ?
  GANGLION cells (axons converge in what is called
  the optic nerve and sends messages to the
  occipital lobe)
• About 130,000,000 receptors per retina

• Cones are for fine detail and color
• Cones only really work in the light
• Concentrated in the fovea
• 1 cone 1 bipolar cell Detailed vision

• Rods are more evenly distributed
• Many rods to one bipolar cell, so you can see in
  dim light, but only in black and white

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Just to be sure

• STIMULUS light energy
• Light speed (velocity) 186,000 miles / sec
• Transduction process of vision to brain
• Wavelength distance between electromagnetic
  wavelengths (peak to peak)
• Hue dimension of color determined by wavelength
  of light
• Amplitude (Intensity) the amount of energy in a
  light or sound wave

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Eye-ness

• Which eye is your dominant eye
• 1) Select an object that is a few feet away from
  you
• 2) Stare at the object and then point to the
  object using your index finger.
• 3) When your eyes are focused on the object and
  not on your finger, you will see two blurry
  fingers in your line of sight.
• 4) Now, close one eye and then close the other
  eye.
• Expected results with 1 of your eyes close, your
  index finger will point exactly at the object,
  however, when the other eye is closed, your
  finger will point at an area slightly shifted to
  the side of the object

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REVIEW and MORE fun stuff

• http//www.dls.ym.edu.tw/neuroscience/eyetr.html
  (this is an awesome eye web site (get it,
  haha!!)
• OVER VIEW!!
• Also, astigmatisms, near-sight, far-sight
• If time, ARTICLE on Putting a Light bulb in your
  mouth

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Interesting Problems

• What about Blindsight? (Replace with Worth 11)
• Blindsight (no time in class)
• Blindsight article (likely no time)
• 1) Clinically, what is blindsight?
• 2) What is the specific part of the visual cortex
  that is usually damaged in people with
  blindsightedness? (It has 2 names)
• 3) What have some argued is the relationship
  between visual consciousness and the particular
  part of the cortex the article discusses?
• 4) What other general explanations of
  consciousness does the author offer instead?
• How about just being blind?
• Diffs between newly blind and always blind
  people Visual Cortex Changes

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Another problem Prosopagnosia

• Complete sensation but incomplete perception
• Best example is the inability to recognize faces
• Example
• Stone Recognition

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Knowing all this Parallel Processing makes
sense

• Processing (of color, motion, form, and depth for
  example must be parallel, or simultaneous
• Just try to imagine doing it serially (or
  sequentially)!
• 130,000,000 receptors, one after the other
• You probably wouldnt live long enough to
  recognize a triangle
• The ability to process in this fashion could be
  blown out by a stroke
• So there are parts of the brain (neurons) for
  color, depth, movement, and form that each work
  independently yet simultaneously

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Color Vision

• Trichromat Ability to see all colors
• Dichromat Color blind in either
• Red-green (most common)
• Yellow-blue (dogs)
• Monochromat sees only light dark (gray,
  black, white, etc.) (rats)
• Figure 5-12 Color-Deficient Vision

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Color vision

• Young-Helmholtz Trichromatic theory
• Retina has three color receptors (cones) R, G, B
• R G Yellow R G B White
• Mixing paints is subtractive color mixing black
• Mixing lights is additive color mixing white
• Some problems though
• We see yellow when mixing red/green, so why can
  those who are blind to red and green can still
  see yellow?
• Afterimageyou stare at a coloryou see its
  opposite after turning away from it
• Handout 5-5 (guide ? 10)
• EXAMPLE Bird in a Cage Flag

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• Stare at this

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Opponent Process Theory

• Ewald Herings Opponent Process Theory
• Three types of cones
• Red-green
• Blue-yellow
• Black-white
• Every receptor fires in response to all
  wavelengths
• But, in each PAIR of receptors, 1 fires maximally
  to one wavelength
• EX Max firing for red receptor along with low
  rate of firing for green receptor
• Explains afterimages DUDE
• Also, there is no such thing as
  reddish-greenisheither one is on or the other
• So, in the retina and the thalamus, some neurons
  are turned on by red but turned off by green
• Black White Squares

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What Do They Do Well?

• Trichromatic Theory
• Explains the 3 classes of cones (RGB) and color
  coding at the retina
• Opponent Process Theory
• Explains color contrast (no such thing as a
  reddish-green) and color blindness (ppl tend to
  see red and green as the same color)

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Lets view some videos

• The Brain
• Visual Info Processing Elementary Concepts
• Perception Inverted vision
• The Mind
• Subliminal Perception

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HEARING some basic definitions

• Stimulus sound waves (760mph)
• Amplitude strength of a sound
• Frequency number of cycles in a sound wave
• Pitch high or low (longer wave is lower,
  shorter is higher)
• Hertz cycles of sounds waves per second
• Decibel 1/10 of a bel, a unit of measurement
  named after the inventor Bell

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Hearing

• Just like vision, we are converting one form of
  energy to another
• Sound is just changes in air pressure
• Sound pressure level
• 100 dB is 10 times louder than 90 dB

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The Ear

• Outer ear sort of sucks sound in towards the
  eardrum
• Middle ear transmits vibrations from the eardrum
  to hammer, anvil and stirrup
• Gets to the snail shaped cochlea in the inner ear
  (contains fluid)
• Fluid vibrates
• Movement detected by hair like projections on the
  basilar membrane (like wind bending a wheat
  field)
• Hair cells then trigger impulses in adjacent
  nerves, converge to form the auditory nerve and
  send neural messages to the temporal lobes
  auditory cortex!
• DONE!

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Pitch

• Frequency of sound
• Von Helmholtzs Place Theory
• Different frequencies make different parts of the
  basilar membrane vibrate
• High frequencies, start of cochlea
• Hmm, low frequencies are less localized
• Frequency theory
• Frequency of vibrations?
• If freq 100 waves/s, then 100 impulses/s to the
  brain
• Problem Neurons cannot fire over 1000times/s, so
  how do we hear over 1000 Hz?
• Volley Principle Neurons alternate firing like
  soldiers, so that their combined their frequency
  something above 1000/s
• In the end, it is probably both

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Sound Localization

• Sounds hit ears at different times, with
  different volumes (think about a car honking its
  hornyou turn to its direction)
• So left right distinction is really pretty easy
• Up down is VERY hard, if not impossible
• DEMONSTRATION VOLUNTEER (guide ? 13)
• Again, it is parallel processing
• Timing difference in one neural pathway
• Intensity differences in another
• Then, the information is merged, but we dont
  quite know how
• We usually do up down in concert with other
  senses

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Auditory Problems

• Middle Ear
• Conduction Deafness (conduction hearing loss)
• usually damage to tiny bones (cant vibrate) in
  the middle ear
• affects the mechanics of hearing
• hearing aid can help
• Amplifies high frequencies and compresses sound
  (amplifies soft, but not loud sounds)
• Inner Ear
• Nerve Deafness (Sensorineural hearing loss)
• Damage/Illness to cochlea (basilar membrane)
• Hearing aid or cochlear implant can help
• (Guide ? 14)

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Tinnitus

• Defined persistent sound in one or both
  earssound does not come from external source
• High pitched hiss, ring, buzz, or roar
• Continuous or pulsating (often coinciding with
  the heartbeat)
• Sound originates in the inside ear and is
  triggered by the auditory nerve
• Causes side effect of taking aspirin!, wax in
  outer ear, ear infection, impacted teeth,
  infected sinuses or tonsils, nerve disorders,
  arteriosclerosis, hypertension, loud noise, head
  injury, antibiotic drugs, Menieres disease
  (eventually causes hearing loss), otitis
  (inflammation of the ear)
• Explanation Science News

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Other senses

• Touch
• Pressure
• Warmth
• Cold
• Pain
• Pressure is easy to understand, 1 to 1
  relationship
• There are more receptors some places than other
  places
• Synesthesia (guide ? 14-15)
• Arrange the following colors black, brown, blue,
  green, red, yellow, and white in terms of high or
  lower pitch.
• Most say light colors have higher pitches.

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TouchIn the beginning

• Pain
• Descartes Pain is a physical phenomenon of
  injured nerves sending impulses to the brain
• 2 Point Thresholds (Guide ? 16)
• 2 toothpicks, 1 cm apart
• Touch cheek, then calf
• Touch fingertips, then forearm
• 2 toothpicks, 1 inch apart on crease of elbow
• Keep distance between toothpicks equal, draw
  them to the middle and index fingers

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Gate Control Theory

• Patrick Walls Gate Control Theory pain is
  gated by non-painful stimuli such as vibration
  top-down and bottom-up
• We have opioid receptors (all over the brain) to
  provide relief from pain actually, they inhibit
  firing of noxious stimuli sensing neurons, called
  nocioreceptors (slightly different than pain
  receptors)
• Dynorphins, enkephalins, and endorphins
• All the opiod receptors can be blocked by an
  antagonist Naloxone
• 3 major ways to inhibit perception of pain
• Periaquaductal grey matter (in midbrain)
• Nucleus raphe magnus (medulla)
• Pain inhibitory neurons in dorsal horn of the
  spinal cord
• Gate opens in response to small diameter fibers
  (pain)
• Closes gate in response to large diameter fibers
  (touch) (acupuncture is a gate closing
  activityalso rubbing a stubbed toe, a
  massageLamaze method of focusing your attention
  elsewhere) Darwin knew this Pain is increased
  by attending to it.
• Why Evolutionarily?
• Its important to detect and respond to pain
  because pain is a sign of impending danger
• In clinical application, the idea is to find a
  way to stimulate those large diameter nerves, so
  as to shut the gate to pain

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DiagramThen, Aspirin

• How does aspirin work?
• Actually doesnt work in the brain
• Blocks the production of prostaglandins
  throughout the body
• Prostaglandins (named by a Sweed who thought they
  were produced in the prostate) are in virtually
  every cell of the bodythey produce inflammation,
  pain, and fever when triggered by appropriate
  stimuli
• Aspirin blocks them from doing this

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More touch

• We prefer a tapering down of pain, rather than an
  immediate shut off
• Cold H2O for 60 seconds, or cold H2O for 60
  seconds followed by not so cold 30 secondspeople
  actually prefer the latter
• Video Phantom Limb Pain (The Mind 20) OR Worth
  4 Brain Reorganization Phantom Limb Sensations)
• Strangely enough there are different receptors
  for cold and warm

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• Type of Fibers
• A fibers myelinated, thin, fast transmitting,
  sharp, acute pain
• C fibers unmyelinated, aching, throbbing,
  burning pain
• CNS
• Neurons in spinal cord release glutamate (major
  excitatory NT)
• several sequential neurons all releasing
  glutatmate
• Signals sent to the thalamus
• Signals then sent to somatosensory cortex in the
  cerebrum (includes limbic system, cortex, basal
  ganglia, olfactory bulb)

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Briefly on Headaches

• Brain does not actually have any nocioceptive
  tissue cannot perceive pain
• So headaches CANNOT stimulation of pain fibers
  in the brain itself
• The membrane surrounding CNS, dura matter, has
  pain receptors
• Evolutionary, probably any injury that was severe
  enough to be able to cause pain in the brain
  would probably kill you first anyway

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Can plants feel pain?

• Since pain is defined as a signal of present or
  impending tissue damage affected by a harmful
  stimulus, the ability to experience pain or
  irritation is observable in most multicellular
  organisms. Even some plants have the ability to
  retract from a noxious stimulus. Whether this
  sensation of pain is equivalent to the human
  experience is debatable.

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Anesthesia

• Local anesthetic blocks Na channels Na cant
  get in no AP
• General anesthesia
• suppresses pain and awareness
• suppresses movement
• amnesia
• Examples nitrous oxide, halothane, propofol,
  barbiturates

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Taste

• Types of sensations Sweet, Sour, Salty, Bitter,
  Umami

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Taste

• Makes lots of evolutionary sense (poisonous stuff
  bad)
• Need the interaction with smell and vision

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• A bump 200 taste buds
• Doesnt take much to trigger a taste response
• Reproduce themselves every week or twodecreased
  total with age (decreased taste sensitivity
• Smoking and alcohol also declines the /
  sensitivity
• Interesting facts
• The sensations are inherited and are present from
  birth
• No tongue?? Sense through receptors on back /
  roof of mouth
• One side no longer sensitiveother side becomes
  supersensitive
• Sensory interaction one sense influences
  another (smell plus texture taste

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Smell (Olfaction)

• 5 million receptor cells at the top of each nasal
  cavitybut, we dont really know how they work!
• There is no R-G-B system
• 1000 genes or so code for 5 million receptors
• Peaks in early adulthood, gradually declines
  thereafter

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Smell (Olfaction)

• Dogs will track either twin (cant tell the
  difference)
• Smell is evolutionarily old! Before cerebral
  cortex evolved, ancestors sniffed for food and
  predators
• Brain gets info from the nose and the limbic
  system (emotion and meory) simultaneouslythis is
  why unique smells tend to trigger memories
• Top 10 smellable agents (guide ? 23)

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• "PHASE PORTRAITS" made from electroencephalograms
  (EEGs) generated by a computer model of the
  brain reflect the overall activity of the
  olfactory system during perception of a familiar
  scent (left). Resemblance of the portraits to
  irregularly shaped, but still structured, coils
  of wire reveals that brain activity in both
  conditions is chaotic complex but having some
  underlying order. The circular shape of the
  right-hand image, together with its segregation
  of color, indicates that olfactory EEGs are
  ordered-nearly periodic-during perception.

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Body Position and Movement

• A 6th sense kinesthesis awareness aroused by
  movements of and feedback from muscles, tendons,
  joints
• Proprioception stretch (muscles) receptors
• Activity 1 Close eyes, raise both hands above
  head. Keep fingers of left hand entirely still.
  With right hand, touch index fingertip to nose,
  then touch your left hand thumb with your right
  index fingertry each finger
• Activity 2 X on paperclose eyeshand up
  highmark a dot
• Activity 3 Write Proprioception close eyeson
  same line, write Proprioception
• Explanation proprioceptors in muscles, tendons,
  joints judge your body positions in all these
  activities

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Vestibular Sense

• A 7th sense! Vestibular sense monitors the
  heads (and thus the bodys) position and
  movement
• Semicircular canals (3-D pretzel) in the inner
  ear contains the sensory system for this
• Vestibular sacs connect the canals with the
  cochlea (fluid-filled)so, when the head rotates
  or tilts, this feels it
• Spinny bat You feel dizzy because you are
  spinning, causing the fluid to spin, you stop
  moving, but the fluid keeps spinningsomething is
  offyou feel dizzy
• Sends messages to the cerebellum
• Waterman of England contracted viral infection
  that destroyed nerves enabling him to sense light
  touch and body position
• He can only stand / move when the lights are on
• If lights go out, he crumples to the floor
• DEMONSTRATION
• Stand up
• Right heel in front of your left toes
• Close eyes!
• D2 guide 27

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I just cannot resist

• Beared Man (from http//mambo.ucsc.edu/demos.html
  )
• Backwards Speech?

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Some Fun

• Disappearing Act
• Changing Illusions...VOLUNTEERS!!!!
• Ponzo Illusion (playground)
• Horizontal - Vertical Lines Illusions
• Over the Mountain
• 3 Spinning Colors...The Phi Phenomenon
• Stepping Feet