Sensation and Perception

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Sensation and Perception

• By Emily Weig

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Basic Principles

• Sensation-sensory receptors and nervous system
  receive stimulus
• Perception-the process of organizing and
  interpreting sensory information, making it
  meaningful
• Bottom up processing-analysis that begins with
  the sensory receptors and works up to brains
  integration
• Top-Down Processing-information processing guided
  by higher level mental processes
• Selective attention- focusing on conscious
  awareness of a particular stimulus
• Inattentional blindness- failing to see visible
  objects when our attention is directed elsewhere
• Change blindness- failing to notice changes in
  the enviornment

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Thresholds

• Psychophyiscs- the study of relationships between
  the physical characteristics of a stimuli, such
  as their intensity and our psychological
  experience of them
• Absolute thresholds-minimum stimulation needed to
  detect
• Subliminal-below absolute threshold
• Signal detection theory-predicting how and when
  we detect the presence of a faint stimulus amid
  background stimulation, assumes there is not
  single absolute threshold
• Difference threshold-minimum difference needed to
  detect a difference 50 of the time
• Webers law the principle that to be perceived as
  different, tow stimuli must differ by a constant
  percentage
• Sensory adaptation- diminished sensitivity as a
  consequence of constant stimulation

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Vision

• Transduction-process of converting
  electromagnetic energy into neural impulses that
  we interpret as our sight
• Wavelength- distance from one wave to the next,
  determines hues
• Amplitude-height, determines the colors
  brightness
• Feature Detector cells in occipital lobe, allows
  you to perceive edges, angles and movements
• Parallel Processing, allows you to interpret
  color, movement, depth, and form all at once

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The Eye
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Color Vision

• Cones-have direct connection to the brain,
  allowing them to better evaluate color and
  detail, need light
• Rods-share connections with other rods, provide
  black and white vision, faint light
• Color is actually the light waves an object
  reflects
• Most color blind people lack red-green color
  sensitive cones
• Young Helmholtz trichromatic theory suggests that
  the eye has 3 color receptors, red, green, and
  blue
• Opponent Process theory suggests that there are 3
  processes one to see red or green, blue or
  yellow, and black and white

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Perception with Vision

• Gestalt Principles-organize visual elements into
  groups
• Similarity-pattern
• Continuation
• Closure
• Proximity
• Figure (object) and Ground (background)

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Depth Perception

• Eleanor Gibson-visual cliff-6 to 14 month old
  infants would not go off, even if coaxed, depth
  perception is inborn, grows with age
• Binocular cues-depth cues, that depend on two
  eyes
• Retinal Disparity-comparing images from the
  retinas in the two eyes the brain computes
  distance-the greater the difference the closer
  the object is
• Monocular cues, interposition and linear
  perspective available to either eye alone

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Vision Perception

• Phi phenomenon- illusion of movement created when
  2 or more adjacent lights blink on and off in
  quick succession
• Objects getting smaller (retreating) getting
  bigger (approaching)
• Size, shape, light, and color constancy

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Vision Perception

• Perceptual adaption, in vision, the ability to
  adjust to an artificially displaced or even
  inverted visual field
• Perceptual set-a mental predisposition to
  perceive one thing and not another
• Context matters
• How we feel
• What we know
• What we are doing

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Taste

• Types of Taste
• Salty
• Sweet
• Sour
• Bitter
• Umami-meat
• Gustatory Receptor cell-allows different taste
  sensations
• Gustatory Hair-extends from the cell and makes
  contact with food

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Tongue
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Touch

• Kinesthesis- system for sensing position and
  movement of individual body parts
• Vestibular sense- sense of body movement and
  position, including sense of balance
• Gate Control Theory-the theory that the spinal
  cord contains a neurological gate that blocks
  pain signals or allows them to pass on to the
  brain. The gate is opened by the activity of pain
  signals travelling up small nerve fibers and is
  closed by activity in larger fibers or by
  information coming from the brain

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Pain and skin

• Remember pain from its peak moment
• Not feeling pain (genetic disorder) feeling
  constant pain (chronic pain)
• Pain is how the body says something is wrong
• Placebo effect works well with pain, body will
  release natural pain killing opiates

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Rewards of Touch

• Harlows monkey
• Infant rats and premature babies gain weight
  faster if held
• Stress relieving
• Bonding
• Oxytocin- the cuddle hormone

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Smell

• Bypasses thalamus
• Not every smell has a specific receptor, smells
  are made through a blending of receptor signals
• Smell influences taste, evolutionary allowed
  people to eat good foods and not bad
• Smell related to memory, cookies in the oven
  grandmas house

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Process of smelling
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Hearing

• Place Theory- theory that links the pitch we hear
  with the place where the cochleas membrane is
  stimulate
• Frequency theory- theory that the rate of nerve
  impulses traveling up the auditory nerve matches
  the frequency of a tone thus enabling us to sense
  the pitch
• Conduction hearing loss-hearing loss caused by
  damage to the mechanical system that conducts
  sound waves to the cochlea
• Sensorineural hearing loss- hearing loss caused
  by damage to the cochleas receptor cells or to
  the auditory nerves
• Cochlear Implant- A device for converting sounds
  into electrical signals and stimulating the
  auditory nerve through electrodes threaded into
  the cochlea
• Time difference between the sound hitting one ear
  and then the other, helps us to locate sounds
• Frequency-number of waves per second, determines
  pitch

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Ear
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ESP

• Psychokinesis-levitating a table
• ESP-Perception occurring apart from sensory input
• Telepathy-mind to mind communication
• Clairvoyance- perceiving remote events-friends
  house on fire
• Precognition-perceiving future events- friends
  dying in accident
• There have been no studies actually proving the
  existence of these