Chapter 4

• Vision - Occurs when light enters the eye and strikes the retina. The brain translates stimuli


  Takes place in the brain
• Stimuli - Energies from the outside world around us that affect us in some way


  Sight, Sound, Smell, Texture, Taste
• Sensory Receptors - Specialized cells that convert environmental energies into signals for the nervous system 


  Types of Sensory Receptors - Touch, Pain, Heat, Cold, Pressure, Smell, Taste

  Types of Sensory Organs - Eyes, Ears, Nose, Skin, Tongue
• The receptors that allow us to hear don't also allow up to interpret what we're hearing or where the sound is coming from
• Pupil - an adjustable opening that widens and narrows to control the amount of light entering the eye
• Iris - The colored structure on the surface of the eye surrounding the pupil
• Retina - A layer of visual receptors covering the back surface of the eyeball
• Cornea - Rigid transparent layer on the surface of the eyeball. Focuses light the same way.
• Lens - A flexible structure that varies it thickness. Bends and focuses light to create a clear image


  The lens can cause vision problems and can be replaced to treat some conditions (cataracts)
• Fovea - The central area of the retina, adapted for detailed vision. 


  Contains more cones than rods
• Rods - Adapted for vision in dim light


  Cones - Adapted for perceiving color and detailing bright light
• The Visual Pathway - Light enters the eye through the pupil and strikes the retina. The light is changed into neuron impulses which are understood by the brain

  
• Structures of the Eye

  A) Iris

  B) Pupil

  C) Cornea

  D) Lens

  E) Retina

  F) Optic Nerve

  
• Metaphorical Use of Sensation

  • "I see what you mean"
  • "I feel your pain"
  • "She has good taste"
  • "Their actions are disgusting"
  • "Sounds like a good thing"

  The overlapping of senses
• Sensory situations and expressions cause us to feel and misinterpret things
• The pinna (ear) funnels sound to the inner pinna, where the receptors lie. The ear converts sound waves into mechanical displacements along the row of receptor cells
• Sound Waves - vibrations of the ear, water, or any other medium. Vary in frequency and amplitude. 


  The frequency of a sound wave is the number of cycles (vibrations) per second - Hertz (Hz)
• Pitch - perception closely related to frequency

  • High frequency sound wave = High Pitched
  • Low-frequency sound wave = Low Pitched
• Timbre - tone complexity, the sound difference is due to timbre
• Cochlea - the ear converts weak sound waves into more intense waves of pressure in the fluid-filled canals of the snail-shaped organ (cochlea) which is responsible for hearing.
• Hearing Loss:

  • Conduction Deafness - results when the bones (Incus, Malleus, Stapes) connected to the eardrum fail to transmit sound waves properly to the cochlea
  • Nerve Deafness - results when there is damage to the cochlea, hair cells, or auditory nerve
• Pitch Perception:

  • Children can hear pitches at higher frequencies than adults
  • Dogs can hear pitches at higher frequencies than humans
• Prosody - emotion in pitch, the ability to change your voice in a way that transmit and interpret emotion in speech

  • intonation, stress pattern, loudness variation, pausing, rhythm, duration, accents
• The Cutaneous Senses

  • Skin Senses
  • Somatosensory System (body-sensory system)
• Sound starts off as a mechanical process and turns into a chemical process when it interacts with receptors in the cochlea
• Pain

  • Mixture of body sensation and emotional reaction which depend on different brain areas.
  • Physical pain can be intense at the moment, but emotional pain is more enduring.
• Phantom Limbs- continuing sensations including pain in a limb long after it has been amputated


  Neuroplasticity - when a portion of the brain is unused, surrounding areas tries to move into the region, so when that area of the brain is interacted with it triggers impulses in its adjacent part and the phantom part that is has intruded to.
• If your hand has been amputated you are most likely to feel phantom sensation after touching your face


  Reason: because of how the cortex is wired
• Treatments for Phantom Pain:

  • Mirror Therapy
  • Physical Therapy/Massage Therapy
  • Artificial Limbs
  • Medications (ex. Antidepressants)
  • Acupuncture
• The Chemical Senses

  • Taste-Receptors are in the taste buds
  • Smell/Olfaction-Receptors are located on the mucous membrane in the rear air passage of the nose
• Synesthesia - a condition in which a stimulus of one type, such as sound, also elicits another experience, such as a color
• Subliminal Perception - the phenomenon that a stimulus can influence behavior even when it is presented so faintly or briefly that the observer has no conscious perception of it

  • Commercials
  • Musical Provocation
  • Faint audio messages used to improve memory

  Stimulus - something outside of us, we experience with our senses
• Gestalt Psychology - deals with perception

  • Bottom-Up Process - Tiny elements combine to produce larger items
  • Top-Down Process - You apply your experiences and expectations to interpret each item in context


  Bottom-Up - you come into class for the first time and you see people with their devices off and their pencils out, you assume there is a test

  Top-Down - you've checked the calendar so you come to class with only a pencil because you know there is a test
• Perception of Movement

  • Induced Movement - incorrectly perceiving an object as moving (ex. eyes of a painting following you)
  • Stroboscopic Movement - an illusion of movement created by a rapid succession of stationary images (ex. flipbook)
• Perception of Depth:

  • Binocular Clues - retinal disparity or convergence, depends on both eyes
  • Monocular Clues - judging depth and distance with just one eye or when both eyes see the same image (image appears differently)