Vision & Audition
Page 20
October 15, 2010

Stimuli
 Distal:
as in the environment
 Proximal: as on the retina
 The Biology
 Cornea:
protection
 Lens
 Curvature accommodates for dist.
 Retina
 Cones: center – code for color
 Rods: periphery – dark, movement
 Optic Nerve
 Transmits images to both hemis.
 Occipital Lobe
 Perceives images based on color,
movement, depth, & form
 Trichromatic Theory
• aka Young-Helmholtz Theory
• Cones interpret stimuli in blue, red & green frequencies
 Opponent
Process Theory
• Thalamus codes for
 Black or White
 Red or Green
 Blue or Yellow
• Afterimage
• Colorblindness

Stimuli
• 0 decibels (20 Hz)
• 150 decibels (20,000 Hz)

The Biology
• Outer Ear
 Pinna: channel sound waves
• Middle Ear
 Tympanic Membrane
 Sound waves vibrate the ear drum
 Malleus (Hammer), Incus (Anvil),
Stapes (Stirrup)
 Amplify vibrations
• Inner Ear
 Cochlea: home to neurons
 Auditory Nerve
 Transfer message brain
• Temporal Lobe
 Perceives auditory stimuli
 Georg
von Bekesy (1961 – Nobel Prize)
• The cochlea interprets sound wave frequencies
• Higher frequencies stimulate more neurons
 Place Theory
• Different “places” along the cochlea activated
• Problem: < 4,000 Hz
 Frequency Theory
• Pitch determined by the frequency of sound waves
• Problem: differences of >1,000 Hz
• Volley Principal: alternate firing of neurons
 Conductive Deafness
• Injury to the outer or middle ear
• Treatment: medication, surgery, or hearing aid
 Sensorineural (Nerve) Deafness
• Injury to the inner ear
• Treatment: hearing aides or cochlear implant