Sensation and Perception

• Scientifically, what we see is not color but pulses of electromagnetic energy that our visual system perceives as color
• Light's wavelength determines the hue or the color we experience
• Intensity of light waves is determined by a wave's amplitude or height, influencing the brightness
• The eye allows light to enter through the Cornea, Aqueous Humor, Pupil, Iris, Lens, Visual accommodation, Vitreous Humor, and Retina
• The Retina has three layers: Ganglion Cells, Bipolar Cells, and Rods and Cones (photoreceptor cells)
• Rods are responsible for peripheral vision, see only in black and white and shades of gray
• Cones are responsible for color vision, located all over the retina but more concentrated at the fovea
• The Blind Spot is where all the axons of ganglion cells leave the retina to become the optic nerve, with no rods or cones
• Acuity or sharpness of vision can be affected by small distortions in the eye's shape
• Light entering the eyes can be separated into the left and right visual fields, with different areas of the retina processing information from different visual fields
• Adaptation occurs as the eye recovers its ability to see when going from a brightly lit state to a dark state, with rods adapting to low levels of light and cones adapting to increased light levels
• Visual information processing involves feature detection and parallel processing in the brain
• Color vision theories include the Trichromatic Theory and the Opponent Process Theory, which explains how we see colors and afterimages
• Color blindness can be caused by defective cones in the retina, resulting in different types of color deficiencies such as monochromatic and dichromatic vision
• Individuals with color blindness may have no cones or cones that are not working, leading to difficulties in distinguishing colors
• Vision
• Red-Green Color Deficiency:

  • Lack of functioning red or green cones
  • Individuals confuse reds and greens, see primarily in blues, yellows, and shades of gray
• Blue-Yellow Color Deficiency:

  • Lack of functioning blue cones
  • Individuals see primarily in reds, greens, and shades of gray
• Auditory Sensing
• Audition:

  • Sensation of hearing; the process of hearing
• Sound Waves:

  • Movement of air molecules brought about by a source of vibration
• Robert Boyle:

  • Demonstrated that sound requires a medium to move through, such as air, water, or a solid object
• Classic Experiment Robert Boyle's Amplitude:

  • Measured in decibels, determines the loudness of a sound wave
  • Amplitude of a light wave affects the brightness of a visual stimulus
• Frequency:

  • Measured in hertz, the number of sound waves or cycles per second, determines the pitch of the sound
• Timbre:

  • Refers to how high or low a sound is
  • The distinctive quality of a sound that distinguishes it from other sounds of the same pitch and loudness
• The Outer Ear
• Pinna:

  • Determines the source of sound and amplifies frequency of sound
• Auditory Canal:

  • Lined with skin and hairs which protect the eardrum
  • Modified sweat glands secrete cerumin to keep the canal moist
• Eardrum:

  • Receives the sound waves and transforms the sound energy into mechanical energy
• Middle Ear
• Hammer, Anvil, and Stirrup
• Inner Ear
• Two Labyrinths:

  • The semicircular canal, the organs of equilibrium
  • The cochlea, the organ for audition
• Theories of Hearing
• Theory proposed in 1863 by Hermann von Helmholtz and elaborated on by Georg von Békésy

  • Modern theory is a combination of the theory of place and the theory of frequency
• Frequency Theory:

  • Developed by Ernest Rutherford in 1886
• Theory developed by Ernest Wever (1949) and Charles Bray (1930)
• Adrian in 1931:

  • Argued that the microphonic effect is picked up in the cochlea rather than in the auditory nerve
• Licklider in 1951:

  • Described both the volley and the traveling wave theories as a single place theory
• Defects