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• Sensation


  Conversion of energy from the environment into a pattern of response by the nervous system. Registration of information.
• Perception


  Interpretation of the information registered by the senses
• Receptors

  Specialized cells that convert environmental energies into signals for the nervous system
• Electromagnetic spectrum


  Continuum of all frequencies of radiated energy, from gamma rays to radio and TV transmissions
• Light is visible only because our receptors respond to wavelengths from 400 to 700 nanometers</b>
• Pupil

  • Adjustable opening that widens and narrows to control the amount of light entering the eye
• Iris

  • Colored structure on the surface of the eye surrounding the pupil
• Vitreous humor

  • Clear jellylike substance that light passes through to reach the retina
• Retina

  • Layer of visual receptors covering the back surface of the eyeball
• Cornea


  • Rigid transparent structure on the surface of the eyeball that always focuses light in the same way
• Lens


  • Flexible structure that varies its thickness to enable accommodation for objects at different distances
• Fovea


  • Central area of the human retina adapted for detailed vision with the greatest density of receptors
• Hawks, owls, and other predatory birds have a greater density of receptors on the top of the retina than on the bottom, allowing them to see the ground beneath them in detail
• Cones

  Visual receptors adapted for perceiving color and detail in bright light
• Rods


  Visual receptors adapted for vision in dim light
• About 5% of visual receptors in the human retina are cones, but they send more axons to the brain than the rod-rich areas and dominate the visual cortex
• Rods are more effective than cones for detecting dim light because they respond more to faint stimulation and pool their resources more
• Young-Helmholtz or Trichromatic Theory


  Color vision depends on the relative responses of three types of cones to short, medium, and long wavelengths
• Opponent Process Theory


  We perceive color in terms of paired opposites - red versus green, yellow versus blue, and white versus black
• Negative afterimages


  Experiences of one color after the removal of another
• Pinna


  • Fleshy structure that funnels sounds to the inner ear
• Frequency


  Number of cycles (vibrations) per second, designated in hertz (Hz)
• Pitch


  Perception closely related to frequency
• Loudness


  Perception of the intensity of sound waves
• Timbre


  Tone complexity, referring to the ratio of harmonics produced by an instrument or voice
• Prosody


  Conveying emotional information by tone of voice
• Cochlea


  • Snail-shaped organ containing the receptors for hearing
• Hammer, anvil, and stirrup


  • Three tiny bones that transmit vibrations from the eardrum to the cochlea
• Conduction deafness


  Hearing loss resulting from the bones connected to the eardrum failing to transmit sound waves properly to the cochlea
• Nerve deafness


  Hearing loss resulting from damage to the cochlea, hair cells, or auditory nerve
• Vestibular sense


  Sense that detects the tilt and acceleration of the head, and the orientation of the head with respect to gravity
• The vestibular system consists of three semicircular canals and two otolith organs that detect head movements and orientation
• Cutaneous senses


  Sensations of pressure, warmth, cold, pain, itch, vibration, movement, and skin stretch
• Anterior cingulate cortex


  Brain area responsive to the emotional aspect of pain
• Gate theory of pain


  The idea that pain messages must pass through a gate in the spinal cord that can block the messages
• Phantom limb


  Continuing sensations, including pain, in a limb long after it has been amputated
• Taste receptors


  Located in the taste buds on the surface of the tongue
• Traditional Western cultures recognize four primary tastes: sweet, sour, salty, and bitter
• Olfactory receptors


  Located on the mucous membrane in the rear air passages of the nose
• We can distinguish among more than a trillion odors and their mixtures through combinations of responses from our hundreds of types of olfactory receptors