Chapter 3
Human Senses
↕almost all sensory input routed through the thalamus on its way to specific regions of the brain
↕vision- input sent from retina down the optic nerve to the thalamus and then onto the primary visual area
↕hearing- sound waves cause vibrations in the ear which reach the cochlea and are sent to the primary auditory area
↕touch- touch receptors send information up the spinal cord to the somatosensory area
↕ taste- soluble chemicals activate taste buds which sends input through cranial nerves to limbic regions of the brain
↕smell- olfactory receptors in nasal passage sensitive to chemicals in air, goes to olfactory bulb not thalamus
↕vestibular sense and kinesthesis- information about balance and position in space sent to brainstem and cerebellum
↕skin senses- besides receptors for senses of touch, the skin gather information on pain and temperature
↕sensory systems are sensitive to changes in stimulation level
↕sensory receptors require a minimum amount of energy for activation
↕light enters the eye through the cornea passes through the pupil and is focused by the lens onto the retina
↕light must pass between the ganglion cells and the bipolar cells to reach the rods and cones. The sensory message then travel back out from the receptor cells, via the bipolar cells, to the ganglion cells. The axons of the ganglion cells gather together to form the optic nerve, which carries the messages from both eyes to the brain
↕wavelengths- the different energies represented in the electromagnetic spectrum
↕absolute threshold- the least amount of energy that can be detected as a stimulation 50% of the time
↕adaptation- an adjustment of the sense to the level of stimulation they are receiving
↕additive color mixing- the process of mixing lights of different wavelengths to create new hues
↕afterimage- sense experience that occurs after a visual stimulus has been removed
↕amplitude- the magnitude of a wave; in sound, the primary determinant of loudness
↕auditory nerve- the bundle of axons that carries signals from each ear to the brain
↕basilar membrane- vibrating membrane in the cochlea of the inner ear; it contains sense receptors for sound
↕binocular cues- visual cues requiring the use of both eyes
↕bipolar cells- neurons that have only one axon and one dendrite ; in the eye, these neurons connect the receptors on the retina to the ganglion cells
↕blind spot- the place on the retina where the axons of all ganglion cells leave the eye
↕brightness- the nearness of a color to white as opposed to black
↕cochlea- part of the inner ear containing fluid that vibrates, which in turn causes the basilar membrane to vibrate
↕cones- receptor cells in the retina responsible for color vision
↕convergence- a visual depth cue that comes from muscles controlling eye movement as the eyes turn inward to view a nearby stimulus
↕cornea- the transparent protective coating over the front part of the eye
↕dark adaptation- increased sensitivity of rods and cones in darkness
↕decibel- unit of measurement for the loudness of sound
↕different threshold or just-noticeable difference (jnd)- the smallest change in stimulation that can be detected 50% of the time
↕feature detectors- specialized brain cells that only respond to particular elements in the visual field such as movement or line of specific orientation
↕fovea- the area of the retina that is the center if the visual field
↕frequency- the number of cycles per second in a wave; in sound, the primary determination of pitch
↕frequency theory- pitch is determinant by the frequency with which hair cells in the cochlea fire
↕ganglion cells- neurons that connect the bipolar cells in the eyes to the brain
↕hertz (hz)- cycles per second; unit of measurement for the frequency of sound waves
↕hues- the aspects of color that correspond to names such as red, green and blue
↕interposition- monocular distance cue in which one object, by partly blocking a second