Transduction
The process of a sense organ changing physical energy into electrical signals that become neural impulses.
Adaptation
As the amount of time exposed to a continuous level of stimulation increases, the response from the sense organs decreases.
Sensations
Meaningless information bits, result from the brain processing electrical signals that come from the sense organs.
Perceptions
Meaningful sensory experiences resulting from the brain combining different sensations.
Visible Spectrum
One segment of electromagnetic energy that we can see.
Cornea
Rounded, transparent covering of front of eye. Focuses light waves into narrower beams as they enter the eye.
Pupil
Round opening at front of eye, allows light waves to pass into the eye's interior.
Iris
Circular muscle surrounding the pupil, controls amount of light entering the eye by relaxing and dilating.
Lens
Transparent, oval structure inside the eye, focuses light waves into an even narrower beam.
Retina
Thin film at back of eye, contains photoreceptors that begin the process of transduction.
Nearsightedness
The eyeball is too long, objects are focused at a point in front of the retina.
Farsightedness
The eyeball is too short, objects are focused at a point slightly behind the retina.
Cones
Photoreceptors that activate in bright light and allow us to see color and fine details.
Rods
Photoreceptors that are activated by small amounts of light and allow us to see in dim light, but to only see black, white, and shades of gray.
Trichromatic Theory
Says there are three different kinds of cones in the retina, corresponding to a different color: blue, green, or red. Other colors can be mixed from those primary colors.
Afterimage
A visual sensation that continues after the original stimulus is removed.
Opponent-process Theory
Says that ganglion cells in the retina respond to two colors: red-green and blue-yellow. When cells are excited they respond to one color pair; when inhibited they respond to the complementary pair.
Color Blindness
The inability to distinguish two or more shades in the color spectrum.
Monochromats
Total color blindness: black and white images. Results from individuals having only rods or one kind of functioning cone.
Dichromats
Individuals have trouble distinguishing red from green, have only two kinds of cones. Caused by an inherited genetic defect.
Sound waves
The stimuli for hearing, resemble ripples of different sizes, have different amplitudes and frequencies.
Loudness
Our subjective experience of a sound's intensity, calculated by the brain using the wave's amplitude.
Pitch
Our subjective experience of a sound being high or low, calculated by the brain using the wave's frequency.
Decibel
A unit used to measure loudness.
Outer Ear
The external ear, auditory canal, and tympanic membrane.
External Ear
The part of the ear that protrudes from the side of the head, picks up sound waves to send them further into the ear.
Auditory Canal
A long tube that funnels sound waves to the tympanic membrane.
Tympanic Membrane
A taut, thin structure (eardrum), sound waves strike it and cause it to vibrate.
Middle Ear
A bony cavity containing the ossicles, sealed at both ends by membranes.
Ossicles
Three tiny bones: the hammer, anvil, and stirrup. Transfer vibrations from the tympanic membrane to the cochlea.
Cochlea
Located in the inner ear, transforms vibrations into nerve impulses so they can be sent to the brain (transduction).
Hair Cells
Miniature hair-shaped cells that stick up from the cochlea's bottom membrane. Bend from vibration of the fluid in the cochlea, which generates miniature electrical forces that trigger transduction.
Basilar Membrane
The cochlea's bottom membrane.
Auditory Nerve
A band of fibers that carry nerve impulses to the auditory cortex of the brain for processing.
Primary Auditory Cortex
Transforms nerve impulses into basic auditory sensations.
Auditory Association Area
Receives meaningless auditory sensations in the form of neural impulses and combines them into perceptions.
Direction of a Sound
Brain determines this by calculating the slight difference in time it takes sound waves to reach the two ears.
Frequency Theory
Says the rate at which nerve impulses reach the brain determines how low the pitch of a sound is (applies only to low sounds)
Place Theory
Says the brain determines medium- to higher-pitched sounds on the basis of the place on the basilar membrane where maximum vibration occurs.
Vestibular System
Includes three semicircular canals which are filled with fluid that moves in response to the movements of your head. Helps sense the position of the head, keep the head upright, and maintain balance.
Motion Sickness
Feelings of discomfort, nausea, and dizziness in a moving vehicle. Develops when there is a sensory mismatch between information from vestibular system and from the eyes.
Meniere's Disease
Malfunction of the semicircular canals. Symptoms include sudden attacks of dizziness, nausea, vomiting, spinning, and head-splitting buzzing sounds.
Vertigo
Symptoms: dizziness and nausea. Caused by malfunction of the semicircular canals.
Taste
A chemical sense. Four basic tastes are sweet, salty, sour, and bitter.
Taste Buds
Receptors for taste.
Flavor
An experience resulting from the combination of taste and smell.
Olfaction
The sense of smell, a chemical sense.
Olfactory Cells
Receptors for smell located in uppermost part of nasal passages.
Touch
A sense that includes pressure, temperature, and pain.
Somatosensory Cortex
Transforms nerve impulses into sensations of touch. Different parts of the body are represented on different areas of the cortex.
Disgust
A feeling and facial expression triggered by the presence of a variety of contaminated or offensive things.
Placebo
Some intervention that resembles medical therapy, but that has no medical effects.
Placebo Effect
A change in the patient's illness that is due to the patient's beliefs/expectations rather than the medical treatment.
Double-blind Procedure
Neither the researchers nor the subjects know who is receiving what treatment.
Pain
An unpleasant sensory and emotional experience that may result from tissue damage, etc.
Gate Control Theory of Pain
Says that non-painful nerve impulses compete with pain impulses in trying to reach the brain, limiting the number of impulses that can reach the brain. So, shifting attention from pain should reduce it.
Endorphins
Chemicals produced by the brain that are secreted in response to injury, etc. Has pain-reducing properties.
Acupuncture
A procedure in which thin needles are inserted into various points on the body's surface to reduce certain kinds of pain.
Conduction Deafness
Caused by interference with the transmission of vibrations from the tympanic membrane to the fluid of the cochlea, resulting in degrees of hearing loss.
Neural Deafness
Damage to the hair cells or auditory nerve, which prevents the nerve impulses to reach the brain.
Cochlear Implant
An electronic device surgically implanted into the cochlea reduce the effects of neural deafness.