Unit 3 - Sensation

Sensation

the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

Transduction

conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret

Wavelength

the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission

Intensity

the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude

Photoreceptor

a receptor that responds to light

Hue

the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth

Visible spectrum

The tiny part of the electromagnetic spectrum to which our eyes are sensitive.

Cornea

The clear tissue that covers the front of the eye

Iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

Pupil

the adjustable opening in the center of the eye through which light enters

Lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

Aqueous humor

the clear fluid filling the space in the front of the eyeball between the lens and the cornea.

Vitreous humor

jellylike substance found behind the lens in the posterior cavity of the eye that maintains its shape

Retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

Visual accommodation

the change in the thickness of the lens as the eye focuses on objects that are far away or close

Rods

retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision

Cones

retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. They detect fine detail and give rise to color sensations

Fovea

the central focal point in the retina, around which the eye's cones cluster

Optic nerve

the nerve that carries neural impulses from the eye to the brain

Optic chiasm

the point in the brain where the visual field information from each eye "crosses over" to the appropriate side of the brain for processing

Strabismus

crossed eyes

Peripheral vision

ability to see objects as they come into the outer edges of the visual field

Tunnel vision

a narrow field of vision (140 degrees or less); loss of peripheral vision

Blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

Saccade

A type of eye movement, made both voluntarily and involuntarily, in which the eyes rapidly change fixation from one object or location to another.

Dark adaptation

the adjustment of the eye to low light intensities, involving reflex dilation of the pupil and activation of the rod cells in preference to the cone cells.

Rhodopsin

the pigment in rod cells that causes light sensitivity

Feature detectors

nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement

Parallel processing

the processing of many aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision. Contrasts with the step-by-step (serial) processing of most computers and of conscious problem solving.

Trichromatic

three cones for receiving color (blue, red, green)

Opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

Afterimage

A visual image that persists after a stimulus is removed.

Visual acuity

the ability to see fine detail

Myopia

nearsightedness

Presbyopia

farsightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.

Snellen test

a distance visual acuity test which determines the smallest letters that can be read on a chart from a distance of 20 feet away

Astigmatism

a condition in which the eye does not focus properly because of uneven curvatures of the cornea

Cataracts

clouding of the lens

Conjunctivitis

inflammation of the conjunctiva (pink eye)

Glaucoma

increased intraocular pressure results in damage to the retina and optic nerve with loss of vision

Color blindness

A sex-linked trait in which an individual cannot perceive certain colors.

Audition

the sense or act of hearing

Sound waves

Successive pressure variations in the air that vary in amplitude and wavelength.

Amplitude

Height of a wave

Decibels (dB)

A unit of measurement of loudness

Pitch

a tone's experienced highness or lowness; depends on frequency

Frequency

the number of complete wavelengths that pass a point in a given time

Hertz

the unit of frequency, equal to one cycle per second

Echolocation

the process of using reflected sound waves to find objects; used by animals such as bats

Ultrasound

Sound waves with frequencies above the normal human range of hearing

Pinna

external ear

Auditory canal

channel that leads from the pinna to the eardrum

Tympanic membrane

a membrane forming part of the organ of hearing, which vibrates in response to sound waves. In humans and other higher vertebrates it forms the eardrum, between the outer and middle ear.

Middle ear

the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window

Auditory ossicles

three small bones linked together that connect the eardrum to the inner ear

Malleus

hammer; a small bone in the middle ear that transmits vibrations of the eardrum to the incus.

Incus

a small anvil-shaped bone in the middle ear, transmitting vibrations between the malleus and stapes.

Stapes

stirrup; last of the three auditory ossicles of the middle ear

Inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

Cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

Hair cells

specialized auditory receptor neurons embedded in the basilar membrane

Auditory nerve

the nerve that carries impulses from the inner ear to the brain, resulting in the perception of sound

Place theory

the theory that links the pitch we hear with the place where the cochlea's membrane is stimulated

Frequency theory

theory of pitch that states that pitch is related to the speed of vibrations in the basilar membrane

Conductive hearing loss

hearing impairment caused by interference with sound or vibratory energy in the external canal, middle ear, or ossicles

Nerve deafness

Hearing loss created by damage to the hair cells or the auditory nerve fibers in the inner ear.

Cochlear implant

a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea

Sensorineural hearing loss

hearing impairment caused by lesions or dysfunction of the cochlea or auditory nerve

Olfaction

sense of smell

Gustation

sense of taste

Somesthetic senses

the body senses consisting of the skin senses, the kinesthetic sense, and the vestibular senses

Vestibular sense

the sense of body movement and position, including the sense of balance

Kinesthetic sense

sense of the location of body parts in relation to the ground and each other

Chemical senses

smell and taste

Pheromones

biochemical odorants emitted by other members of its species that can affect an animal's behavior or physiology

Papillae

taste buds

Otolith organs

utricle and saccule; the mechanical structures in the vestibular system that sense both linear acceleration and gravity

Proprioception

The ability to tell where one's body is in space.

Sensory conflict theory

explains motion sickness as the result of a mismatch among information from vision, the vestibular system, and kinesthesis

Sensory adaptation

diminished sensitivity as a consequence of constant stimulation

Sensory habituation

our perception of sensations is partially due to how focused we are on them

Nociceptors

sensory receptors that enable the perception of pain in response to potentially harmful stimuli

Visceral pain

a poorly localized, dull, or diffuse pain that arises from the abdominal organs, or viscera

Referred pain

pain that is felt in a location other than where the pain originates

Somatic pain

Pain that originates from skeletal muscles, ligaments, or joints.

Gate-control theory of pain

a theory of pain perception based on the idea that signals arriving from pain receptors in the body can be stopped, or gated, by interneurons in the spinal cord via feedback from two directions

McGurk effect

an error in perception that occurs when we misperceive sounds because the audio and visual parts of the speech are mismatched.

Multimodal perception

the approach that considers how information that is collected by various individual sensory systems is integrated and coordinated