Module 3 Lesson 1 - Sensations Flashcards
Sensation
A process in which sensory receptors (and the nervous system) receive and represent stimulus energies from an environment.
Transduction
Conversion of one form of energy into another.
In sensation, this transformation of stimulus energy (sights, sounds, smells) into neural impulses allows the brain to properly interpret them.
Absolute Threshold
The minimum stimulation required in order to detect a specific stimulus 50% of the time
Signal Detection Theory
A theory which predicts how and when a faint stimulus (signal) is detected amid background stimulation (noise). This assumes there is no single absolute threshold, and detection depends partly on a person’s experience, expectations, motivation, and alertness.
Subliminal Threshold
Below one’s absolute threshold for conscious awareness.
Difference Threshold
The minimal difference required between stimuli for detection 50% of the time. We experience this as a just noticeable difference (or jnd).
Sensory Adaptation
Diminished sensitivity due to constant stimulation.
Wavelength
The distance from the peak of one light or sound wave to the next. Electromagnetic wavelengths vary from short blips of cosmic rays to the long pulses of radio transmission.
Hue
The dimension of color is determined by the wavelength of light; we know these as color names (blue, green, etc…)
Olfactory Nerve
The first cranial nerve (CN1) and relays sensory information about smell to the brain. The shortest cranial nerve, it is the only cranial nerve with one trunk instead of two.
Pupil
The adjustable opening at the center of the eye; this is where light enters.
Iris
A ring of muscle tissue that forms the colored portion of the eye around the pupil, it is responsible for controlling the size of the pupil opening.
Lens
The transparent structure behind the pupil that changes shape to help focus images on the retina.
Retina
The light-sensitive inner surface of the eye, containing the receptor rods and cones, as well as layers of neurons that start with the processing of visual information.
Accommodation (lens)
A process in which the eye’s lens changes shape to focus near or far objects on the retina.
Rods
Retinal receptors that detect black, white, and gray; this is needed for peripheral and twilight vision, when cones do not respond.
Cones
Retinal receptor cells that are concentrated near the center of the retina, they function in daylight or well-lit conditions.
Optic Nerve
The nerve that carries neural impulses from the eye to the brain.
Blind Spot
The point at which the optic nerve leaves the eye to create a “blind spot.” This is because no receptor cells are located there.
Feature Detectors
Nerve cells in the brain respond to specific features of the stimulus, like shape, angle, or movement.
Depth Perception
The ability to see objects in 3 dimensions although the images that strike the retina are two-dimensional: allows us to judge distance.
Cornea
The see-thru area of the outer lining of the eyeball, through which light initially passes.
Convergence
The rotation of both eyeballs inward in the direction of light so the visual lies on correlating spots on the foveas. This lets the minutely variant visuals of an item viewed by each eyeball to join one another and shape one visual.
Farsighted
Medically known as hyperopia or hypermetropia, this is a condition that results from the eye’s physical inability to focus an image correctly on the retina at the back of the eye.
This is the result of the eyeball being too short, and/or the lens of the eye not being flexible enough, for proper focus to occur.
Foveal Vision
The fovea is the central focal point on the retina in the eye around where the cones cluster. In fact, the fovea has only cones around it for detecting fine detail better.
Ganglion Cells (Retinal Ganglion Cells)
Neurons in the retina that send visual stimulation signals to the brain.
Nearsighted
An eye condition where one cannot see objects clearly from afar.
Fovea
The central focal point in the retina around which the eye’s cones cluster.
Young-Helmholtz Theory
The theory that the retina contains three different color receptors - each of them most sensitive to either red, green, or blue - which, when stimulated in combination, can produce the perception of any color.
Opponent-Process Theory
The theory that opposing retinal processes (red - green, yellow - blue, white - black) enables color vision. For ex: Some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.
Audition
The sense or act of hearing
Middle Ear
The chamber between the eardrum and cochlea that contains three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window.
Inner Ear
The innermost part of the ear that contains the cochlea, semicircular canals, and vestibular sacs.
Cochlea
A coiled, bony, fluid-filled tube in the inner ear; sound waves travel through the cochlear fluid trigger nerve impulses.
Conduction Hearing Loss
Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.
Sensorineural Hearing Loss
Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerves; also called nerve deafness.
Cochlear Implant
A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.
Place Theory
In hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated.
Frequency Theory
In hearing, the theory that the rate of nerve impulses that travel up the auditory nerve matches the frequency of a tone, which enables us to sense its pitch.
Auditory Nerve
The portion of the eighth cranial nerve that deals exclusively with the sense of hearing. The nerve originates in the cochlea, where nerve fibers pass through several layers of nuclei in the brainstem and terminate in the auditory cortex. This is also known as the acoustic nerve-cochlear nerve.
Basilar Membrane
Structurally refers to a layer in the inner ear that separates the two fluid-filled tubes of the cochlea.
Gate-Control Theory
The theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain. The “gate” is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain.
Sensory Interaction
The principle that one sense may influence another, like when the smell of food influences the taste.