Sensation and Perception Rapid Review for AP Psychology (page 2)
A more in-depth study guide for this review can be found at:
Sensation—the process by which you detect physical energy from your environment and encode it as neural signals.
Psychophysics—the study of the relationship between physical energy and psychological experiences.
Stimulus—a change in the environment that can be detected by sensory receptors.
Absolute threshold—the weakest level of a stimulus that can be correctly detected at least half the time.
Signal detection theory—maintains that minimum threshold varies with fatigue, attention, expectations, motivation, emotional distress, and from one person to another.
Difference threshold—minimum difference between any two stimuli that a person can detect 50% of the time.
Just noticeable difference (jnd)—experience of the difference threshold.
Weber's law—difference thresholds increase in proportion to the size of the stimulus.
Subliminal stimulation—receiving messages below one's absolute threshold for conscious awareness.
Transduction—transformation of stimulus energy to the electrochemical energy of neural impulses.
Perception—the process of selecting, organizing, and interpreting sensations, enabling you to recognize meaningful objects and events.
Vision and the human eye:
Rays of light from an object pass from the object through your cornea, aqueous humor, pupil, lens, and vitreous humor before forming an image on your retina.
Cornea—transparent, curved layer in the front of the eye that bends incoming light rays.
Iris—colored muscle surrounding the pupil that regulates the size of the pupil opening.
Pupil—small adjustable opening in the iris that is smaller in bright light and larger in darkness.
Lens—structure behind the pupil that changes shape, becoming more spherical or flatter to focus incoming rays into an image on the light-sensitive retina.
Accommodation—process of changing the curvature of the lens to focus light rays on the retina.
Retina—light-sensitive surface in the back of the eye containing rods and cones that transduce light energy. Also has layers of bipolar cells and ganglion cells that transmit visual information to the brain.
Fovea—small area of the retina in the most direct line of sight where cones are most concentrated for highest visual acuity in bright light.
Photoreceptors—modified neurons (rods and cones) that convert light energy to electrochemical neural impulses.
Rods—photoreceptors that detect black, white, and gray and that detect movement. Rods are necessary for peripheral and dim-light vision when cones do not respond. Distributed throughout the retina, except none are in the fovea.
Cones—photoreceptors that detect color and fine detail in daylight or in bright-light conditions. Most concentrated at the fovea of the retina, none are in the periphery.
Optic nerve—nerve formed by ganglion cell axons; carries the neural impulses from the eye to the thalamus of the brain.
Acuity—ability to detect fine details, sharpness of vision. Can be affected by small distortions in the shape of the eye.
Normal vision—rays of light form a clear image on the retina of the eye.
Nearsighted—too much curvature of the cornea and/or lens focuses image in front of the retina so nearby objects are seen more clearly than distant objects.
Farsighted—too little curvature of the cornea and/or lens focuses the image behind the retina, so distant objects are seen more clearly than nearby objects.
Dark adaptation—increased visual sensitivity that gradually develops when it gets dark.
Bipolar cells—second layer of neurons in the retina that transmit impulses from rods and cones to ganglion cells.
Ganglion cells—third layer of neurons in the retina, whose axons converge to form the optic nerve.
Blind spot—region of the retina where the optic nerve leaves the eye so there are no receptor cells; creates an area with no vision.
Feature detectors—individual neurons in the primary visual cortex/occipital lobes that respond to specific features of a visual stimulus.
Parallel processing—simultaneously analyzing different elements of sensory information, such as color, brightness, shape, etc.
Trichromatic theory—proposed mechanism for color vision with cones that are differentially sensitive to different wavelengths of light; each color you see results from a specific ratio of activation among the three types of receptors.
Opponent-process theory—proposed mechanism for color vision with opposing retinal processes for red–green, yellow–blue, white–black. Some retinal cells are stimulated by one of a pair and inhibited by the other.
Sensory adaptation—temporary decrease in sensitivity to a stimulus that occurs when stimulation is unchanging.
Attention—the set of processes from which you choose among the various stimuli bombarding your senses at any instant, allowing some to be further processed by your senses and brain.
Hearing and the human ear:
Audition—the sense of hearing. The loudness of a sound is determined by the amplitude or height of the sound wave.
Frequency—the number of complete wavelengths that pass a point in a given amount of time. The wavelength is inversely proportional to the frequency. Frequency or wavelength determines the hue of a light wave and the pitch of a sound.
Pitch—the highness or lowness of a sound. The shorter the wavelength, the higher the frequency, the higher the pitch. The longer the wavelength, the lower the frequency, the lower the pitch.
Timbre—the quality of a sound determined by the purity of a waveform. What makes a note of the same pitch and loudness sound different on different musical instruments.
Sound localization—the process by which you determine the location of a sound. The outer ear includes the pinna, the auditory canal, and the eardrum. The middle ear includes three tiny bones: the hammer, anvil, and stirrup. The inner ear includes the cochlea, semicircular canals, and vestibular sacs.
Cochlea—snail-shaped fluid-filled tube in the inner ear with hair cells on the basilar membrane that transduce mechanical energy of vibrating molecules to the electrochemical energy of neural impulses. Hair cell movement triggers impulses in adjacent nerve fibers.
Auditory nerve—axons of neurons in the cochlea converge transmitting sound messages through the medulla, pons, and thalamus to the auditory cortex of the temporal lobes.
Place theory—the position on the basilar membrane at which waves reach their peak depends on the frequency of a tone. Accounts well for high-pitched sounds.
Frequency theory—the rate of the neural impulses traveling up the auditory nerve matches the frequency of a tone, enabling you to sense its pitch. Frequency theory explains well how you hear low-pitched sounds.
Conduction deafness—loss of hearing that results when the eardrum is punctured or any of the ossicles lose their ability to vibrate. A hearing aid may restore hearing.
Nerve (sensorineural) deafness—loss of hearing that results from damage to the cochlea, hair cells, or auditory neurons. Cochlear implants may restore some hearing.
Somatosensation—the skin sensations: touch/pressure, warmth, cold, and pain.
Gate-control theory—pain is experienced only if the pain messages can pass through a gate in the spinal cord on their route to the brain. The gate is opened by small nerve fibers that carry pain signals and closed by neural activity of larger nerve fibers, which conduct most other sensory signals, or by information coming from the brain.
Kinesthesis—body sense that provides information about the position and movement of individual parts of your body with receptors in muscles, tendons, and joints.
Vestibular sense—body sense of equilibrium with hairlike receptors in semicircular canals and vestibular sac in the inner ear.
Gustation—the chemical sense of taste with receptor cells in taste buds in fungiform papillae on the tongue, on the roof of the mouth, in the throat. Molecules must dissolve to be sensed. Five basic taste sensations are sweet, sour, salty, bitter, and newly added to the list, umami or glutamate. Flavor is the interaction of sensations of taste and odor with contributions by temperature, etc.
Olfaction—the chemical sense of smell with receptors in a mucous membrane (olfactory epithelium) on the roof of the nasal cavity. Molecules must reach the membrane and dissolve to be sensed. Olfactory receptors synapse immediately with neurons of the olfactory bulbs in the brain with no pathways to the thalamus.
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