| A | B |
|---|
| absolute sensory threshold | the intensity at which a given individual can detect a sensory stimulus 50% of the time: a low threshold indicates the ability to detect faint stimuli |
| accommodation of the lens | an adjustment of the thickness of the lens to focus on objects at different distances |
| binoculas cues | visual cues that depend on the action of both eyes |
| binocular rivalry | the alteration between seeing the pattern in the left retina and the pattern in the right retina |
| blind spot | the area where the optic nerve exits the retina |
| brightness contrast | an increase or decrease in an object's apparent brightness because of the effects of objects around it |
| capsaicin | a chemical that stimulates the release of substance |
| cataract | a disorder in which the lens of the eye becomes cloudy |
| closure | in Gestalt psychology the tendency to imagine the rest of an incomplete, familiar figure |
| cochlea | the snain-shaped, fluid-filled structure that contains the receptors for hearing |
| color constancy | the tendency to perceive objects as being part of the same group if they change or move in similar ways at the same time |
| conduction deafness | a hearing loss that results when the bones connected to the eardrum fail to transmit sound waves properly to the cochlea |
| cone | the type of visual receptor that is adapted for color vision, daytime vision, and detailed vision |
| continuation | in Gestalt psychology the tendency to fill in the gaps in an interrupted line |
| convergence | the degree to which the eyes turn in to focus on a close object |
| cornea | a righd, transparent structure on the surface of the eyeball |
| cutaneous senses | the skin senses, including pressure on the skin, warmth, cold, pain, vibration, movement across the skin, and stretch of the skin |
| dark adaptation | a gradual improvement in the ability to see in dim light |
| depth perception | the erception of distance, which enables us to experience the world in three dimensions |
| electormagnetic spectrum | the continuum of all the frequencies of radiated energy |
| endorphin | any of the neurotransmitters that decrease the perception of pain |
| feature detector | a neuron in the visual system of the brain that responds to the presence of a certain simple feature, such as a horizontal line |
| figure and ground | an object and its background |
| fovea | the central part of the retina that has a greater density of receptors, especially cones, than any other part of the retina |
| frequency principle | the identification of pitch by the frequency of action potentials in neurons along the basilar membrane of the cochlea, synchronized with the frequency of sound waves |
| ganglion cells | neurons in the eye that receive input from bipolar cells, which in turn receive their input from the visual receptors |
| gate theory | the proposal that pain messages must pass through a gate, probably in the spinal cord, that can block these messages |
| Gestalt psychology | an approach to psychology that seeks to explain how we perceive overall patterns |
| glaucoma | a condition characterized by increased pressure within the eyeball, resultin in damage to the optic nerve and therefore a loss of vision |
| good figure | in Gestalt psychology the tendency to perceive simple, symmetrical figures |
| hertz (Hz) | a unit of frequency representing one cycle(vibration) per second |
| hyperopia | farsightedness: the inability to focus on nearby objects |
| induced movement | a perception that an object is moving and the background is stationary when in fact the object is stationary and the background is moving |
| iris | the colored structure on the surface of the eye, surrounding the pupil |
| lens | a flexible structure that can vary its thickness to enable the eye to focus on objects a different distances |
| loudness | a perception that depends on the amplitude of a sound wave |
| monocular cues | visual cues that are just as effective withone eye as with both |
| moon illusion | the apparent difference between the size of the moon at the horizon and its size when viewed higher in the sky |
| motion parallax | the apparently swift motion of objects close to a moving observer and the apparently slow motion of objects farther away |
| myopia | nearsightedness: the inability to focus on distant objects |
| negative afterimge | a color that a person sees after staring at its opposite color for a while |
| nerve deafness | a hearing loss that results from damage to the cochlea, the hair cells, or the auditory nerve |
| olfaction | the sense of smell; the detection of chemicals in contact with the membranes inside the nose |
| opponent-process theory | the theory that we perceive color in terms of a system of paired opposites: red versus green, yellow versus blue, and white versus black |
| optic nerve | a set of axons that extend from the ganglion cells of theeye to the thalamus and several other areas of the brain |
| optical illusion | a misinterpretation of a visual stimulus as being larger or smaller, or straighter or more curved, than it really is |
| perception | the interpretation of sensory information |
| phantom limb | a continuing sensation of an amputated body part |
| pheromone | an odorous chemical, released by an animal, that changes how other members of the species respond to that animal socially |
| phi effect | the illusion of movement created when two or more stationary lights separated bya short distance flash on and off at regular intervals |
| pitch | a perception closely realted to the frequency of sound waves |
| place principle | the identification of pitch by determining which auditory neurons, coming from which part of the basilar membrane, are most active |
| presbyopia | a decreased flexibility of the lens and therefore the inability to focus on nearby objects |
| proximity | in Gestalt psychology the tendency to perceive objects that are close together as belonging to a group |
| pupil | the adjustable opening in theeye through which light enters |
| receptor | a specialized cell that converts environmental energies into signals for the nervous system |
| retina | a layer of visual receptors covering the back surface fo the eyeball |
| retinal disparity | the difference in the apparent position of an object as seen by the left and right retinas |
| retinex theory | the theory that color perception results from the cerebral cortex's comparison of vaious retinal patterns |
| reversible figure | a stimulus that you can perceive in more than one way |
| rod | the type of visual receptor that is adapted fro vision in dim light |
| sensation | the conversion of energy from the environment into a pattern of response by the nervous system |
| signal-detection theory | the study of people's tendencies to make hits, correct rejections, misses, and false alarms |
| similarity | in Gestalt psychology the tendency to perceive objects that resemble each other as belonging to a group |
| sound waves | vibrations of the air or of another medium |
| stimulus | energy in the environment that affects what we do |
| stroboscopic movement | an illusion of movement created by a rapid succession of stationary images |
| subliminal perception | the ability of a stimulus to influence our behavior even when it is presented so faintly or briefly or along with such strong distracters that we donot perceive it consciously |
| substance P | a neurotransmitter responsible for much of the transmission of pain information in the nervous system |
| taste | the sensory system that responds to chemicals on the tongue |
| taste bud | the site of the taste receptors, located in one of the folds on the surface of the tongue |
| trichromatic theory (or Young-Helmholtz theory) | theory that color vision depends on the relative rate of response of three types of cones |
| vestibular sense | a specialized sense that detects the direction of tilt and amount of acceleration of the head and the position of th head with respect to gravity |
| visual constancy | tendency to perceive objects a unchanging in shape, size, and color: despite variations in what actually reaches the retina |
| volley principle | the identification of pitch by groups of hair cells responding to each vibration by producing an action potential |
| waterfall illusion | a phenomenon in which prolonged staring at a waterfall and then looking at nearby cliffs causes theose cliffs to appear to flow upward |
