Unit 5: Sensation and Perception

the relationship between physical stimuli and our psychological reaction to them

any detectable input from the environment

an edge or a boundary

the detection of physical stimuli and the transmission of this information to the brain

the processing, organization, and interpretation of sensory signals in the brain

the interpretation of sensory information based on knowledge, expectations, and past experiences

perception based on the physical features of the stimulus

the process by which sensory stimuli are converted into neural signals the brain can interpret

the minimum intensity of stimulation necessary to detect a sensation half the time

the minimum amount of change required to detect a difference between two stimuli

the theory that to perceive a difference between two stimuli, they must differ by a constant percentage and not an amount; the more intense the original stimulus is, the more change is needed to notice a difference

a theory of perception based on the idea that the detection of a stimulus requires a judgment - it is not an all-or-nothing process

• hit - true positive

• miss - false negative

• false alarm - false positive

• correct rejection - true negative

registration of sensory input without conscious awareness (below absolute threshold); weak, all effects “observed” most likely placebo

a decrease in sensitivity to a constant level of stimulation

a condition in which affected people experience unusual combinations of sensations

most information is taken through vision, the dominant sense

• brightness - determined by amplitude of light wave

• purity - saturation

• hue/color - determined by wavelength of light wave, ROY G. BIV

cornea, pupil, iris, lens, retina, fovea

clear, curved bulge on the front of the eyeball; focuses light by bending it towards a central focal point; protects the eye

the adjustable opening in the center of the eye, controls amount of light entering the eye; brighter conditions → iris expanding → pupil contracting, less light let in

ring of muscle tissue that forms the colored portion of the eye; regulates the size of the pupil by changing its size

a transparent structure behind the pupil in the eye that changes shape to focus images on the retina

curvature of the lens adjusting to alter visual focus, focus on close object - lens gets fatter, focus on distant object - lens flattens out*

the thin inner surface of the back of the eyeball, which contains the sensory receptors that transduce light into neural signals, made of three layers of cells:

• receptor cells - specialized cells converting energy into action potential

  • rods - retinal cells that respond to low levels of light and result in black-and-white perception

  • cones - retinal cells that respond to higher levels of light and result in color perception

• bipolar cells - middle layer in the retina, transfers information from receptor cells to ganglion cells

• ganglion cells - innermost layer of retina

optic disc; no rods and cones at a point where the optic nerve travels through the retina to exit the eye

the center of the retina, where cones are densely packed and vision is the best/most detailed

retinal cells that respond to low levels of light and result in black-and-white perception

Young and Heimholtz’s theory that any color can be created by combining light waves of red, green, and blue

theory of color vision that says color is processed by cones in opponent pairs: red-green, yellow-blue, black-white

a condition in which affected people lack one of the three types of cones

the organization of the visual field into objects (figures) that stand out from their surroundings (ground)

correctly perceiving objects as constant, despite raw sensory data that could mislead perception; size constancy, shape constancy, light/brightness constancy, space constancy, color constancy

cues of depth perception that arise from the fact that people have two eyes

because of the distance between the two eyes, each eye receives a slightly different retinal image

when a person views a nearby object, the eye muscles turn the eye inward

cues of depth perception that are available to each eye alone

observed when moving relative to objects, in which the objects that are closer appear to move faster than the objects that are farther

sense of hearing; sound perception

perception of balance determined by receptors in the inner ear

sense of taste

sensory organs in the mouth that contain the receptors for taste

sense of smell

the brain center for smell, located below the frontal lobe

the gate to pain perception can be closed or occupied if other stimuli are processed simultaneously

nerve cells in the visual cortex that respond to specific features

a movement by psychologists, the whole is greater than the sum of its parts

symmetry, proximity, similarity, continuity, closure

people’s tendency to perceive that the movement of an object continues once it appears to move

people tend to fill in gaps in a perceptual field

illusion of movement created when two or more adjacent lights blink on and off in succession

the ability to see in 3D and judge dimensions

tests depth perception in infants and young animals, suggests that depth perception is inborn

misinterpreting sensory stimuli; ex. impossible figures, reversible figures, Muller-Lyer illusions (one line seems longer than the other)

visual ability to adjust to an artificially displaced visual field

mental predisposition to perceive something one way

• loudness - measured in decibels, determined by sound wave amplitude

• pitch - determined by sound wave frequency/wavelength

• purity/timbre - what makes a particular sound unique from another*

we hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane

we sense pitch by hair cells in the basilar membrane that vibrate at the same rate as the sound wave

hair cells cannot vibrate at certain speeds, but groups of nerve fibers can fire impulses in rapid succession; volley of impulses

in charge of air conduction

• pinna - a sound-collecting cone in the outer ear

• auditory canal - the opening through which sound waves travel as they move into the ear for processing

bone conduction

• tympanic membrane/eardrum - transfers sound vibration from the air to the tiny bones of the middle ear

• ossicles - malleus, incus, stapes (hammer, anvil, stirrup)

• oval window - point on the surface of the cochlea which receives the sound vibrations from ossicles

fluid conduction

• eustachian tube

• cochlea - major organ of hearing

  • basilar membrane holds sound receptor cells and runs the length of the spiraled cochlea

  • cilia - receptor cells hairs for hearing located in the cochlea

• auditory nerve - carries sound information to the temporal lobes of the brain

organs in the inner ear used in sensing body orientation and balance (vestibular sense)

caused by damage to the mechanical system that conducts sound; ex. punctured eardrum

caused by damage to the cochlea’s receptor cells or to auditory nerves; can be caused by aging or prolonged loud noise