sensation
detection of external physical stimulus and the transmission of info about this stimulus to the brain
perception
the processing, organizing, and interpretation of sensory signals in the brain; these processes result in an internal neural representation of the physical stimulus
sensory receptors
sensory organs that detect physical stimulation from the world and change that stimulation into info that can be processed by the brain
transduction
a process by which sensory receptors change physical stimuli into signals that are eventually sent to the brain
absolute threshold
the smallest amount of physical stimulation required to detect a sensory input half the time it is present
difference threshold
the minimum difference in physical stimulation required to detect a difference between sensory inputs
signal detection theory
detection of a faint stimulus requires judgment-it is not an all-or-none process
sensory adaptation
a decrease in sensitivity to a constant level of stimulation
lens
the adjustable, transparent structure behind the pupil; this structure focuses light on the retina, resulting in a crisp visual image
retina
the thin inner surface on back of eyeball; this surface contains the sensory receptors
rods
sensory receptors in the retina that detect light waves and transduce them into signals that are processed in the brain as vision. They respond best to low levels of illumination, and therefore they do not support color vision or seeing fine detail.
cones
sensory receptors in the retina that detect light waves and transduce them into signals that are processed in the brain as vision. They respond best to higher levels of illumination, and therefore are responsible for seeing color and fine detail.
trichromatic theory
there are three types of cone receptor cells in the retina that are responsible for color reception. Each type responds optimally to different, but overlapping, ranges of wavelengths.
opponent-process theory
the proposal that ganglion cells in the retina receive excitatory input from one type of cone and inhibitory input from another type of cone, creating the perception that some colors are opposites
grouping
the visual system's organization of features and regions to create the perception of a whole, unified object
bottom-up processing
the perception of objects is due to analysis of environmental stimulus input by sensory receptors; this analysis then influences the more complex, conceptual processing of that information in the brain, patterns
top-down processing
the perception of objects is due to the complex analysis of prior experiences and expectations within the brain; this analysis influences how sensory receptors process stimulus input from the environment
binocular depth cues
cues of depth perception that arise because people have two eyes (binocular disparity)
monocular depth cues
cues of depth perception that are available to each eye alone (occlusion, height in field, relative size, familiar size, linear perspective, texture gradient)
occlusion
a near object blocks an object that is farther away
height in field
objects that are lower in the visual field are seen as nearer than objects that are higher in the visual field
relative size
objects that are farther away project a smaller retinal image that close objects of similar size
familiar size
we know how large familiar objects are, so we can estimate how far away they are by the size of their retinal images
linear perspective
seemingly parallel lines appear to converge in distance
texture gradient
as a uniformly textured surface recedes, its texture continuously becomes denser
eardrum
a thin membrane that marks the beginning of the middle ear; sound waves cause it to vibrate
cochlea
a coiled, bony, fluid-filled tube in the inner ear that houses the sensory receptors
hair cells
in cochlea; detect sound waves and transduce them into signals that are processed as sound
temporal coding
the perception of lower-pitched sounds is a result of the rate at which hair cells are stipulated by sound waves of lower frequencies
place coding
the perception higher-pitched sound is a result of the location on the basilar membrane where hair cells are stimulated by sound waves of varying higher frequencies
taste buds
structures on tongue that contains the sensory receptors called taste receptors
papillae
structures on the tongue that contain taste buds
olfactory epithelium
a thin layer of tissue, deep within the nasal cavity, containing the olfactory receptors; these sensory receptors produce information that is processed in the brain as smell
olfactory bulb
brain structure above the epithelium in the nasal cavity; from this structure, the olfactory nerve carries information about smell to the brain
pressure receptors
detect tactile stimulation and transduce it into information processed as different typed of pressure on the skin
fast fibers
sensory receptors in skin, muscles, organs, and membranes around both bones and joints; these myelinated fibers quickly convey intense sensory input to the brain, where it is perceived as sharp, immediate pain
slow fibers
sensory receptors in skin, muscles, organs, and membranes around both bones and joints; the unmyelinated fibers slowly convey intense sensory input to the brain, where it is perceived as chronic, dull, steady pain