Unit 1.2 Sensation and Perception

sensation

sensation

the process that occurs when special receptors in the sense organs are activated, allowing various forms of outside stimuli to become neural signals in the brain

transduction

the process of converting outside stimuli, such as light, into neural activity

synesthesia

disorder in which the signals from the various sensory organs are processed in the wrong cortical areas, resulting in the sense information being interpreted as more than one sensation

Just Noticeable Difference or Difference threshold

the smallest difference between two stimuli that is detectable 50 percent of the time

absolute threshold

the lowest level of stimulation that a person can consciously detect 50 percent of the time the stimulation is present

sensory adaptation

tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging

brightness

determined by the amplitude of the wave

color/hue

determined by the length of the wave

saturation

refers to the purity of the color

What is the correct order of light passing through the eye?

cornea-iris controls the pupil-lens-retina where its transformed into nerve impulses-optic nerve

cornea

bends light waves so the image can be focused on the retina

iris

muscles control the size of the pupil

pupil

iris opening that changes size depending on the amount of light in the environment

lens

changes shape to bring objects into focus

retina

contains photoreceptor cells

fovea

central area of retina; greatest density of photoreceptors

optic nerve

sends visual information to the brain

blind spot

where the optic nerve leaves the eye; there are no photoreceptor cells here

visual accomadation

the change in thickness of the lens as the eye focuses on objects that are far away or close

rods

visual sensory receptors found at the back of the retina, responsible for color vision and sharpness off vision

blind spot

area in the retina where the axons of the three layers of retinal cells exit the eye too form the optic nerve, insensitive to light

dark adaptation

the recovery of the eye's sensitivity to visual stimuli in darkness after exposure to bright lights

light adaptation

the recovery of the eye's sensitivity to visual stimuli in light after exposure to darkness

trichromatic theory

theory of color vision that proposed three types of cones: red, blue, and green

after images

images that occur when a visual sensation persists for a brief time even after the original stimulus is removed

opponent-process theory

theory of color vision that proposes four primary colors with cones arranges in pairs: red-green and blue-yellow

monochrome color blindness

where people have either no cones or have cones that are not working at all- shades of grey

hertz (Hz)

cycles or waves per second, a measurement of frequency; wavelengths are interpreted as pitch where amplitude is interpreted as volume

auditory canal

short tunnel that runs from the pinna to the eardrum

cochlea

snail-shaped structure of the inner ear that is filled with fluid

auditory nerve

bundle of axons from the hair cells in the inner ear

What is the order of sound through the ear?

Sound enters through the pinna and vibrates the eardrum, which then vibrates the hammer, anvil, and stirrup, which in turn vibrate the oval window. This causes the fluid in the cochlea to vibrate, which vibrates the basilar membrane, which then causes the organ of Corti to move up and bend its hair cells, which send signals about hearing to the brain.

pitch

psychological experience of sound that corresponds to the frequency of the sound waves; higher frequencies are perceived as higher pitches

place theory

theory of pitch that states that different pitches are experienced by the stimulation of hair cells in different locations on the organ of Corti

frequency theory

theory of pitch that states that pitch is related to the speed of vibrations in the basilar membrane

volley principle

theory of pitch that states that frequencies from about 400 Hz to 4000 Hz cause the hair cells (auditory neurons) to fire in a volley pattern, or take turns in firing

gustation

the sensation of a taste

What are the five taste sensations

Sweet, salty, bitter, sour, umami, oleogustus

olfaction (olfactory sense)

the sensation of smell

olfactory receptor cells

each have about a dozen little hairs, or cilia

Where do olfactory receptors go in the brain?

olfactory bulbs

olfactory bulbs

areas of the brain located just above the sinus cavity and just below the frontal lobes that receive information from the olfactory receptor cells

touch senses

the sensations of touch, pressure, temperature, and pain.

kinesthetic sense

sense of the location of body parts in relation to the ground and each other

vestibular senses

the sensations of movement, balance, and body position; innermost chamber of the ear

perception

the method by which the sensations experienced at any given moment are interpreted and organized in some meaningful fashion

size constancy

the tendency to interpret an object as always being the same actual size, regardless of its distance.

shape constancy

the tendency to interpret the shape of an object as being constant even when its shape changes on the retina

brightness constancy

the tendency to perceive the apparent brightness of an object as the same even when the light conditions change

figure-ground

the tendency to perceive objects, or figures, as existing on a background

reversible figures

visual illusions in which the figure and ground can be reversed

proximity

the tendency to perceive objects that are close to each other as part of the same grouping

similarity

the tendency to perceive things that look similar to each other as being part of the same group

closure

the tendency to complete figures that are incomplete

continuity

the tendency to perceive things as simply as possible with a continuous pattern rather than with a complex, broken-up pattern

contiguity

the tendency to perceive two things that happen close together in time as being related

depth perception

the ability to perceive the world in three dimensions

monocular cues (pictorial depth cues)

cues for perceiving depth based on one eye only

binocular cues

cues for perceiving depth based on both etes

linear perspective

the tendency for parallel lines to appear to converge on each other

relative size

perception that occurs when objects that a person expects to be a certain size appear to be small and are, therefore, assumed to be much farther away

Interposition

the assumption that an object that appears to be blocking part of another object is in front of the second object and closer to the viewer

aerial perspective

the haziness that surrounds objects that are farther away from the viewer, causing the distance to be perceived as greater

texture gradient

the tendency for textured surfaces to appear to become smaller and finer as distance from the viewer icreases

motion parallax

the perception of motion of objects in which close objects appear to move more quickly than objects that are farther away

accommodation

as a monocular clue, the brain's use of information about the changing thickness of the lens of the eye in response to looking at objects that are close or far away; also a muscular cue

convergence-bi

the rotation of the two eyes in their sockets to focus on a single object, resulting in greater convergence for closer objects and lesser convergence if objects are distant; also a muscular cue

binocular disparity

the difference in images between the two eyes, which is greater for objects that are close and smaller for distant objects

Muller-Lyer illusion

illusion of line length that is distorted by inward-turning or outward-turning corners on the ends of the lines, causing lines of equal length to appear to be different

perceptual set (expectancy)

the tendency to perceive things a certain way because previous experiences or expectations influence those perceptions

top-down processing

the use of pre-existing knowledge to organize individual features into a unified whole

bottom-up processing

the analysis of the smaller features to build up to a complete perception

ganglion cells

their axons form the optic nerve

Supertaster

person with a higher than average number of taste buds

Medium taster

average number of taste buds and tastes PROP at an average level

Nontaster

having the fewest taste buds, tolerate many somewhat bitter foods

gate-control theory

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.

Phantom Limb Syndrome

the perception of sensations, including pain, in a limb that has been amputated

semicicular canals

3 bony fliud-filled loops help maintain balance