ch 6 sensation and perception

sensation

process which sensory receptors and nervous system receive and represent stimulus energies from the environment (i.e. light, sound, temperature, pressure, etc.)

sensory receptors

sensory nerve that responds to stimuli

perception

process of organizing and interpreting sensory info and enabling us to recognize meaningful objects and events

bottom-up processing

analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information,

top-down processing

information processing guided by higher-level mental processes as when we construct perceptions drawing on our experiences and expectations

Transduction

conversion of one form of energy into another; In sensation, the transformation of stimulus energies (sight, sound, taste) into neural impulses the brain can interpret

Psychophysics

studies that relationships between the physical energy we detect and its effect on our psychological experiences

Signal detection theory

Predicts how and when we will detect a faint stimulus amid background noise

Individual absolute threshold

vary depending on the strength of the signal and on our experiences, expectation, motivation, and alertness

What is Absolute threshold

Minimum stimulation to detect a particular stimulus 50% of the time (i.e. a bug is on you and you don’t notice.)

when your absolute threshold is low that means

you can hear more stuff

subliminal

input below the absolute threshold for conscious awareness (less aware)

priming

Activating (often unconsciously) associations in our mind setting us up to perceive, remember, or respond to objects or events in certain ways (i.e. primed to hear a baby cry because of past experience with your own crying baby.)

difference threshold (just noticeable difference)

minimum difference a person can detect between 2 stimulus half the time; increased with stimulus size (i.e. Musicians can hear the pitch of different notes when they tune their instruments OR you taste a slight difference in the food you eat)

Weber’s Law

Mathematical explanation; For an average person to perceive a difference, 2 stimuli must differ by a constant minimum percentage NOT a constant amount; exact proportion varies depending on the stimulus. (i.e. lifting weights. Average person will feel difference of 5lb to 10 lb. But a body builder will not. So they must lift a 50lbs. and a 100lbs. to feel difference threshold)

subliminal stimuli

stimuli too weak to detect 50% of the time

subliminal sensation

sensation that is too fleeting to enable exploitation with subliminal message (i.e. “feeling” the ghost of your grandma)

subliminal persuassion

may produce a fleeting subtle but not powerful enduring effect on behavior (discovered by GREENWALD)

SENSORY ADAPTATION

When our sensory receptors get overworked and diminish (i.e. used to smell of house or your body odor; eye adjust to eyelashes because your micromovements of the eyes are constantly moving)

emotion adaptation

the face in the middle is a combined face of the two images. You think the woman is scared bc you are used to seeing an angry face (DISCOVERED BY BUTLER)

PERCEPTUAL SET

a mental predisposition/bias perceived one thing and not the others; This is developed from our schema which organize and interpret unfamiliar info through experience. This includes top-down processing, ambiguous sensation interpretation, including gender stereotypes. (i.e. when looking at a weird picture, you see the Loch Ness monster; when you eat something and it matches to schema of “good” food )

wavelength

distance from peak of light to another peak. electromagnetic wavelengths pulse from short blips of cosmic rays (CAN BE LIGHT OR SOUND)

Hue

dimension of color that is determined by wavelength

Intensity

Amount of Energy in a light wave or south wave which influences the brightness or loudness; this is determined by amplitude

wavelength is to ___________; intensity is to _____________

hue; brightness/loudness

Retina

light-sensitive inner surface of the eye that contains receptor rods and cones plus layers of neurons that process visual info

ACCOMODATION

the process which the eye’s lens change shape to focus on far and near objects (different than ch.5 accommodation about creating complex schemas)

frequency

number of wavelengths

amplitude

height of peak to trough (top to bottom)

Short wavelength

high frequency (bluish colors) - Just like Smurfs

Long Wavelengths

low frequency (reddish colors) - Just Like Clifford

when do eyes dilate

during sympathetic nervous system

cornea

clear covering of the eyeball that protects it

pupil

opening of the eyeball that dilates/contracts for light; this can changes based on eye color

iris

colored part of the eye that changes the pupil’s shape

lens

refract/focuses the light to back of the eyeball

RETINA

innermost layer of back of the eyeball that contains receptor cells; this is the place where transduction occurs

Fovea

The center of the eyeball on the retina where vision is the clearest; POINT OF CENTRAL FOCUS

Optic nerve

where nerve impulses from eyeball go to the brain

blind spot

part of the eyeball with no receptor cells

first layer of retina

rods and cones where conduction occurs

second layer of retina

pathway for nerve impulses where the bipolar cells are

third layer or retina

location of ganglion cells; they have long axons that create optic nerve that transmits to the thalamus

rods

sensitive to faint light and located mostly in the periphery of the retina; have greater numbers than cones

cones

help to see well in lit areas and detect color + details; concentrated at the fovea but are less in numbers compared to rods

optic nerves from both eyes cross ___________________ so info goes to both sides of the thalamus in order to enter the ________________

optic chiasm; visual cortex

Young-Helmholtz Trichromatic Theory

3 color systems (red, green, blue); each respond to varying degrees of different color stimuli; when these systems don’t work you get color blind

how does vision work

Light enters the eye through the pupil, refracting light on the lens, that will hit the retina. This contains rods and cones that transduce the light into neural impulses that will pass the optic nerve to enter the visual cortex by crossing the optic chiasm. The brain conducts parallel processing and creates the image involves color, depth, form, and movement.

issues of vision

color blindness, blindness/injury, eyeball lost/severe optic nerve, near and far sightedness (inflexible lens)

no cones systems work

monochromatic

red-green blindness

green cone system isn’t functional. Become dichromats where you see only 2 color systems

Herring’s opponent process theory

opposing retinal processes enable color vision (red+green, blue+orange, white+black)

ex) red system gets fatigued for long period of transduction so they activate green system

afterimage effect

continuation of a visual sensation even after the visual stimulus is removed (ex: you see the British Flag)

Feature detectors

specialized nerve cells in the brain that respond to stimulus such as shapes, angles, or movement

Hubel and Wiesel found

there are specific sectors of the brain that process different visual cues; The brain deconstructs and then reassembles visual images

ex) the visual cortex is damaged but different cortex of the brain is active and can see specific visual features like movement or shape

Parallel Processing

Brain processes everything at once which is used in the Atkinson-Shiffrin model; processes motion, form, depth, and color

gestalt psychology

specialize in perceptual organization based off psychologist Gestalt. Principles used to organize sensations into perception such as form, depth, and constancy.

People tend to organize pieces of information into an organized whole aka

a gestalt

example that demonstrates gestalt

Necker Cube - example of closure

figure-ground relationship

organize the visual field into objects that stand out from their surrounding

ex) figure is the melody while ground is the background music like bass or the beat

grouping

perceptual tendency to organize stimuli into meaningful groups

proximity

grouping based on physical closeness

similarity

grouping based on similar of objects

continuity

grouping based on lines or curves that continue as part of the original object

Closure

mind tends to ignore gaps and instead complete objects

depth perception

The ability to see objects in 3D although the images that strike the retina are 2D.

experiment that tested depth perception in babies where they did not crawl off _________ because they see the depth

The Visual Cliff.

Binocular cues

a cue that use both eyes to send to the brain; retinal disparity and convergence

retinal disparity

calculated distance that is compared by the two eyes to make one image. the fact that the left and right fields of vision provide slightly different visual images when focusing on a single object.

ex) see close object in focus, but background is blurry from both retinas

Convergence

way eyes strain inward to see an object

ex) cross eye signals that its really close, more crossing means its closer

monocular cue

a depth cue available to one eye alone. relative size, relative height, interposition, linear perspective.

interposition

when an object obscures another, we perceive it to be in front; also occlusion

relative size

if similar objects exist, smaller ones are assumed to be further away

relative height

objects higher in an image appear to be further away from the viewer than objects lower in the image; comparing the height of proportion

linear perspective

parallel lines extending in the distance appear to be converging

motion perception

humans are imperfect at motion perception; when large and small objects move at the same speed, the large objects tend to appear to move more slowly; ex) airplane looks like more slow bc it’s so big, and far away

Phi phenomenon

an illusion of movement created when two or more adjacent lights blink on and off in quick succession ex) las vegas

Perceptual constancy

objects are perceived as unchanging such as color, brightness, shape and size

ex) you were a green shirt. the lights in a room turn off. The perception is a different shade of color but it is still the same.

color constancy

colors are the same even though illumination dims

relative luminance

shadows; The amount of light a objects reflects on its surroundings

perceptual adaptation

ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field

ex) professor wears upside down glasses after a couple of days he got used to it

perceptual adaptation vs. sensory adaptation

perceptual adaptation = changing brain perception (longer)

sensory adaption = sensory receptors get used to a stimuli such as smells (these are short)

hearing is known as

audition

sound waves

from the environment into the brain; sound waves compress and expand air molecules and the ears detect these brief pressure changes; does not occur in outer space

fast wave is _______ as slow wave is _________

high pitch; low pitch

human ears detect these changes in air pressure and transform them into ___________________ which the brain decodes as sound

neural impulses

Pinna

catches the sound wave (outer ear)

auditory canal

sends sound waves towards the ear drum

eardrum

tympanic membrane = sends vibrations from soundwaves to middle ear; if it gets red and swollen it may be infected

hammer, anvil, sitrup are

ossicles aka malleus, incus, and stapes = sends vibrations to cochlea

oval window

connection point for stirrup to cochlea = goes straight from bones to specific structure

auditory nerve

sends neural impulses to brain/auditory cortex

cochlea

where transduction occurs in the ear

basilar membrane

part of cochlea where cilia are located

cilia

hairs in cochlea on basilar membrane where they move with fluid; RECEPTRO cells that transduce sound to neural impulse

inside the cochlea

stimulate that hair cells (cilia) on the basilar membrane where transduction occurs

process of hearing in the ear

Sound wave is collected by the pinna and moves through the auditory canal that sends vibrations to eardrum (tympanic membrane). These waves are moved through the ossicles (malleus, incus, stapes) that transfer vibrations to the oval window to make its way to the cochlea. Inside the cochlea, the basilar membrane has cilia (hair cells) that are receptor cells that transduce the waves into neural impulses. These impulses then go through the auditory nerve in order to reach to brain for identification and comprehension.

tinnitus

the ringing in the ear; doesn’t have an external source

sensorineural hearing loss

nerve deafness - damage to cell receptors (cilia) or associated to nerves

conduction hearing loss

damage to the mechanical systems that conduct sound waves to the cochlea such as the ossicles