psych unit 3: sensation and perception

sensation

the stimulation of sensory receptors, info sent to brain

perception

concious experience of the enviornment

illusion

when sensation and perception DONT MATCH

bottom-up processing

Processing that starts with information received by the receptors. This type of processing is also called data-based processing.

top-down processing

the use of preexisting knowledge to organize individual features into a unified whole

steps from sensation to perception

detect stimuli,transduction, send to brain to organize

Transduction

transforming physical energy into neural impulses in receptors which can then be sent to the brain to be processed

cornea

-the transparent outer covering of the eye

-protects you from dust and foreign objects

-80% of light is focused through the cornea

iris

colored muscle that changes shape to let light into the pupil.

Pupil isn't actaully changing shape, your iris is

lens

-focuses 20% of light

-changes shape depending on if you need to see close or far

accomodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

Presbyopia

the lens stifens over time, making it hard to see at different distances

fovea

the central focal point in the retina, around which the eye's cones cluster

transduction in the eyes

1. first light goes past the rows of other cells to the rods and cones in the back

2. occurs in the rods and cones, where light waves become neural impulses

3. Neural impulse goes back through cells to ganglion cells

4. travels from ganglion to optic nerve, then to the visual cortex(in the occiptital lobe)

blind spot

the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there

convergence

Several rods combine together and converge onto a gangleion cell.

Ex: if a ganglion cell needs 10 units to fire but its dim and the cones are only getting 3 units each, it won't fire. However, 2 units per rod combined will get a ganglion cell to fire

properties of cones

Color, visual acuity(better at seeing details), located in the fovea

properties of rods

more sensitive to dim lighting, periphery

attention is:

the glue that binds things together

conjunction search

search for a target defined by the presence of two or more attributes

trichromatic theory

-3 cones sensitive to different wavelengths

-s cones fire for shorter wavelengths, l cones for longer

- if multiple cones are activated you will perceive the combo of their activation

opponent process theory

in additon to our rods and cones, further in the visual cortex, we have opponent cells. If one is firing it negates the other.

ex: when yellow fires it inhibits the blue

after image

if we stare at a color to long and then at white. The cells of the color we just looked at get tired and we only see its complementary color

color blindness

trait found on x chromosome when you are missing the M cone or its not functioning properly

monocular cues

depth cues available to either eye alone

texture gradient

things appear more closely packed in the distance

relative size

if something in a photo is bigger, it appears closer to you

relative height

if something is farther it appears closer to the horizan

linear perspective

as parallel lines extend into the distance, they appear to meet together

occlusion

if an object is blocking something then it appears closer

binocular cues

depth cues, such as retinal disparity,that depend on the use of two eyes

retinal disparity

a binocular cue for perceiving depth by comparing images from the retinas in the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.

structuralists

believe you cannot perceive something that isn't there because perception arises from sensation

Gestalt Psychology

disagrees with structuralists because they believe in an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.

max berheimer

one of the first gestalt psychologists who discovered phi movement: the illusion that lights that are actually stationary seem to be moving

Gestalt Principles

Describe the top-down processing that organizes sensory information into distinct forms.

continuity,closure,simmilarity,proximity,figure, common fate

continuity

we perceive smooth, continuous patterns rather than discontinuous ones

Closure

the tendency to complete figures that are incomplete

similarity

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

proximity

more likely to group things that are closer together

figure

the perception of figures against a background

common fate

the tendency to perceive objects that are moving together as belonging together

dogs are __________ times more sensative to smell than humans

10,000

olfactory epithelium

400 types of olfactory receptors found in the back of the nasal cavity

The infinite smells we detect are made up of_______

different odorants that can be detected by many different receptors

women have_____ percent ________ neurons in their olfactory bulb than men

50,more

linguistic variation

explains why some cultures have more words to describe specific scents than other

chemical senses

smell and taste because receptors are detecting specific chemicals

Papillae

bumps on our tongue where taste buds lie between

taste buds

receptor cells for taste where transduction occurs

supertaster

has more than 35 paplilae in a hole punch

nontaster

has less than 15 papilae in a hole punch circle. Correlation with smoking and obesity

somatic senses

also known as tactile senses: touch, pressure, temperature, pain. controlled by motor cortex and sensory cortex.

haptic receptors

in our skin all over our body that respond to temperature,pressure,and pain

endorphins

natural, opiate-like neurotransmitters linked to pain control and to pleasure

horopter

An imaginary surface that passes through the point of fixation. Images caused by a visual stimulus on this surface fall on corresponding points on the two retinas.

cortical magnification

The amount of cortical area (usually specified in millimeters) devoted to a specific region (e.g., 1 degree) in the visual field.

crossed disparity

image is closer than the horopter so images move to the temporal side

uncrossed disparity

The sign of disparity created by objects further than the horopter. image moves to nasal portion of eyes

3d glasses and depth perception