Psych Chapters 4 and 8

sensation

physical process: the experience of having your sense organs stimulated (sound waves, light waves, odorant molecules, the touches you feel)

perception

psychological process: interpreting the sensations that are experienced, to recognize meaningful objects and events (i see my car parked in the parking lot)

ambiguous images

images with multiple interpretations = same sensation with different perception

filling-in (pattern completion)

phenomena that perception goes beyond sensation (filling in information that is not there from past experiences)

sensory adaptation

diminishing sensitivity to an unchanging stimulus (when you first turn a fan on you will notice it, but after a while you stop noticing it)

transduction

converting physical into neural information

psychophysics

study of relationship between physical characteristics of stimuli (ex: intensity) and our psychological experiences of them

wavelength

long wavelengths (deep sound), short wavelengths (high pitched), amplitude gives you volume

absolute threshold

the minimum stimulation needed to detect particular stimulus 50% of the time (is the stimulus there or not?)

how low can the stimuli be to be able to notice its there (hearing test at the doctors with headphones)

signal detection theory

you have two different possibilities of the presentness of the stimuli (yes i see a stimuli or no i don’t see a stimuli)

hit

the stimulus is present and you say it’s present

miss

if the stimulus is present but you don’t detect it

false alarm

if the stimulus is absent but you say it’s present

correct rejection

if the stimulus is absent and you say it is

hit and correct rejection

what are accurate responses to the participants responses in an absolute threshold?

when background noise is high

when is signal intensity hard to understand?

experience

when you have greater exposure you’ll have a greater job at detecting signal

expectation

if there’s an expectation set, there’s a greater chance to recheck something

motivation

if a researcher gives you a stronger drive to look for something, you will be more likely to look

fatigue

need a greater amount of intensity in order to reach comfort (louder music to make you more awake)

stimuli

when you get sleep it is easier to detect what?

difference threshold (just noticeable difference, jnd)

the minimum difference a person can detect between 2 stimuli half the time (i know the stimulus is there, if it changes, do I detect the change)

weber’s law

finding that the size of a jnd is a constant fraction of the intensity of the stimulus (no major number but there is a major proportion)

all 5 senses

what are there difference thresholds for?

pupil

little black hole in the middle of your eye that allows light to enter

iris

gives your eye the color that you have, regulates the size of the pupil

light, attention, interest, and drugs

what factors influence pupils to dilate?

cornea

the clear outer covering of your eye (protects from outside stuff getting into your eye)

lens

sits behind the pupil, responsible for focusing the light, bends the light rays in process called accommodation

accommodation

changes shape of lens because the muscles are attached to it, in order to focus the light (something that’s close vs something thats far)

where the muscles around the lens alter its shape to adjust to viewing objects at different distances

retina

contains all of the photoreceptors that are found in the back of the eye (rods are strong here)

photoreceptors

in the back of the eye that detect the light (stimulus)

fovea

part of the retina that is located directly behind the pupil, the point of fixation (whatever you are directing your gaze at, that is the object that is falling here)

greatest amount of cones here

on the other parts of the retina

where does peripheral vision fall?

rods and cones

what are the two types of photoreceptors?

rods

help you see black, white, and shades of gray and gross shapes (work better at nighttime - dark adapted)

cones

help you see color and clarity (visual acuity)

need good ambient light in order to work (work best in daytime)

visual acuity

to see the details of things

rods and cones

what are the sensory neurons/input neurons for vision?

rods and cones to bipolar cells to the ganglion cells

what is the order of visual perception?

the axons of the ganglion cells

what comes together to make up the optic nerve?

blind spot

the part of the eye where the optic nerve leaves (no rods or cones) no stimulation

your brain fills in the gap

nearsightedness

the lens focuses the image in front of the retina (uncorrected)

in nearsightedness

with a minus lens for correction, the image focuses directly on the retina (corrected)

farsightedness

the lens focuses the image past the retina (uncorrected)

in farsightedness

with a plus lens for correction, the image focuses directly on the retina (corrected)

right

information from your left visual field, falls on which side of your eye?

from the retina then along the optic nerve

where does information travel in the eye?

optic chiasm

the crossover point in the brain where the switch of images from the retina to the optic track of the other side

the thalamus (the lateral geniculate nucleus - LGN)

where does information end up after the crossing the optic chiasm?

goes into the visual cortex in the occipital lobe

where does information go after it reaches the thalamus?

feature detectors

neurons in visual cortex that analyze the retinal image and respond to specific aspects of shapes (ex: angles and movements)

feature detectors combine and fire at the same time

how do you see certain images?

simple cells

respond to a bar of light oriented at a particular angle

complex cells

get input from many simple cells, receptive to movement

hypercomplex cells

input from many complex cells, respond to patterns

an image is created

what happens when you combine simple, complex, and hypercomplex cells?

wavelength

corresponds to the hue/color you see

blue and lighter colors

shorter wavelengths =

reds and oranges

longer wavelengths =

amplitude

corresponds to brightness

bright

high amplitude =

dull

low amplitude =

blue, green, and red

what colors can humans see (trichromat)

blues and greens

what colors can dogs see (dichromat)

they are tetrachromat meaning they can see more colors at a time

why are birds and other animals different from humans when seeing?

trichromatic color theory

theory that all color that we experience results from mixing three colors of light (red, green, and blue)

it cannot explain various colorblind problems (people can’t see red or green but can still see yellow?)

what is the problem with the trichromatic color theory?

afterimages

when you stare at one image for so long and switch to another image, your neurons overshoot to see the opposite colors

opponent process theory

color vision results from cones linked together in three pairs of opposing colors, so activation of one member of the pair inhibits activity of the other

red-green

yellow-blue

white-black

what are the opposing colors in the opponent process theory?

color processing of cones in retina

what does the trichromatic theory explain?

LGN and visual cortex process color information

what does the opponent process theory explain?

color blindness

weakness or deficiency in perception of certain colors

binocular cues

depth cues that result from the use of both eyes

retinal disparity

compare images from retinas of both eyes. greater disparity means object is closer (if images coming into the eyes is very different it means that the object is closer to you)

binocular convergence

information about how much eyes must rotate inward to look at an object. more rotation means object is closer

binocular

what cue is retinal disparity and binocular cues part of?

monocular cues

depth cues that are available to each eye separately

linear perspective

lines that are parallel seem to converge on a vanishing point as they move further away

texture gradient

objects that are closer to you it’s easier to pick out individual objects and you can see the features of them more clearly (objects that are further away, they all blur together)

atmospheric perspective

objects that are further away take on a purply/bluish hue to them and they appear hazier (not as clear)

interposition

whether you can see the whole object or not, objects that are closer will block objects that are farther away (if it’s closer you will see the whole thing)

monocular

what cue is linear perspective, texture gradient, atmospheric perspective, and interposition part of?

size illusions

using previous knowledge to make it look like one’s bigger than the other

perceptual constancy

perceiving objects as unchanging even as the image on the retina changes

size constancy

you perceive an object as being the same size even though the image on your retina grows or shrinks (ames room)

shape constancy

you understand that the shape of objects does not change even though the image on your retina changes

lightness constancy

objects seem to have constant lightness even when illumination varies

relative luminance

amount of light an object reflects relative to its surroundings

color constancy

perceiving familiar objects as having constant color even when changing illumination alters reflected wavelengths

gestalt

an organized whole (the whole is different than some of its parts)

if you look at bits and pieces it’s random on a page, but if you organize them, you can see some shapes

form, pattern, or shape

similarity

taking like images and grouping them together

continuity

it is similar to perceive things as continuous (not broken into pieces)

proximity

things that are nearer to each other are grouped together

closure

you will perceive lines and edges even when they are not physically present

figure-ground

organization of visual field into its objects (figures) and surroundings (ground)

if you are looking at a screen, that becomes the figure, and the surrounding environment becomes the ground

iris

cornea

lens