S&P Exam 3

what is the degree of the horizontal visual field

180

what is the degree of the vertical visual field

140

where is the left visual field located and processed

it is on the left side of the body but processed in the right side of the brain

if there was a ball coming from the left of you where will it be projected in your brain

will be projected onto the left eye nasal retina and the right temporal retina

what is the pathway of the nasal retina

they cross over to the other side of the brain

what is the pathway of the temporal retina

they stay on the same side

where is the left visual field projected to

the right hemisphere

where is the right visual field projected to

the left hemisphere

how are the nasal retina visual pathways processed

contralaterally

• they are the only ones

• they cross over to the other side

how are the temporal retina visual pathways processed

ipsilaterally

• they stay on the same side

where does the cross over of the nasal retina pathways occur

the optic chiasm(a)

• the fibers cross and form an x

• this ONLY happens with the nasal retinas

where does all of the visual pathways happen

• the back of the brain - occipital lobe

• there is a subcortical pathway that flows from the eye to the occipital lobe

what do the superior and inferior colliculus do

• they control and direct the movement of the eyes

• they act as the subcortical weigh stations for the eye

• its a WHERE kind of thing - where is the object

• the information comes in here and then passes on

where does 20% of all things coming in from the eyes go

the superior colliculus

what are some facts about the superior colliculus

• it is the oldest part of the brain

• some lower animals have functioning that ends here

what is the function of the superior colliculus

• it controls eye movement

  • directing

  • guiding

• helps with visual and ocular reflexes

when do the neurons of the superior colliculus fire

• sometimes they fire before the movement

  • almost as if the intention matters

what did jay and sparks study

they found that the cells respond to auditory stimulus

• they migrated from the inferior colliculus

• how much the auditory cell fires depends on if you’re looking at the source or not

  • they fire until you are looking at the sound source

where is the lateral geniculate nucleus (LGN)

there is one for each hemisphere

how many projections from the eye go to the LGN

80%

how many layers make up the LGN

6 layers

• layers 1-2 are magnocellular

• layers 3-6 are parvocellular

• three layers get input from the left eye and the other three layers get input from the right eye

what is cortical magnification

70% - 80% of detail is received from the fovea

what is the LGN all about

its like stating a jigsaw puzzle

• corners, edges, emphasizes color, and theres a motion aspect

• the layers that get information from m cells have characteristics that mimic m cells

• the layers that get information from p cells have characteristics that mimic p cells

• its a WHAT kind of thing - what is the object

where does the majority of the input come from for the LGN

the brain

• most likely the primary visual cortex

what is the reticular activation system and give an example

• it feeds into the LGN

• it deals with arousal

• it acts as volume control

• ex: fight or flight - pupils dilate to get more information

who was Gerald Schneider

a researcher who studied Syrian hamsters

• wanted to investigate if the midbrain was involved with eye movements

why did Schneider study hamsters

• because they do not have fully developed brains at birth

  • he didnt have to cut around a cortex to study the midbrain

• they have a large appetite for sunflower seeds

  • this gives more practical reasoning

  • with animal research the best motivation is hunger

    • ex: 2 doors, one with food the other without food

  • you want the hamster with an appetite

describe the table of Schneiders study

what did Holmes and another doctor study

soldiers in WWII

• soldiers had trouble identifying where objects are after receiving injuries to the brain

what is another way to say the two visual system hypothesis

2 different models of processing pathways

what information did Schneider find as evidence for the 2 different types of visual pathways

• identifying what - focal vision (fovea)

• determining where - ambient vision

he studied the what vs where pathways

who did schneider present his research along side and what did they study

• Held (cats)

• Ingle (fish)

• Trevarthen (monkeys)

what term did Travarthen coin

focal vision

what happened in the Travarthen study

the baby monkey had her vision lesioned and acted blind for 2 years but then started to catch bugs and they realized she still have vision in her periphery

what is the location difference between focal vision and ambient vision

• the focal system is mainly the central retina, macular region, fovea

• ambient vision is more in the periphery

what is the difference in awareness between focal vision and ambient vision

• focal vision requires this

• ambient vision does require it, it has a low cognitive load

to have comprehension what do you need

awareness

what is the difference in luminance between focal vision and ambient vision

• focal vision requires it (you cant read in the dark)

• ambient vision doesn’t require it (you could get to your car in the dark)

what is the difference in refractive error between focal vision and ambient vision

• focal vision is damaged or degraded by it

• ambient vision is not impacted by it

  • ex: you could walk without your contacts

what is the difference in optical rearrangement between focal vision and ambient vision

• focal vision has color fringes around the edges that never go away

• ambient vision can adapt to this

what is the difference in spatial frequency between focal vision and ambient vision

• focal vision uses higher frequency

• ambient vision uses lower frequency

what is needed for driving and why, give an example

focal and ambient vision

• identifying signs, hazards, and determining where you are on the road and where other drivers are

• ex: spacing out while driving or looking at a text but you stay on the road, even if you dont remember you didnt run off the road

  • out ambient system doesnt require much awareness (keep your car on the road and know when to stop)

how does night driving selectively degrade the focal system

• the ambient system is not impacted

• the focal system is impacted

do we tend to drive faster or slower at night

we speed up despite our decrease in vision

what happens to the amount of illumination from a given source as you move away from the source

it decreases

will you see the pedestrian first if you are driving at night or will they see your headlights first

the pedestrian will see your headlights first

how does illumination decrease

by the inverse square law

• I = c/d²

  • I = illuminance in foot candles

  • c = source output in candles

  • d = distance from source in feet

• there has to be some distance where the light is visible but not useful

after sunset how many twilights are there

3

what are the 3 twilights

• civil

• nautical

• astronomical

when does civil twilight occur

critical part of the transition from daylight to darkness

• 30 min after sunset or 30 min before sunrise

• this is when the sunset is about 6 degrees below the horizon

what does civil twilight correspond to

a certain amount of light available for us to use

• with illumination levels of 330 lux down to the dark limit of 3.3 lux

what does it mean to have a dark limit of 3.3 lux

focal vision is pretty useless by the dark limit of civil twilight

when does nautical twilight occur

the second half hour after sunset

• the sun is 6 - 12 degrees below the horizon

when does astronomical twilight occur

the third half hour after sunset

• the sun is 12 - 18 degrees below the horizon

explain the graph of selective degradation

• vection, visual acuity, and contrast sensitivity all work fine during the day

• vection does not drop off at all with the change in light

what is vection

the illusory movement

• you think you are moving but you are not

• it is part of ambient vision

what is visual acuity

how small of a size you can see

• focal vision

what is contrast sensitivity

our ability to see edges/contrast

• focal vision

when does our visual acuity get bad

30 min after sunset

• CIVIL TWILIGHT

what does squinting do and why is it an issue

eliminates the edges of the lens

• the edges are prismatic

what is a better alternative to squinting

looking through a pin prick through paper

what depends on the position of the sun

how well our visual systems perform

• focal vision is not good in the dark

• ambient system is fine in the dark

in what order is everything done in the nighttime until sunrise

everything is done in reverse

what is civil twilight distance

the distance in front of the vehicle where dark limit of civil twilight is reached (3.3 lux) and focal vision can be considered useful (not for detection)

• the lumination from headlamps is the same as the light outside

what were the details of andre and owens car study

• closed airforce base

• surveying equipment

• new cars

• coyotes

describe the traffic lane on the runway

• 2 way road

  • 12 ft wide

  • dots every 10ft for 800ft

  • travel lane and oncoming lane

how far can you see in front of you with lowbeam headlights

230ft

• could be shorter distances for oncoming traffic because of headlight positioning

how are headlights positioned on a car

down and to the right

in which direction would you be able to identify moving hazards from the best

horizontally moving objects coming from the right compared to coming from the left

where do you get maximum visibility from headlights

ground level

what happens to the max distance you can see in front of you with low beam headlights when you are at eye height

the distance gets closer

• it moves to 60ft

if you are driving at 70 miles down the road in optimal conditions, what is your stopping distance

400ft

• 1.9 seconds

what do high beam headlights do

• provide more light

• fill in light from above

• allow you to see a further distance

how far can you see at ground level with high beam lights

575 feet

how far can you see at eye height with high beam lights

500ft

how would you describe human factors

how we interact with our environment and our technologies

what are the goals of human factors

• increase efficiency

• productivity

• safety

• comfort

• all while decreasing user errors and accidents

give examples of human factors

• pencil grips

• screen displays in a car

• buttons on a steering wheel

• cockpit design on an USAF plane

• training and selection of workers

• human computer interactions

when did human factors start to “become a thing”

WWII with JJ Gibson

• studied pilots flying at night

what makes up human factors

• psychology

  • bio, personality, social, experimental, all psych

• physiology

• engineering

what is basic research

research that is done to increase general knowledge

• just investigating

• ex: can your dog see colors, what does drinking alcohol do to vision

what is applied research

research done to answer a specific question

• ex: why do air traffic controllers have more visual fatigue than office workers

what were H W Leibowitz’s thoughts about basic and applied research

he never saw the division between the two

• you use basic research to help solve applied research and use applied research to guide basic research

• they have a symbiotic relationship

what is visual acuity in contrast sensitivity and give an example

• its all based on size

• example: eye chart at the doctors

  • commonly used because its easy to use

what are the problems with traditional visual acuity measures

• usually stationary

• done in high luminance

• done in high contrast

• assessing vision for detail (NOT A SIZE THING)

• testing only high spatial frequencies

• retina extends 90 degrees to each side of fixation but 20 degrees from fovea is 20/200

what so you need to see an object

• light

• contrast

what is contrast

the difference between amount of light reflected from object and amount of light reflected from an objects surround

• its our ability to see edges, contours, borders, and changes in illuminance

what is the most important concept in visual perception

contrast

how do we measure contrast

sine wave gratings

what does the amplitude of the sine wave represent

the contrast

what is a sine wave grating

a visual stimulus with alternating darker and lighter areas with a sinusoidal luminance profile

• if you were to do this with a wave you would get a smooth increase and decrease

• if you were to do this with eye chart letters you would get a step function (aka square wave - harsh lines)

• looks like fuzzy stripes

what is a sine wave grating based on

spatial position

what are the units of the sine wave gratings

cycle per degree of visual angle

• any object in the world has a degree

what do higher spatial frequencies mean

• thinner stripes

• higher detail

• ex: seeing if someone shaved their beard or not

why do we use sine wave gratings for contrast sensitivity

they are simpler than square waves

• you can use fourier analysis on them

what is fourier analysis

breaking down a wave

• finding the equation

if you have a low spatial frequency what will the amount of stripes be like

less/low amount of stripes and thicker

if you have a high spatial frequency what will the amount of stripes be like

more stripes and thinner

how can a square wave be broken down

into a sine wave

can you test fine detail and coarse/global shapes and outlines

yes

• they have different spatial frequencies