mod 9.2human perfomance and limitations

what is the job of the cornea

acts as a fixed focusing device

how is focusing achieved by the cornea

bending the shape of the cornea onto incoming light rays

how much of the focusing ability is the cornea responsible for

70-80%

what is the job of the iris and the pupil

the iris is the coloured part of the eyes and controls how much light enters the eyes my varying the size of the pupil

what is the job of the lens

after the image is passed through the pupil it changes the shape by cilary muscles for the final focusing on the retina

when the lens of the eyes change shape to focus this is known as what

accomodation

in order for the lens to focus near or far in what way does the lens change shape

to focus near the lens is thickens to focus far it flattens

the degree of accommodation can be affected by what factors

old age and fatigue

when a person is tired there vision is less sharp this is known as

visual acuity

were is the retina located, what is it connected to and what are the two types of cells found around there

1.located on rear wall of the eyeball

2.connected to optical nerve

3.two type of cells rods and cones

whats do the rods and cones do

they detect light

rods- black and white, no detail good at perifpheal vision

cones- colour, fine detail colour sensitive

what occurs at the point that the optic nerve enters the retina between the rods and cones

a blindspot occurs

how to avoid getting caught out by blind sport

by rapidly loving the eye around the area of interest (saccades)

what is the fovea

the central area of the retina were cones are concentrated and visual image is focused

is there more rods or cones the fovea

in the centre theres only cones and then more rods as it goes into the prefiphery

when is blindspot not evident

when viewing with both eyes

how sessitive is the eye compared to the ear

24 more times

were is the brain inverted and flipped

inverted in the optic nerve and flipped in the brain

what is visual acuity

the ability for the eye to discriminate sharp detail at varying distances

what 5 factors can affect visual acuity

imperfections on the eye, age, foreign substances, environmental factors and how it is viewed

when does blindspot occur

at the point where the optic nerve enters the retina between rods and cones

what is long sightedness known as

hypermetropia

what lens overcomes long sightedness (hypermetropia)

convex lens

what is shortsightedness known as

myopia

how can shortsightedness corrected

concave lens

were is the image formed in longsighted and what cant you see

the image is behind the retina and blurry when looking at close objects

were is the image formed when shortsighted and what cant you see

the image is infront of the retina and distant objects are blurred

what is presbyopia and what causes it

the lens becomes less flexible (looses elasticity) as the person grows older

how an foreign substances affect your vision and what is it called

carbon monoxide in the blood means less oxygen in the eyes and its known as hypoxia

how long for the rods and cones to adapt to the dark

7mins for the cones and 30mins for the rods

what is visual acuity

the ablity for the eyes to discriminate sharp detail ad varying distances

what is the value of normal acuity

20/20 (feet)

6/6 meters

when we use info from objects to distinguish what we are seeing, what is this called

visual cues

what 4 things is colour vision important for

1 recognising components

2 distinguishing between wires

3 using various diagnostic tools

4 lights on the airfield

how many men and women does colourblindness affect

8%men 0.5% women

what can help when looking in low light or colour loss

by looking at it offset to make use of the rods in the peripheral

what lens fixes presbyopia

convex

what is the 3 divisons of the ear

outer middle inner

what are the two functions of the ear

1 balance and sensing acceleration

2 detect sound

what is the job off the outer ear

to direct sound down the auditory canal

what are the 3 bones in the middle ear called

ossicles

what is name of the two muscles that that help protect at 80db

acoustic or aural relex

what tube refeshes the middle ear and balances the eardrum

estachian tube

what is the inner filled with

fluid

the last of the ossicles is connected to what

cochlea

what membrane is in there, what is it covered by

1 basilar membrane

2 covered by hair like cells

when the hair like cells in the cochela vibrate what happens

vibrations cause neural impulses that are transmited to the brain by the auditory nerve

how is amplitude and frequency measured

db - loudness/volume

hz - tone/pitch

at what db should protection be worn

85db

what is NIHL and how long does it last

noise induced hearing loss and can be a few seconds to permeant

what is conductive deafness

damage to the conductive system

what happens at 90db

empployer should do all that they can to reduce noise

at 140db what happens

noise pain and avoid

what is noise dose and how is it measured

combination of intensity and duration

measured in TWA time weighted average

what are the two types of hairs in the cochlea and what do they detect

long - low frequency

short - high frequency

what is it called when you grow older and your hearing deteriorates

presbycusis

who is responsible for using protection

the individual

were is physical stimuli received by and stored for how long

received by sensory receptors and stored briefly in sensory stores

were is visual info stored and for how long

iconic memory for up to 0.5sec

were are sounds stored and for how long

echoic memory up to 2 seconds

what are the 4 types attention an describe them

selective, monitoring several inputs “cocktail party”

divided, required when doing more than one thing

focused, singe source and avoiding distractions

sustained, maintaining alert on one task over a period of time

what is perception

what you think vs what is actual

whats meaningful and whats not

transforming data into information

what is decision making

generation of alternative courses of action based on available information knowledge experience expectation ect and selecting the preferred option

what is the 3 forms of memory

ultra short term (sensory storage)

how long does your short term memory last for

10-20 seconds

how can your short term be extended

rehearsal, chunking, encoding

what is the capacity of long term memory

unlimited

what can the long term memory be divided into and description

semantic memory - facts rules ect

episodic memory - events people objects

what can the shor term memory be divided into

echoic - hear

iconic - see

what is a motor programme

tasks that are performed often that become automatic with the skill in the long term memory

what is situation awareness

to be aware of whats going on around you good or bad

why is the human mind fallible

forgetting

what is claustrophobia

fear of being in a enclosed space

how much factor of Light can the eyes adjust

5:1