9.2 - Human Performance and Limitations Flashcards
What is the anatomy of the eye
1: Cornea
2: Iris and Pupil
3: Lens
4: Retina
5: Fovea
What is the Cornea
The clear window at the front of the eye which allows light enter.
How much of the focusing ability is the cornea responsible for?
70 - 80%
What is the Iris and Pupil
The Iris (coloured part of the eye) controls the amount of light by varying the size of the pupil (the dark centre)
What factor can the Iris adjusted by
5:1
How does the lens focus
Ciliary muscles in the lens change their shape to adjust the level of focus. This is called accommodation
What does the Retina contain
Rods and Cones
How do the cones function
They function in good light, can detect fine detail and are colour sensitive, allowing the eye to distinguish about 1000 shades of colour
How do the Rods function
Rods cannot detect colour and are poor at distinguishing fine detail but good at detecting movement
How does the eye prevent an image falling into the blind spot
Constant rapid eye movement (saccades)
What is the Fovea
A small depression at the centre of the retina that is responsible for Central vision
How many nerve cells leading from the retina to the visual cortex
1.2 million
How many nerve cells in the inner ear
50’000
How many times more sensitive is the eye than the nose
24 times more sensitive is
How is Hypermetropia (long sightedness) caused
By a shorter than normal eyeball
Where is the image formed in an aye with Hypermetropia
Behind the retina
How is Myopia caused
By a longer than normal eyeball
Where is the image formed in an eye with Myopia
In front of the retina
What is Presbyopia
Loss of lens flexibility with age
What is Glaucoma
Build up in pressure of the fluid in the eye
What are cataracts
Clouding of the lens
What is Astigmatism
A misshapen cornea
What can excessive light cause
Increased Glare, especially for older people
What is Colour Vision Deficiency
Colour Blindness
What is the most common type of colour blindness
Red and green
What document controls the standards for vision
Regulation CAP 562 Leaflet H60
What are the functions of the ear
1: Detecting sounds
2: monitoring balance and acceleration
What are the 3 divisions of the ear
1: Outer ear
2: Middle ear
3: Inner ear
What does the outer ear do
Directs sound down the auditory canal to the ear drum
How long does the acoustic or aural reflex reduce noise levels
About 15 mins
How is air in the middle ear refreshed
By the eustachian tube
How are vibrations transmitted from the ear drum
The Ossicles
What is the Ossicles made up of
1: Hammer
2: Anvil
3: Stirrup
When must employers provided hearing protection and hearing protection zones
When normal speech cannot be heard clearly at 1 meter
When must employers assess the risk to workers health and provide training due to noise levels
If ambient noise is above where normal speech cannot be heard at 2 meters
What happens if the a noise exposure limit value that must never be exceeded is reached
Work must cease until a solution is provided
What is noise dose
A term that describes a combination of a noise’s duration and intensity
What is Time Weighted Average
Exposure to any sound over 80dB and measured over 8 hours as an average
What TWA noise level is considered hazardous and potentially damaging to the inner ear
Noise above 85dB for 8 hours
What level does ear plugs attenuate noise
Upto 20dB
What level does ear defenders attenuate noise
Upto 40dB
What is the naturally deteriorating of the hearing that can start from age 30
Presbycusis
Information processing is the process of what
1: Receiving information through the senses
2: Analysing information
3: Deriving meaning from information
4: Storing information
What are the memory stores known as
1: Iconic Memory
2: Echoic Memory
What does Iconic Memory do
Provides a smooth stream of visual information to the brain which can be extracted over an extended period in the visual short term memory
What does Echoic Memory do
Registers sound
How long is visual information stored in the Iconic memory
Upto half a second
How long are sounds stored in the Echoic memory
Upto two seconds
What are the forms of attention
1: Selective
2: Divided
3: Focussed
4: Sustained
What is selective Attention
When a person is monitoring several sources of input but focuses on the source that seem more important
What is divided attention
When a person is required to do more than one thing at the same time
What is focussed attention
When a person’s attention is channeled towards a single source and avoiding distractions
What is Sustained Attention
The ability to maintain concentration and remain already over long periods of time
How is attention influenced
By arousal level and stress
What is the definition of perception
The process of assembling sensations into a useable mental representation of the world
What are the processes of memory
1: Encoding
2: Storage
3: Retrieval
What is the process of getting information into outlet brains
Encoding
How is the encoded information put into storage in the brain
Three stages
1: Sensory memory
2: Short term memory or working memory
3: Long term memory
How long does sensory memory hold information
Upto a couple of seconds. Know as ultra short term memory stores
How much information can the short term memory hold and for how long
5-9 items for 10-20 seconds
How long can long term memory hold information
It’s continuous storage of information and has no limits
What are the types of long term memory
1: Semantic Memory
2: Episodic Memory
What is Semantic memory
It’s the store of general, factual knowledge
What is Episodic memory
The memory of specific events such as past experiences, people, events and objects
What is the memory process
1: Encoding
2: Storage
2: Retrieval
4: Decision
What is Situation awareness
The synthesis of an accurate and Upto date mental model of one’s environment and state
What is the fear of enclosed spaces
Claustrophobia
What is the fear of heights
Acrophobia
What is a motor programme
A organised series of movements, made up of subroutines that are run together in order to
What is neuroplasticity
The continual changes that take place in the brain as you experience and adapt to your surroundings
