Controlled Displays
- Created by: Sess
- Created on: 20-05-15 07:38
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- Controlled Displays
- Tracking
- Pursuit
- When the input and outputs are on separate displays or separate elements of display
- The operator attempts to follow the input with the output
- The operator can better keep track of the input and anticipate it
- If range is larger, display is zoomed out as they show the entire range of output at once
- Compensatory
- Input and output combined to show only the difference between the two.
- Reduces system error
- Can be used on big or small displays due to smaller scale range
- Methods used to investigate human tracking
- Human Limitations in Tracking
- We have a limited processing capacity
- We have a limited bandwidth (if there are 3 displays, how does one control them?)
- We have a limited ability to anticipate
- Influencers of Performance
- Preview
- If you get a preview, you can pick things up faster
- Lag
- Can occur at any order
- Results in confusion + frustration
- Error
- Can be minimized by training or lower order systems
- Pursuit or compensatory
- Pacing
- Everyone has differing pace so system needs to be adjustable
- Alternatives?
- Hick's Law states that reaction time increases with the number of alternatives (1951)
- Preview
- Pursuit
- Controls
- Orders of control
- 1) Zero Order
- The cursor controls the location of the target
- If you hold the cursor still, the system will be still
- More precise, more human efficient
- e.g. pen across paper, cursor on computer screen
- 2) First or Rate Order
- Velocity control (or rate of the change of position)
- Saves human effort
- If you hold a joystick in a certain direction, velocity increases
- 3) Second Order
- Rate of change of velocity
- Hard to control, rarely used
- Requires loads of effort and experience
- 4) Higher Order e.g. 3rd or 4th
- Response errors increase with increasing order of control
- Wickens (1986)
- 1) Zero Order
- Spatial
- Buttons should be grouped by functionality
- Knobs shouldn't be far from their corresponding display
- Movement
- Compatible movement to what they are supposed to do
- Human stereotypes need to be considered
- Orders of control
- Displays
- Visual
- Used for long, complex messages
- Used if the message will be refered to
- Or if it doesnt need to be immediately read
- Used if dealing with a certain location
- Or if auditory system is overburdened due to a noisy area
- Auditory
- For short and simple messages
- The message deals with events in time that cannot be delayed
- The location is too dark or bright for media
- Tactile/Haptic
- Proprioceptive
- Olfactory
- Visual
- Effects of Automation
- Advantages
- Freedom from tedious work
- Saves time + money
- Greater accuracy
- Greater productivity
- Disadvantages
- Greater unemployment
- De-socialisation
- Remoteness: a person is not hands on with their job
- De-skilling: you become out of practice
- Discomfort in assuming control
- Technical Illiteracy
- Abandonment of responsibility if it goes wrong
- Advantages
- Perceptual Principles
- Quantitative or qualitative displays
- eg. clock for quantitative or traffic light (red means stop) for qualitative
- Vision Apprehension Limits
- We can only see 5-6 things at once
- Factor in the visual angle of seeing things
- Coding or symbols?
- Similarity Principle
- Proximity Principle
- Wertheimer (1923)
- Symmetry Principle
- Common Fate Principle
- Continuity Principle
- Objects that are aligned tend to be grouped
- Bridger (1995)
- Closure Principle
- Pulling an complete form from partial information
- Prevents us seeing the blind spot
- Past Experience
- Quantitative or qualitative displays
- Tracking
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