8. Human Sensory

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8. Human Sensory Information Processing System
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Human Vision

• Functional physiology of human vision

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Photometry

• Light is electromagnetic energy from 400-700 nm

700
(m)
(nm)
Red
Yellow
600
Green
500
Cyan
Blue
400
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Photometric Terms

• Radiance
• light energy at specific wavelengths
• Luminance
• total perceived energy emitted from surface
• Illuminance
• perceived energy falling on surface
• Chrominance
• color of light

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Human Hearing Sense

• Frequency dependent
• Always on
• Subject to temporary loss of sensitivity
• Subject to permanent, irrecoverable injury from
  noise over exposure

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Noise Exposure Effects

• Hearing loss temporary and permanent
• Performance decrements, esp. for cognitive tasks
• Increased perceived stress levels
• Hypertension, increased blood pressure

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HIP Model (Wickens, 1984)
Attentional Resources
Short Term Sensory Store
Perception
Decision Making
Response Execution
Working Memory
Long-Term Memory
Memory
Feedback
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Perception

• Detectionis a single/stimulus present
• Identificationnoting the characteristics of the
  signal stimuli
• Recognitiondetermine type of signal

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Signal Detection Theory

• Describes Perception when
• 2 states of a signal
• noise is present
• Signal Present Signal Absent
• Yes
• Hit False
• Operators Alarm
• Response
• NO Miss Correct Rejection

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Memory

• 3 primary activities
• encoding transformation
• Performing by working memory usually it is
• Spatial encoding (pictures)
• Verbal encoding (memory as sounds)
• storage holding2 primary areas (working and
  long term)
• retrieval -- locating and bringing to conscious
  awareness (increases in difficulty with age)

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Decision Making

• Evaluating Alternatives and selecting a course of
  action
• What influences DM? Differences, experiences,
  and biases
• Research findings help to describe the human
  decision making process
• emphasis on early information
• personal preferences will influence
• limited capacity for analyzing options

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Attention

• Attention is the allocation of cognitive
  resources to perception
• Selectivemay monitor several channels to perform
  a single task to determine if an event has
  occurred (e.g. pilot, driver, etc.)
• More channels to monitor decreases our
  performance
• If signals primarily in a few channels, we will
  direct our efforts to those channels
• Guidelines for Design of Tasks
• Use few channels
• Identify important channels for effective
  resource allocation
• Reduce stress
• Preview where signals will occur in the future
• Train on effective scanning patterns
• Place channels close together
• Make auditory channels distinctly different from
  background noise
• If responses are required, ensure there is ample
  time to respond

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Mental Workload

• No single measure can completely measure WL
• Valid measures are used for
• Allocating functions and tasks between operators
• Comparing equipment alterations with respect to
  WL
• Monitor operators to change task difficulty or
  function allocation
• Operator selection and assignment
• Primary Task Measures
• Major activities required of the operator
• Secondary Task Measures
• Spare resources are used to perform these tasks

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Mental Workload

• Physiological Measures
• Evoked brain potentials
• Pupillary response
• Respiration rate
• Body temperature
• Subjective Measures
• Questionnaires, surveys (most common NASA TLX,
  SWAT, Cooper Harper Scale)