Humans

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Humans
CS/PSYC 4750 Spring, 2001
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Understanding humans

• Humans evolve much more slowly than technology
• There are limits to human capabilities
• We cant see in UV
• ......the I/O processor assumption
• All humans are fundamentally the same (differ
  only in parameters)

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Understanding Humans

• (1) Humans interpreters/predictors
• cog. psych. AI 4750 Part 1
• (2) Humans sensory processors
• sensory psych., EE CS systems
• (3) Humans actors in environment
• Activity Th., ethnog., ecol. psych.
• Fundamental question How much how rapidly do
  humans change?

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Humans as I/O machines

• Senses
• vision
• hearing
• touch
• smell/taste
• proprioception
• kinesthesia

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Vision

• Two stages in vision
• - physical reception of stimulus
• - processing and interpretation of stimulus
• The physical apparatus the eye
• - mechanism for receiving light and transforming
  it into electrical energy
• - light reflects from objects their images are
  focused upside-down on retina
• - retina contains rods for low light vision and
  cones for colour vision
• -ganglion cells detect pattern and movement

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Depth and Size Perception

• visual angle indicates how much of field of view
  object occupies
• visual acuity is ability to perceive fine detail
• familiar objects perceived as constant size
  despite changes in visual angle (law of size
  constancy)
• cues like overlapping help perception of size and
  depth

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Brightness

• Brightness subjective reaction to levels of
  light
• affected by luminance of object
• measured by just noticeable difference
• visual acuity increases with luminance

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Color Perception

• Color made up of hue, intensity, saturation
• Cones sensitive to color wavelengths
• Blue acuity is lowest
• 8 males and 1 females color blind (esp.
  Red/Green confusion)

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Graphical Representation at the Interface

• Graphical modeling and 3-D
• Graphical coding
• Graphical coding for quantitative data
• Color coding
• Color versus monochrome coding
• Icons

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Compensation Illusions

• Human vision compensates for movement and changes
  in luminance.
• Context is used to resolve ambiguity.
• Overcompensation sometimes causes optical
  illusions

Ponzo
Muller/Lyer
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Reading

• Stage model of reading
• (1) visual pattern perceived
• (2) decoded using internal language
  representation
• (3) interpreted using knowledge of syntax,
  semantics, pragmatics

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Perception in reading

• Reading involves saccades and fixations.
• Perception occurs only during fixations.
• Word shape is important to recognition.
• Negative contrast improves reading from computer
  screen.

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Hearing

• Provides information about environment
  distances, directions, objects etc.
• People can hear from 20Hz to 15kHz (less accurate
  distinguishing high frequencies).
• Auditory system filters sounds can attend to
  sounds over background noise ( cocktail party
  phenomenon).

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Touch

• May be key sense for visually impaired.
• Receptors in the skin
• - thermoreceptors (heat and cold
• - nociceptors (pain)
• - mechanoreceptors (pressure)
• Some areas more sensitive than others (e.g.
  fingers).

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6th, 7th and 8th senses

• Proprioception
• awareness of body position through
• affects comfort and performance
• Kinesthesia (kin(a)esthesis)
• awareness of body movement
• Balance (vestibular organ of inner ear)
• awareness of body orientation w.r.t. vertical

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Movement perception

• Tight integration of (i) perception motor
  planning, (ii) movememnt execution and (iii)
  proprioceptive, kinesthetic, vestibular and
  visual feedback
• Response reaction movement
• (1) Movement depends on age, fitness etc.
• (2) Reaction depends on modality
• (visual 200ms auditory 150 ms pain 700ms)

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Fitts Law

• Time taken to hit a visual target using hand/eye
  coordination
• Mt a b log2(D/S 1)
• (a and b are empirical constants,
• D is Distance S is Size)
• Targets in general should be large as possible
  and the distances as small as possible.

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Box Model of Memory
Sensory memories (iconic) (echoic) (haptic)
Short-term/ working memory
Long-term memory (semantic) (episodic)
Sensory buffers Constantly overwritten
Recency effect recall of recent items
best. Evidence for several working memories, but
auditory coding is most common, so auditory
confusions most likely
Selective attention (governed by arousal)
Scratch-pad for temporary recall rapid access
(70ms) rapid decay (200ms) limited capacity
(7
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Focusing Attention

• Focused and divided attention
• Focusing attention at the interface
• Structuring information
• Other techniques for guiding attention
• Multitasking and interruptions
• Automatic processing

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LTM the 3rd box
Long-term memory
Sensory memories (iconic) (echoic) (haptic)
Short-term/ working memory
Semantic
Episodic
Repository for all our knowledge slow access
(0.1s) slow decay (if any) effectively
unlimited capacity
Facts, concepts, skills
Events
Semantic memory structure provides access to
information represents relationships between
information supports inference associative
recall based on meaning hence, meaning-related
confusions
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Consolidation

• Information moves from STM to LTM by rehearsal
• retention ? rehearsal time
• distribution of practice effect
• structure, meaning and familiarity make
  information easier to remember

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Forgetting

• Decay
• Information lost gradually but slowly
• Interference
• New information replaces old (retroactive)
• Old may interfere with new (proactive)
• Inhibition
• Can choose to forget

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Retrieval

• Recall
• Information reproduced from memory
• Can be assisted by cues, (e.g. categories,
  imagery)
• Recognition
• Information gives knowledge that it has been
  seen before
• Information is the cue

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Knowledge representation

• Declarative knowledge knowing that
• Semantic networks
• Frames
• Scripts
• Procedural knowledge knowing how
• Scripts
• Production rules

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Semantic networks
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Frame-based model of semantic memory

• Knowledge is organized in data structure
• Slots in structure are instantiated with
  particular values for a given instance of data
• ...translation for CS people
• frames ??classes in the head
• slots ? variables/methods in the head)

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General knowledge as frames
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Script-based memory

• Scripts frames for stereotypical processes
  (e.g. eating in a restaurant)
• used for interpreting situations
• generalize episodic-memory events

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Production rules

• Representation of procedural knowledge
• Condition/action rules
• if condition is matched, rule fires

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Slips and Mistakes

• Slips error in execution of correct intention
• E.g. Capture errors
• (...ate - ...ation)
• Errors of attention
• Mistakes error in selection of goal or method
  for accomplishing it
• Errors of knowledge