Human Abilities

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Human Abilities

• Understanding humansor at least some aspect of
  them!

2
Agenda

• Questions
• Project part 1
• Continuing task analysis
• Sensing / input capabilities
• Memory / storage capabilities

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Project part 1

• Presentations on Monday
• All team members should be there
• If absent, -5 deductive credit on project part 1
• 1 or 2 person(s) talk
• 1 or 2 slides
• What was the domain?
• Who are the target users?
• The problem
• Current approaches issues
• Techniques for investigating 2-4

4
Project part 1

• Order of presentation on the Swiki
• You have
• 5 minutes to talk
• 2-3 minutes for questions
• Point is class discussion on what you are
  investigating come, give feedback to others

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Basic human capabilities

• Change much more slowly than technology
• Have limits, which are important to understand

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Processing model

• DFAB
• Sense / input descriptions
• Storage / memory models

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Humans as I / O machines

• Senses
• Vision
• Hearing
• Touch
• Smell / Taste
• Feed sensory memory

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Visual perception

• Size depth
• Visual angle
• Visual acuity fine detail
• Law of size constancy
• Cues size, height, familiarity
• Brightness
• Luminance amount of light emitted by an object
• Flicker
• Contrast function of luminance of object
  background
• Color
• Hue, intensity (brightness), saturation
• Number of colors an individual (without training)
  can identify is in region of 10.
• Color blindness 8 males, 1 females suffer

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Human perception capabilities limitations

• Split a picture into a collection of small dots
  and we can reconstruct it
• Pixels resolution
• Present consecutive frames of a dynamic scene
  and we can smooth it
• gt15 fps refresh rate
• Optical illusions
• Ambiguity context
• Expectations compensation

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Read this

• The quick brown
• fox jumps over the
• the lazy dog.

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Hearing

• Pitch frequency of sound
• Loudness amplitude
• Human ear can hear frequencies between 20Hz to
  15kHz
• Distinguish frequency changes less than 1.5Hz
• Cocktail party effect
• Selective hearing
• Filtering of background noise

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Touch / motor

• Pressure
• Intense pressure (heat / pain)
• Temperature (hot / cold)
• Sensitivity
• Kinesthesis awareness of position of body
  limbs

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Smell / taste

• Largely unexplored with respect to computing

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Smell
Joseph Kaye, Making scents aromatic output for
HCI ACM Interactions Volume 10, Number 1 (2004),
Pages 48-61
Solenoid-controlled scent bottles
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Memory

• 3 kinds
• Distinguished by
• Main code type
• Storage capacity
• Decay time of an item

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Sensory / perceptual memory

• Physically encoded
• Impacted by physical characteristics of signal
• Low capacity
• Rapid decay (msec)

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Short-term or working memory

• Symbolic, nonphysical acoustic or visual coding
• 7 plus / minus 2 chunks
• Rapid access in the order of 70 ms
• Decay in the order of 200 ms

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What is a chunk

• A meaningful grouping of information
• 4 7 9 3 6 1 9 0 4 9
• vs.
• 404 894 7512
• Very user task dependent
• My chunk may not be your chunk!

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Long-term memory

• Two types
• Episodic - events experiences in serial form
• Semantic - structured record of facts, concepts
  skills
• Capacity (limitless?)
• No decay!
• Catch retrieval depends on network of
  associations

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Principles for retrieval

• How information is perceived, understood and
  encoded determines likelihood of retrieval
• Recall vs. recognition

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Memory Characteristics

• Things move from STM to LTM by rehearsal
  practice and by use in context
• Do we ever lose memory? Or just lose the link?
• What are effects of lack of use?
• We forget things due to decay and interference
• Similar gets in the way

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Processing

• Recognize-act cycle
• Contents of WM trigger actions held in LTM
• Speed of processing increases with attention
  practice

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Problem Solving

• Storage in LTM, then application
• Reasoning
• Deductive -
• Inductive -
• Abductive -
• Goal in UI design - facilitate problem solving!
• How?? Take time to think about this right now!

If A, then B
Generalizing from previouscases to learn about
new ones
Reasons from a fact to theaction or state that
caused it
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Thinking, reasoning problem solving

• Newell Simons theory
• Problem spaces
• Employs heuristics
• Means-end analysis
• Foundational to HCI modeling

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Things weve left out?

• Emotion
• Individual differences

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Why did we learn this?

• Model of the user
• Predicting interactions results