HCI

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HCI

• Model Human Processor
• Memory

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Model Human Processor Basics

• Based on Empirical Data
• Three interacting subsystems
• Perceptual (eg. read-scan)
• Cognitive (eg. think)
• Motor (eg. respond)

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Information Processing

• Usually serial action
• Respond to buzzer by pressing button
• Usually parallel recognition
• Driving, reading signs, listening to radio

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Model Human Processor Basics

• Parameters
• Processors cycle time of 50-200ms
• Memories have type, capacity, decay time
• Types
• Visual
• Auditory
• Tactile
• Taste, smell, proprioception, etc

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Model picture
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Model Picture Closeup
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Perceptual Processor

• Continuously grabs data from the sensory system
• Cycle time 100ms 50 - 200 ms
• Passes data to Image Store in unrecognized form
• Array of Pixels (or whatever it is) from eyes
• Sound Intensities from ears

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Sensory Store

• The input buffer of the senses
• Stores most recent input unrecognized
• Storage time and capacity varies by type
• Visual Nominal Range
• Capacity 17text letters 7 - 17 letters
• Decay Time 200ms 70 - 1000 ms
• Audio
• Capacity 5 text letters 4.4-6.6 letters
• Decay Time 1500 ms 900 - 3500 ms

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Perception

• Stimuli that occur within one PP cycle fuse into
  a single concept
• movies (frame rate)
• Frame rate gt 1 / Tp 1/(100 msec/frame) 10
  f/sec
• morse code listening rate
• Perceptual causality
• two distinct stimuli can fuse if the first event
  appears to cause the other
• events must occur in the same cycle

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Memory

• Two types
• Short-term memory
  Conscious thought, calculations
• Long-term
  Permanent, remember everything ever happened to
  us

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Memory Sort Term

• Short Term (Working) Memory (WM)
• Gets basic recognition from Sensory Store
• Stop sign vs. red octagon w/white marks
• 7 /- 2 chunks
• 4048946328 vs. 404-894-6328
• WM Nominal Range
• Capacity 7 chunks 5 - 9 chunks
• Decay Time 7 seconds 5 - 226 seconds
• Access Time 70ms 25 - 170 ms

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Memory Long Term

• Long Term Memory (LTM)
• Unlimited size
• Slower access time (100ms)
• Little decay
• Episodic Semantic
• Why learn about memory?
• Know whats behind many HCI techniques
• Predict what users will understand

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LT Memory Structure

• Episodic memory
• Events experiences in serial form
• Semantic memory
• Structured record of facts, concepts skills

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MHP Operation

• Recognize-Act Cycle
• On each cycle, contents in WM initiate actions
  associatively linked to them in LTM
• Actions modify contents of WM
• Discrimination Principle
• Retrieval is determined by candidates that exist
  in memory relative to retrieval cues
• Interference by strongly activated chunks

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Memory Characteristics

• Things move from STM to LTM by rehearsal
  practice and by use in context
• We forget things due to decay and interference

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Interference

• Interference
• Two strong cues in working memory
• Link to different chunks in long term memory

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Interference

• Exercise Read the colors of these words
• Introduction
• Background
• Theory
• Lemma
• Proof

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• Read the colors of the words
• Black
• Red
• Orange
• Yellow
• Blue