[HCI] 2. Human 1

the human

• Information I/O …
  • visual, auditory, haptic, movement
• Information stored in memory
  • sensory, short-term, long-term
• Information processed and applied
  • reasoning, problem solving, skill, error
• Emotion influences human capabilities
• Each person is different

Vision

• Two stages in vision
  • Physical reception of stimulus (입력을 받아들이는 감각)
    • Eyes
    • Ears
    • Fingers
  • Processing and interpretation of stimulus (카메라로 사진을 찍고 나서의 처리과정과 같은 과정)
    • Perception
    • Memory

The Eye - physical reception

• Mechanism for receiving light and transforming it into electrical energy
• Light reflects from objects
• Images are focused upside-down on retina
• Retina contains rods(모든 종류의 파장이 가능해서 강조를 파악) for low light vision and cones(특정 주파수를 통해 wavelength에 의해서 가능한 cell) for colour vision
• Ganglion cells (brain!) detect pattern and movement

Interpreting the signal

• Size and depth
  • Visual angle indicates how much of view object occupies (relates to size and distance from eye)
  • Visual acuity is ability to perceive detail (limited)
  • Familiar objects perceived as constant size (in spite of changes in visual angle when far away)
    • 책상을 예로 우리의 시각에서는 사다리꼴처럼 보이지만 뇌에서는 이를 직사각형으로 인식하거나 아무리 멀리 있어도 그 크기를 가늠할 수 있는 것이다.
  • Cues like overlapping help perception of size and depth

Interpreting the signal (cont)

• Brightness
  • Subjective reaction to levels of light
  • Affected by luminance of object
  • Measured by just noticeable difference
  • Visual acuity increases with luminance as does flicker(깜빡깜빡)
• Color
  • Made up of hue, intensity, saturation
  • Cones sensitive to colour wavelengths
  • Blue acuity is lowest (파란색의 명암이 구분이 제일 힘듬; 그린 > 레드 > 블루)
    • acuity: 명확히 보고 듣고 생각하는 능력
  • 8% males and 1% females colour blind
• The visual system compensates for:
  • Movement
  • Changes in luminance.
• Context is used to resolve ambiguity
• Optical illusions(왜곡) sometimes occur due to overcompensation

Optical Illusions

Reading

• Several stages:
  • Visual pattern perceived
  • Decoded using internal representation of language
  • Interpreted using knowledge of syntax(문법), semantics(의미), pragmatics(맥락)
• Reading involves saccades(홱 스킵하면서 읽는) and fixations(가만히 있는)
• Perception occurs during fixations
• Word shape is important to recognition
• Negative contrast improves reading from computer screen

Hearing

• Provides information about environment: distances, directions, objects etc.
• Physical apparatus:
  • Outer ear: protects inner and amplifies sound
  • Middle ear: transmits sound waves as vibrations to inner ear
  • Inner ear: chemical transmitters are released and cause impulses in auditory nerve
• Sound
  • Pitch: sound frequency (높낮이)
  • Loudness: amplitude (크기)
  • Timbre: type or quality (음색)

• Humans can hear frequencies from 20Hz to 15kHz
  • Less accurate distinguishing high frequencies than low.
• Auditory system filters sounds
  • Can attend to sounds over background noise.
  • For example, the cocktail party phenomenon(웅성웅성하고 시끄러운 상황에서 대화를 하고 있는 상대의 말소리만 catch하는 능력).

Touch

• Provides important feedback about environment.
• May be key sense for someone who is visually impaired.
• Stimulus received via receptors in the skin:
  • Thermoreceptors: heat and cold
  • Nociceptors: pain
  • Mechanoreceptors: pressure (some instant, some continuous)
• Some areas more sensitive than others e.g. fingers.
• Kinesthesis - awareness of body position
  • 눈을 감고도 내가 어떤 자세를 취하고 있는지를 인식하고 있는 것.
• Affects comfort and performance.

Movement

• Time taken to respond to stimulus:
  • reaction time + movement time
• Movement time dependent on age, fitness etc.
• Reaction time - dependent on stimulus type:
  • visual ~ 200ms
  • auditory ~ 150 ms
  • pain ~ 700ms
• Increasing reaction time decreases accuracy in the unskilled operator but not in the skilled operator.

Movement (cont)

• Fitts’ Law describes the time taken to hit a screen target
  • Shannon formulation (Dr. Scott MacKenzie)

• where:
  • a and b are empirically determined constants
  • Mt is movement time
  • D is Distance
  • W is Width of target

targets as large as possible distances as small as possible

Memory

• There are three types of memory function:

• Selection of stimuli governed by level of arousal.

Sensory Memory

• Buffers for stimuli received through senses
  • Iconic memory: visual stimuli
  • Echoic memory: aural stimuli
  • Haptic memory: tactile stimuli
• Examples
  • Sparkler trail
  • Someone else’s name called in public
• Continuously overwritten

Short-term Memory (STM)

• Scratch-pad for temporary recall
  • Rapid access ~ 70ms
  • Rapid decay ~ 20s to 30s
  • Limited capacity – 7 ± 2 chunks

Examples

212348278493202

0121 414 2626

HEC ATR ANU PTH ETR EET

Long-term Memory (LTM)

• Repository for all our knowledge
  • Slow access ~ 1 to 10 seconds
  • Slow decay, if any (사라지지 않을지도 모름)
    • 연구 중에는 실제로 사라지지 않지만 해당 기억과 연결하는 시냅스가 끊어져서 기억이 안 나는 것일 수도 있다.
  • Huge or unlimited capacity
• Two types
  • Explicit memories are declarative memories, include all of the memories that are available in consciousness
    • Episodic memory & Semantic memory
  • Implicit memories are those that are mostly unconscious
    • Procedural memory & Emotional memory
    • 의식적으로 기억하지 않는, 글씨 쓸 때 펜을 어떻게 잡고 있고 어떻게 쓰고 있는지 생각 안 하는 것처럼

Long-term Memory (cont.)

• Explicit memories
  • Episodic: serial memory of events (일어났던 사건을 기억하는)
  • Semantic: structured memory of facts, concepts, skills (역할을 기억하는)
  • Semantic LTM derived from episodic LTM
• Implicit memories
  • Procedural: the use of objects or movements of the body, such as how exactly to use a pencil or ride a bicycle
  • Emotional: the memory for events that evoke a particularly strong emotion
• Semantic memory structure
  • Provides access to information
  • Represents relationships between bits of information
  • Supports inference
• Model: Semantic Network
  • Inheritance – child nodes inherit properties of parent nodes
  • Explicit relationships between bits of information
  • Supports inference through inheritance

LTM - Semantic Network

Models of LTM - Frames

• Information organized in data structures
• Slots in structure instantiated with values for instance of data
• Type–subtype relationships

Models of LTM - Scripts

• Model of stereotypical information required to interpret situation
• Script has elements that can be instantiated with values for context
• 수의사를 만나러 가는 스크립트

Models of LTM - Production Rules

• Representation of procedural knowledge.
• Condition/action rules
  • if condition is matched
  • then use rule to determine action

LTM - Storage of information

• Rehearsal
  • Information moves from STM to LTM
• Total time hypothesis
  • Amount retained proportional to rehearsal time
• Distribution of practice effect
  • Optimized by spreading learning over time
• Structure, meaning and familiarity
  • Information easier to remember

LTM - Forgetting

• Decay
  • Information is lost gradually but very slowly
• Interference
  • New information replaces old: retroactive interference
  • Old may interfere with new: proactive inhibition
• So may not forget at all memory is selective …
• Affected by emotion
  • Can subconsciously ‘choose’ to forget

LTM - 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
  • Less complex than recall - information is cue*(recall과의 차이)

Types of Human Memory: by Luke Mastin