imk02 prinsip usability

8/14/2019 IMK02 Prinsip Usability

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Interaksi Manusia dan Komputer

Prinsip Usability 1/17

Usabi l i t y Pr inc ip les

Human Ab i l i t y

Hum an Capabi l i t ies

Memory

Process

Observat ions

Problem Solv ing


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Usability Principles

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Hum an Ab i l i t ies

Good Infinite capacity LTM

LTM duration &

complexity High-learning

capability

Powerful attention

mechanism Powerful pattern

recognition

Bad

Limited capacity STM

Limited duration STM

Unreliable access toLTM

Error-prone processing

Slow processing


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Hum an Capabi l i t ies

Why do we care? (better design!)

Want to improve user performance

Knowing the user informs the design

Senses (Vision, Hearing, Touch) Information processing

Motor System

Time and effort expendedto complete tasks


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VISION

Visual SystemEye

Retina

Neural pathway

~ 80% of brains operation

SENSESVision, Hearing, Touch


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Sensitivity luminance: 10-6~107 mL (see notes)

Acuity

detection, alignment,recognition (visual angle)

retinal position: fovea has best acuity

Movement tracking, reading, vibrations

Note: Vision decreases with age Implications (??)

Font size & location depends on task

Much done by context & grouping

Visual Abil ities


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COLOR

Sensory response to electromagneticradiation in the spectrum betweenwavelengths 0.4 - 0.7 micrometers

0.5

visible

10-110-6 105 108

gamma ultraviolet microwave tv

Color & the retina

380 (blue) ~ 770nm (red)Problems with cones or ganglion cells causes problems with color

perception(Not really color blindness)

8% males, 0.5% femalesImplications: (??) - Avoid saturated colors

- Color coding should be redundant when possible


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Color Vis ion


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HEARING

Capabilities (best-case scenario) pitch - frequency (20 - 20,000 Hz)

loudness - amplitude (30 - 100dB)

location (5 source & stream separation)

timbre - type of sound (lots of instruments)

Often take for granted how good it is(disk whirring)

Implications (??)


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Three main sensations handledby different types of receptors:

Pressure (normal)Intense pressure(heat/pain)Temperature (hot/cold)

Sensitivity, Dexterity,Flexibility, Speed

Where important?Mouse, Other I/O, VR,surgery

TOUCH


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Information Processing

Three major systems of human informationprocessing :1. Perceptual (read-scan)

Memory structures Sensory buffer - Holds fixed image of outsideworld

long enough for some analysis .

Processes - info goes to brain for moreprocessing

e.q. Pattern recognition Uses context & Knowledge


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Cognitive (Think)

Cognitive model

How does it work?

Capabilities Range of movement, reach, speed,

strength, dexterity, accuracy

Often cause of errors

Wrong button Double-click vs. single click

Principles Feedback is important

Minimize eye movement

Mot or Syst em


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MEMORY

Four types

Perceptual buffers

Brief Impressions

Shor t-term memory

Conscious thought, calculations

Intermediate

Storing intermediate results, future plans

Long-term

Permanent, remember everything ever happened to us


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Memory Charac t e r i s t i c s

Things move from STM to LTM byrehearsal & practice and by use in context

We forget things due to decay and

interference

Unclear if we everreally forget something Lack of use

Similar gets inway of old

Exercise


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Observations

Users focus on getting job done, not learning to effectively use system

Users apply analogy even when it doesnt apply

People are more heuristic than algorithmicTry a few quick shots rather than plan Resources simply not available

People often choose suboptimal strategies for low priority problems

People learn better strategies with practice


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Problem Solv ing

Storage in LTM, then application

Reasoning

Deductive-

Inductive-

Abductive-

If A, then B

Generalizing from previouscases to learn about new ones

Reasons from a fact to the

action or state that caused it

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