202 - UI

202 - UI

1. UCD

   • What is it? UCD is an iterative methodology that puts the user at the centerof all design decisions
   • UCD Goal: to optimize a users’ experience of a system, product, or process.
   • Benefits - Economic: Decreased development costs n Increased revenue from sales
   • Benefits - Social: Increased adoption rates due to end-user buy-in n Improved user productivity
   • Negatives: Users may be wrong
   • Negatives: Users may expect disadvantages
   • Predictive Models
     • Keystroad-level model (KLM) Throughput (TP) Fitt's law
       • The keystroke level model defines and measures how long it takes to press and release a key on the keyboard (measured in words per minute)
         • Advantages - Easy to model, Can be done from just sketches
         • Disadvantages - Doesn’t model errors, Doesn’t model learning time
       • Fits Law: This scientific law predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target.
   • Descriptive Models
     • Key-action model buxton's three state model Guiard's model of bimanual skill
       • KAM Identifies the need to evaluate how a user will expect a computer system to behave or react (This is different to how it actually reacts)
         • A new user may find it difficult to understand logining in using a username and password requires 100% accuracy as its getting this data from a database

2. Needs Finding

   • Key Principle: Look for needs and not solutions
   • Diary studies, experience sampling and logging studies allow you to collect longitudinal or sporadic behaviour.

3. Prototyping

   • A concrete manifestation of a design idea, Created rapidly to test an idea, GOAL is the feedback
   • Fundamental principle - Create a manifestation that filters the quality in which designers and stakeholders are interested at a given stage
   • Economic principle - Make the possibilities and limitations of the idea visible in the simplest and most efficient way
   • Scope: Horizontal - All features, But limited functionality
   • Scope: Vertical - Selected feature, With complete functionality
   • Video Prototyping - Brings together storyboard and interface design
     • Benefits: Great communication tool, Focuses the interface design on the tasks
   • Resolution: Wireframes (Structure, Functions), Mockup ( Style, Colours)

4. Memory

   • Multi-Store Model (Conceptual Model)
   • Short Term Memory (Is Virtual)
   • Long Term Memory (Is a store)
     • Memories are not accurate
     • Recall: Triggered by brain activity (HARD)
     • Recognition - Triggered by a perception of something similar (EASY)
   • Working Memory has a limited capactity
     • Memory is highly volitale
   • Cognitive Load (Demand of a UI on cognitive resources)
     • Example: Mission Impossible Instructions
   • Goal, Execute, Evaluate (We think in the same cyclic patterns in most activities)
     • Focus of Goals not tools
       • External Aids to keep track (lists)
       • We only follow scents (Promising leads)
       • Familiar paths are better
   • Unit Tasks: We can only complete small tasks with unbroken attention
   • Nielsen’s 10 Design Heuristic
     • Visibility–Show system status, tell what’s happenin
     • Mapping–Use familiar metaphors & language
     • Control & Freedom –Provide good defaults & undo
     • Consistency–Use same interface and language throughout
     • Error prevention –Help users avoid making mistakes
     • Recognition -Make information easy to discover
     • Flexibility & Efficiency–Make advanced tasks fluid and efficient
     • Minimalism–Provide only necessary information in an elegant way
     • Error recovery–Help user recognise, diagnose and recover
     • Help–Provide proactive and inplace hints to guide users
   • Milers Law: The average person can only keep about 7 (Plus, Minus 2) pieces of information in their working memory

5. (MHP) People as information processor: 3 Steps (Perceptual, Cognitive, Motor)

6. Perception

   • There is always too much information to take in, thus we use attention to filter it
     • Selective Attention: Concentrate on 1 task, we are very selective on what we focus on, Limits our ability to track all events
     • Divided: Split between tasks, can be harder to complete tasks
     • Directing our attention via: Exogenous AND Endogenous (External, Internal)
   • Biased based on expectation
     • Buttons are often clicked without looking carefully, based on past experience
   • We are drawn to see structure
   • 2 Ways we gather information: Attentive - Gathering from a small central area of our visual field
     • Preattentive - Detecting visual properties in the wider field

7. Conceptual Models

   • Instructing - Issuing Commands and selecting Options
   • Conversing - Interacting with a system if having a conversation
   • Manipulating - Interacting with objects in a virtual or physical space by manipulating them
   • Exploring - Moving through a virtual environment or physical space
   • Which one is best?
     • What is the task? Instructions good for repetitive tasks, Conversation good for children, Direct manipulation good for DOING
     • Who should have control? Command based / Direct manipulation give user control , Agents and context aware system give control to the computer

8. Interface Metaphors

   • Commonly used to explain something that is unfamiliar or hard to grasp
   • Provides a lot of information
   • Enables transfer of skills
   • Good metaphors provide natural mapping
   • Not to be taken literally
   • When are they used?
     • To conceptualise a particular interaction style
     • To describe specific operations
     • A way to describe computers
   • Benefits: Makes learning new systems easier, Helps users understand the underlying conceptual model, Increase the diversity of users able to use the system.
   • Negatives: Break the rules, too constraining, may conflict with other design principles, limits the designers imagination

9. Direct Manipulation is an interaction style where user act upon objects that are displayed

10. Input and interaction

    • Actions:
      • Manual Actions & other possibilities
    • Input devices:
      • From Action to input (Layers, Properties sensed, encoding, transformation, abstraction)
    • Controls
      • Hard/Soft, Explicit/Implicit
    • Control-Display relations
      • Spatial, Latency, Gain, Order of control
    • Modes
      • Same Controls, multiple meanings

11. Gesture Types (Interactions)

    • Pointing: Indicating Objects and Directions
      • Ray Casting, Relative Pointing
        • Disadvantages: Inaccurate at long distance, Aching Arm (Gorilla Arm)
          • Midas Touch (Doesn't know if your pointing with the system or an external force (person ect)
    • Semaphoric: Convey Specific messages based on know volcabulary
    • Iconic: Describes paths or shapes
    • Hand Postures (Static)
    • Dynamic (Temporal)

12. Input Control

    • Semantic Matching: Predefined matching to a button or key to a function
    • Spatial Matching: Mapping the motion to a control