The Computer

Elements of Computer

• A computer system is made up of various elements
• Each of these elements affects the interaction
  • input devices – text entry and pointing
  • output devices – screen (small & large), digital paper
  • virtual reality – special interaction and display devices
  • physical interaction – e.g. sound, haptic, bio-sensing
  • paper – as output (print) and input (scan)
  • memory – RAM & permanent media, capacity & access
  • processing – speed of processing, networks

Computer Technologies

• Assistive technology can include mobility devices such as walkers and wheelchairs, as well as hardware, software, and peripherals that assist people with disabilities in accessing computers or other information technologies.
• “paperless braille”: The braille cells change as the user moves around on the computer screen.
• Braille keyboard
• The Independence Drive is a system that lets users control their wheelchair using eye-tracking software.
• A graduate student who has worked with Samsung to develop the EYECAN+ is demonstrating how this new eye-tracking mouse is working.

The Human

Understanding Users

• Who are they?
  • Individual user
  • A group of users working together or a sequence of users in an organization, each dealing with some part of the task or process.
  • Limited in their capacity to process information
  • In order to design, it is important to understand the capabilities and limitations of those we are designing for.

Human Information Processing (HIP)

• How do you interact with the outside world?
  • Input-Output channel – Vision, Audio, Touch, and Movement
• How do you remember things?
  • Human memory – sensory, short term, and long term memory
• How do you process and apply information?
  • Learning, problem-solving, reasoning, skill, error, experience, etc.

Sensory Memories

• Sensory memories are responsible for transforming environmental input into neural impulses which the short-term memory can process:
  • Iconic - Visual
  • Echoic - Auditory
  • Haptic - Touch

Short-Term Memory (STM)

• Short-term memory, or working memory, is a memory buffer that holds current and recently processed information and can manipulate it.

Short-term memory is like a mental scratch-pad that our brains use for temporary storage of information. Here’s some context for the key points mentioned:

1. Rapid Access (~ 70ms): This means that short-term memory is a fast system for quickly retrieving information. When you need to remember something for a very short period, like a phone number you just heard or an address, your short-term memory helps you access it almost instantly, within about 70 milliseconds.

2. Rapid Decay (~ 200ms): Short-term memory is also characterized by rapid decay. This means that the information stored in short-term memory fades relatively quickly, within approximately 200 milliseconds. After this time, the information is more likely to be forgotten unless it’s transferred to long-term memory.

3. Limited Capacity - 7± 2 chunks: Short-term memory has a limited capacity. The text mentions “7± 2 chunks,” which is a concept introduced by cognitive psychologist George A. Miller. It means that on average, people can hold about 5 to 9 pieces of information (chunks) in their short-term memory at a time. For example, you can remember a phone number or a list of items, but the capacity is limited, and you might start forgetting the earliest items as new ones are added.

• With rehearsal:

Long-Term Memories (LTM)

• Long-term memory (LTM) is a repository for all our knowledge with a huge or unlimited capacity.
• Two types:
  • Episodic – serial memory of events
  • Semantic – structured memory of fact, concepts, skills
• Semantic LTM is derived from episodic LTM.
• Three main activities related to LTM:
  • Storage/Remembering of Information
  • Forgetting
  • Information Retrieval

The Human Factors

Here are organized notes on the provided information using Markdown:

Physiology

• The design of devices is often affected by human physiology.
• Some constraints can be introduced and applied based on the physical build-up of the users.
• Examples:
  • Keyboard keys cannot be smaller than finger size
  • Smaller machines must use different input facilities
  • Toilet for toddlers
  • Specific door widths and heights (home, hospitals)

Reaction Time

• Human reaction times:
  • Audio signal - 150ms
  • Visual signal - 200ms
  • Pain - 700ms
• Examples of use:
  • Design of video games
  • Traffic lights
  • Phone

Movement

• Speed or accuracy of movement are important for interactive systems.
• Examples:
  • Mouse - keyboard movement (affects choice of which devices/controls operate which actions of the system)
  • Time taken to move to a target on screen
  • Careful arrangement of menu items so that frequent choices are placed first

Disabilities

• Designers must design so that disabled users can achieve maximum functionality and usability from computer systems.
• Examples:
  • Speech input and output systems (useful for blind people and those with severe motor impairment)
  • Keyboard pressing devices
  • Eye movement detection devices

Cognition

• Thinking, reasoning, problem-solving, memory
• The processes by which we become acquainted with things, how we gain knowledge, familiarity
• What goes in our heads when we carry out our everyday activities
• Involves understanding, thinking, remembering, reasoning, memorizing, attending, awareness, acquiring skills, creating new ideas.

Managing Attention

• Process of selecting things to concentrate on at a point in time
• Depends on:
  1. Users’ goals
     • If we know exactly what we want to find out, we try to match this with the information that is available
     • Interface designers need to focus attention on the users’ goals
  2. Information presentation
     • Greatly influences how easy or difficult it is to digest appropriate pieces of information
     • Interface designers need to focus attention on the right place – plan and structure the information presentation
     • Interface designers need to focus attention on the right place to avoid too much/little information

Perception

• How a person perceives what input they get through their senses
• How a person perceives what input they get through their senses
• Capabilities and limitation of visual processing and understand how we perceive size and depth, brightness, and color

Emotions

• Feelings that affect human behavior
• Emotion involves both cognitive and physical responses to stimuli
• James-Lange: emotion is our interpretation of a physiological response to a stimuli
• The biological response to physical stimuli is called affect
• Affect influences how we respond to situations
  • positive  creative problem solving
  • negative  narrow thinking
• “Negative affect can make it harder to do even easy tasks; positive affect can make it easier to do difficult tasks” (Donald Norman)
• Implications for interface design
  • Stress will increase the difficulty of problem-solving
  • Relaxed users will be more forgiving of shortcomings in design
  • Aesthetically pleasing and rewarding interfaces will increase positive affect

Errors & Mental Model

Types of Error

• Slips
  • Right intention, but failed to do it right
  • Causes: poor physical skill, inattention, etc.
  • Change to aspect of skilled behavior can cause slip
• Mistakes
  • Wrong intention
  • Cause: incorrect understanding
• Humans create mental models to explain behavior.
• If wrong (different from the actual system) errors can occur

Mental Model vs Conceptual Model

• A mental model is the representation that a person has in his mind about the object he is interacting with.
• A conceptual model is the actual model that is given to the person through the design and interface of the actual product.

Interaction

Interaction in this context refers to the process of information transfer between the user and a computer.

Interaction Model

In HCI (Human-Computer Interaction), interaction models serve as translations between the user and the system. Various interaction models exist in HCI, such as Donald Norman’s Interaction Model and Abowd & Beale’s model. A generalized Interaction Model (from Dix et al) consists of four components:

1. System
2. User
3. Input
4. Output

Additionally, there are different interaction styles (nature of the dialogue) and interaction contexts (social, organizational, educational, commercial, etc).

Donald Norman’s Interaction Model

Donald Norman’s Interaction Model divides interaction into two phases:

1. Execution: User activities aimed at making the system do something.
2. Evaluation: Evaluating whether the system did what the user wanted.

Understanding Interaction:

• If the user cannot make the system do what they want due to unclear instructions, it results in the “Gulf of Execution.”
• If the user cannot see what happened to the system after performing an action, it results in the “Gulf of Evaluation.”

The goal of good design is to reduce these gulfs.

Donald Norman’s model consists of seven stages:

1. User establishes the goal.
2. Formulates intention.
3. Specifies actions at the interface.
4. Executes actions.
5. Perceives the system state.
6. Interprets the system state.
7. Evaluates the system state with respect to the goal.

This model concentrates on the user’s view of the interface and forms an execution/evaluation loop.

Interaction Styles

1. Command Line Interface:
   • Directly expresses instructions to the computer, often using single characters, abbreviations, or whole words.
   • Suitable for repetitive tasks and expert users.
2. Menus:
   • A set of options displayed on the screen, offering visual choices.
   • Options can be selected using numbers, letters, arrow keys, or a mouse.
   • Options are often hierarchically grouped.
3. Query Interfaces:
   • Question/answer interfaces guide users through interactions via a series of questions.
   • Commonly used in information systems.
   • Query languages, such as SQL, are used to retrieve information from databases.
4. Form-Fills:
   • Used for data entry or retrieval.
   • Resemble paper forms and require sequential data entry.
5. Spreadsheets:
   • Grid-based interfaces for data entry and calculation.
   • Allows formulas to involve values from other cells.
6. Three-Dimensional Interfaces:
   • Includes virtual reality and 3D workspaces.
   • Utilizes depth cues and distance effects for interaction.
7. WIMP Interface (Windows, Icons, Menus, Pointers):
   • The default style for many interactive computer systems.
   • Utilizes windows as independent areas, icons for representation, menus for options, and pointers for interaction.
8. Windows:
   • Independent areas on the screen, can be moved or resized.
   • Contains scrollbars and title bars.
9. Icons:
   • Small images that represent objects in the interface.
   • Can be stylized or realistic.
10. Pointers:
    • Used for pointing and selecting objects in the WIMP style.

Kinds of Menus

• Menu bars (pull-down, drop-down, or fall-down)
• Contextual menus (pop-up or pie menus)

Buttons

• Individual regions on the display that can be selected to invoke actions.
• Special types include radio buttons and check boxes.

Typical WIMP Interface

A typical WIMP (Windows, Icons, Menus, Pointers) interface includes windows, icons, menus, scrollbars, title bars, buttons, and other elements. Additionally, it may have a taskbar and a notification area.

Dialogue Boxes

• Information windows that pop up to inform users of important events or request information.
• Often used for tasks like saving files, where the user specifies details in the dialogue box before it disappears.