chapter 3

the interaction

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 The Interaction
• In Human-Computer Interaction (HCI), interaction is about
how users communicate and interact with computer
systems.
• It includes how users input commands or data and how the
system provides responses or feedback.

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 Purpose of Interaction
• Enhance Usability: Make systems simple and easy to use.
• Improve Efficiency: Help users finish tasks quickly with less
effort.
• Provide Feedback: Show users the results of their actions.
• Support Accessibility: Make sure everyone, including those
with disabilities, can use the system.
• Facilitate Learning: Help users understand how to use the
system and its features.

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 Key Components of Interaction
• User: The person interacting with the system. Their needs,
preferences, and abilities influence the design.
• System: The computer or device that users interact with. It
processes inputs and provides outputs or feedback.
• Input: The actions or commands users provide to the
system, such as typing, clicking, or speaking.
• Output: The system's response or feedback to the user's
actions, such as displaying information on the screen or
playing sound.
• Interface: The medium through which the user interacts
with the system, such as a graphical user interface (GUI),
command-line interface (CLI), or voice interface.
• Environment (Context): Context: Social, work, and
personal factors that affect how users interact with a system.

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models of interaction

Norman model
interaction framework

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Donald Norman’s model (Seven
Stages of Action model)
• Users interact with computer systems by following simple
steps:
– Planning: The user decides what they want to do.
– Execution: The user performs actions using the
computer, like clicking buttons or typing.
– Evaluation: The user checks the results on the screen
to see if the actions worked as expected.
• This process repeats until the user completes their task.
The cycle has two main parts:
– Execution Phase: Doing the actions.
– Evaluation Phase: Checking the results.

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Donald Norman’s model (Cont’d)
• Seven stages
– user establishes the goal
– formulates intention
– specifies actions at interface
– executes action
– perceives system state
– interprets system state
– evaluates system state with respect to goal

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execution/evaluation loop
goal
execution evaluation
system
• user establishes the goal
• formulates intention
• specifies actions at interface
• executes action
• perceives system state
• interprets system state
• evaluates system state with respect to goal

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execution/evaluation loop
goal
execution evaluation
system
• user establishes the goal
• formulates intention
• specifies actions at interface
• executes action
• perceives system state
• interprets system state
• evaluates system state with respect to goal

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execution/evaluation loop
goal
execution evaluation
system
• user establishes the goal
• formulates intention
• specifies actions at interface
• executes action
• perceives system state
• interprets system state
• evaluates system state with respect to goal

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 Using Norman’s model
Gulf of Execution
The gap between what the user wants to do and how to do it
using the system.
Gulf of Evaluation
The gap between what the system shows and how easily the
user can understand it.
Key Point: Reducing these gaps makes the system easier to use
and understand.

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 Human error - slips and mistakes
Human Errors: Two main types—Slips and Mistakes
1. Slip:
– User knows the goal and the right action.
– But does the wrong action by accident.
– Fix: Improve the interface design.
2. Mistake:
– User chooses the wrong goal or plan.
– Happens due to misunderstanding the system.
– Fix: Help users understand the system better.

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 The interaction framework
• Extension of Norman: Interaction Framework
• The interaction framework explains how users interact
with systems using four main parts:
– User: The person using the system.
– Input: The actions or commands from the user.
– System: The computer or software processing the
input.
– Output: The system's response shown to the user.
• Each part uses its own language.
Interaction means translating between these languages.
Interaction problems happen when there are translation
issues.

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 The interaction framework
(Cont’d)

O
output

S U
core task
I
input

(a)The general interaction framework (b) Translations between components

Figure1: The Interaction Framework

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The interaction framework
(Cont’d)
• S (Core): Represents the core or the internal state of
the system.
• O (Output): Represents the output generated by the
system.
• I (Input): Represents the input provided to the
system.
• U (Task): Represents the task or actions that the user
intends to perform.

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Translation of Interaction
• Articulation: Turning the user's actions or commands
into input the system can understand.
• Observation: The user checks the system's output.
• Presentation: The system shows the output in a clear
and useful way.
• Performance: The system processes the input and
performs actions.

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Ergonomics (Human Factors)

• Ergonomics studies how physical aspects affect user

interaction. It focuses on:
– Control design: Easy-to-use buttons and controls.
– Screen layout: Clear and simple displays.
– Physical environment: Comfortable surroundings.
– Color use: Proper colors for better understanding.
– Health concerns: Reducing strain and discomfort.
• Goal: Improve user performance by considering human
behavior and system limits.

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Arrangement of controls and
displays
Logical Grouping of Controls and Displays
• Proper grouping helps users access controls quickly,
especially in safety-critical systems.
– Functional Arrangement:
– Group controls by their purpose.
– Sequential Arrangement:
– Arrange controls in the order they are used.
– Frequency-Based Arrangement:
– Place frequently used controls where they are easy
to reach.
• Tip: Design the interface so users can easily see and
reach everything without extra movement.
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 Interaction Styles
• Interaction between the computer and user is like a
conversation. The type of interface affects how this
conversation happens. Common interface styles include:
• Command Line Interface: Type commands to interact.
• Menus: Select options from a list.
• Natural Language: Use normal language to communicate.
• Question/Answer and Query Dialogue: Ask questions and get
responses.
• Form-Fills and Spreadsheets: Fill out forms or work with
tables.
• WIMP (Windows, Icons, Menus, Pointer): Use windows, icons,
and menus with a mouse.
• Point and Click: Click on items to interact.
• Three-Dimensional Interfaces: Interact with 3D spaces or
objects. 19
 Command Line Interface (CLI)
• The CLI is the first style of interactive dialog and is still
widely used.
• Users type commands using function keys (f1), characters
(cls), or full text (del file_name.txt).
• It gives direct access to the system and offers flexibility.
• Consistent commands help users learn, but different
systems can cause confusion.
• Example: Command prompt in Windows.

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 Menus
• Menus present choices clearly on the screen for easy
visibility.
• The options are organized into groups that are logical and
named appropriately.
• Menus may have multiple levels that need to be navigated
through.
• Menus can display either text or images for selection.
• The user can select options by typing, entering numbers, or
using arrow keys.

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 Natural language
• Natural language interfaces allow users to interact with
computers using spoken or written language instead of
commands.
• Natural language can be unclear because of sentence
structure (syntax) and word meanings (semantics).
• These systems can only understand certain terms within
specific areas, so users need to be aware of these
limitations.
• While building general natural language systems (ChatGPT)
is difficult, simpler systems focused on specific tasks tend to
work better.

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 Question/answer and query
dialog
• Question and Answer Dialog
– Users respond by selecting yes/no answers, choosing
from multiple options, or entering codes.
– The dialog is simple, making it suitable for beginners
and focused tasks.
– It supports only a limited range of tasks with less
flexibility.

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 Question/answer and query
dialog (Cont’d)
• Query Languages:
– Used to get information from a database.
– Uses simple phrases but follows specific rules.
– Easy for single searches but harder for complex
ones.
– Needs user experience as there’s no direct
confirmation.
– Example: Web search engines like Google.

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 Form-Fills and Spreadsheets
• Form-Fills
– Used mainly for entering and sometimes retrieving
data.
– Looks like a paper form with spaces for user input.
– Easy to navigate, allows empty fields, and has
options for corrections.
– Simple to learn and use, suitable for beginners and
experts.

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 Form-Fills and Spreadsheets
(Cont’d)
• Spreadsheets
– A grid of cells to enter values and formulas, keeping
things consistent.
– Lets users change values and formulas, mixing input
and output.
– Flexible and easy to use for working with data.

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 WIMP Interface
• A graphical user interface (GUI) where users interact with
windows, icons, menus, and pointers (mice).
• Designed to be easy to use and intuitive.
• Allows users to click on graphical elements instead of
typing commands.
• Commonly used in most computers, especially PCs and
desktops.

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 Point and click interfaces
• A single mouse click can open windows or display
information.
Example: Clicking an icon to perform a task.
• Related to the WIMP style (Windows, Icons, Menus,
Pointer), featuring a simpler, more clickable design.
• Also works on touchscreens, often using a menu-based
approach.
• Well-suited for navigation, file management, and
interacting with graphical elements.

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 Three dimensional interfaces
• 3D effects are becoming more common in user interfaces,
including virtual reality (VR) and other 3D techniques.
• Basic 3D effects involve adding shading to WIMP elements
(buttons, scroll bars) for a 3D look.
• Standard practice (shadows and highlights ) involves a light
source from the top right to enhance the 3D effect.
• Example:
– Virtual Reality (VR): Move and interact with virtual
objects in a 3D world.
– 3D Video Games: Navigate through 3D characters and
environments.
– 3D Modeling Software: Create and modify objects in
three dimensions.
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