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HUMAN COMPUTER INTERFACE

HUMAN COMPUTER INTERFACE: Is defined by American Computing machine (ACM) as a discipline
concerned with the design, evaluation on and implementation of iterative Computing system for human
use and with the study of major phenomena surrounding them.

HUMAN COMPUTER INTERACTION: Is also refers to as Human Machine Iteration (HMI), Man
Machine Iteration (MMI) or Computer Human Interaction (CHI).

GOALS
1. Designing novel interface there by optimizing design for a designed property
2. Implementing interface
3. Evaluating and comparing interface with respect to their usability and other designed
properties
4. Studying human computer use and its implication
5. Models and themes of HCI use as well as conceptual framework for the design of computer
interface.

VISUAL SYSTEM
 Visual perception: The information received by the visual apparatus must be faltered and
passed to the processing element which allow us to receive coherent scenes, relative
distance and differentiate color.
 Perceiving size and depth: Perception of size relies on factors other than the visual angle
from which the individual views the object from.
 Perceiving brightness: The luminance of the object is dependent on the amount of falling
on the surface and its reflective properties.
 Perceiving color: Discriminating between colors varies with individuals and sexes.

LIMITATION
A limitation of the human visual system is that the ability to interpret and exploit our expectations
can be used to resolve ambiguity or create optical illusion.

SENSORY MEMORY
The sensory memory acts as a buffer for stimuli received through the senses. It has 3 channels.

1. Iconic (visual stimuli): characterized by the presence of image after stimuli has been removed.
2. Echoic (sound): the ability to ascertain the direction from which a sound originates from.
3. Haptic: concentration of the mind on one out of a number of competing stimuli.

SHORT TERM MEMORY

The memory used to store information where is only required fleetingly. It has a limited capacity.

LONG TERM MEMORY

The main memory resource of the humans, it stores factual information, experimental knowledge and
everything we know.

HUMAN PROCESSING
Thinking: can required different amount of knowledge

Reasoning: is the process by which we use the knowledge we have to draw conclusions or infer
something new about the domain of interest.

Problem solving: is the process of finding solution to an unfamiliar task, using knowledge we have.

THE INTERACTION
Understanding how the human uses the computer as a tool to perform or support a task.

1. Batch input: the user provides all the information to the computer at once and leaves the
machine to perform a task.
2. Direct manipulation: this involves using the various input devices to get feedbacks
3. Virtual reality: this enables continuous speedy flow of interaction as the machine senses or
perceives the uses action (movement) and responds.

BASIC TERMINOLOGIES ASSOCIATED

With interaction models
1. Domain: a domain defines an area of expertise and knowledge on some real-world activity.
2. Task: task are operations to manipulates the concepts of a domain
3. Goal: is the designed output from a performed task
4. System language: this is referred to as the core language
5. User language: this is referred to as the task language.
 MODELS OF INTERACTION
The use of models of interaction can help us to understand exactly what is going on in the
interaction and identity tools of difficulty.

NORMAN’S MODELS OF INTERACTION

This is most influential to HCI because of its usefulness to our intuitive understanding of the
interaction between user and computer. The user formulates a plan of action, the action is the
executive by the computer interface.

Norman’s model: is a useful means of understanding the interaction in a way that is clear and
intuitive. It allows more detected empirical and analytic work to be place within a common
framework.

The interactive cycle is further into 7

1. Establishing the goal

2. Forming the intension
3. Specifying the sequence
4. Executing the action
5. Perceiving the system state
6. Interpreting the system state
7. Evaluating the system state with respect to the goals and intentions.

INTERACTION FRAMEWORK MODEL

This model was developed by Abowd and beale and it provides a more description of interaction by
including the system explicitly and break it into four components.

 Articulation
 Performance
 Presentation
 Observation

OUTPUT

INPUT

Presentation and Performance = core

Observation and articulation = task

ASSESSING OVERALL INTERACTION

The interaction framework is presented as a means to judge the overall usability of an entire
interactive system.

ERONOMICS
Is the study of the physical characteristic of the interaction. It deal with how controls are designed the
physical environment in which interaction takes places, and layout and physical quantities of the
screen.

USER INTERFACE
An interface is a set of commands or means through which a user communicates with a program. It is
visual part of computer application or operating system through which a user interacts with a
computer or a software.

USER INTERFACE GOODS AND PROPERTIES

The goal of user interface design to make the users interaction as simple and efficient as possible
intern of accomplishing user goals (user centered design).

PROPERTIES OF USER INTERFACE

1. Clarity
2. Discriminating
3. Consciousness
4. Consistency
5. Detectability
6. Legibility
7. Comprehensibility

PRINCIPLE OF USER INTERFACE DESIGN

1. The structure principle
2. The simplicity principle
3. The visibility principle
4. The feedback principle
5. The tolerance principle
6. The reuse principle

TYPES OF USER INTERFACE

1. Command line
2. Natural language
3. Menu driven
4. Form based
5. Graphical user interface
 GRAPHICAL USER INTERFACE (GUI):
Are sometime also referred to as WIMP because they use Windows, Icon, Menus an Printers.

ELEMENTS OF A GUI
1. Windows
2. Icons
3. Menus
4. Pointers
5. Dialog boxes

ESSENTIAL GUI DESIGN PRINCIPLE

GUI design is a fundamental aspect of creating user friendly digital product. It is the reason you know
to click on a button or swipe in a particular direction.

PRINCIPLES
1. Aesthetically pleasing
2. Clarity
3. Compatibility
4. Comprehensibility
5. Configurability
6. Consistency
7. Control
8. Directness
9. Efficiency
10. Familiarity
11. Flexibility
12. Forgiveness
13. Predictability
14. Recovery
15. Responsive
16. Simplicity
17. Transparency
18. Trade-offs

GRAPHICAL USER INTERFACE (GUI) GUIDELINES

1. Know the user need/goals
2. Keep everything simple and neat
3. Easy user navigation
4. Don’t over stuff with details
5. Make it familiar
6. Screen layout and relationship
7. Readability

COGNITIVE WALK THROUGH

Walk through require a detailed review of a actions refers to the steps that an interface will
require a user to perform in order to accomplish some known task.

1. A specification or prototype of the system. It doesn’t have to be complete, but it should be

fairly detailed
2. A description of the task the user is to perform on the system.
3. A complete, write list of the actions needed to complete the task with the proposed system.
4. An indication of who the users are and what kind of experience and knowledge the evaluators
can assume about them.

HEURISTIC EVALUATION
Is a guideline or general principle or rule of thumb that can guide a design decision or be used to
critique a decision that has already been made.

NIELSEN’S TEN HEURISTICS ARE:

1. Visibility of system status
2. Match between system and the real world
3. User control and freedom
4. Consistency and standards
5. Error prevention
6. Recognition rather the recall
7. Flexibility and efficiency