Introduction to human Computer Interaction

What the meaning of Human Computer Interaction?
Human–computer interaction is the study of interaction between people (users) and computers.
It is often regarded as the intersection of computer science, behavioral sciences, design and several other fields of study. Interaction between users and computers occurs at the user interface (or simply interface), which includes both software and hardware, for example, general-purpose computer peripherals and large-scale mechanical systems, such as aircraft and power plants.
"Human-computer interaction is a discipline concerned with the design,
evaluation and implementation of interactive computing systems for human use and with the study of major
phenomena surrounding them."

On the machine side,techniques in computer graphics, operating systems, programming languages,
and development environments are relevant. On the human side, communication theory,graphic and industrial design disciplines, linguistics,social sciences, cognitive psychology,and human performance are relevant. Engineering and design methods are also relevant. Due to the multidisciplinary nature of HCI, people with different backgrounds contribute to its success.

Design methodologies
A number of diverse methodologies outlining techniques for human–computer interaction design have emerged since the rise of the field in the 1980s. Most design methodologies stem from a model for how users, designers,and technical systems interact. Early methodologies, for example, treated users’cognitive processes as predictable and quantifiable and encouraged design practitioners to look to cognitive science results in areas such as memory and attention when designing user interfaces. Modern models tend to focus on a constant feedback and conversation between users, designers, and engineers and push for technical systems to be wrapped around the types of experiences users want to have, rather than wrapping user experience around a completed system.

The Principles
When evaluating a current user interface, or designing a new user interface, it is important
to keep in mind the following experimental design principles:

• Early focus on user and task:  Establish how many users are needed to perform the task and determine who the appropriate users should be; someone that has never used the interface, and will not use the interface in the future, is most likely not a valid user. In addition, define the task the users will be performing and how often the task need to be performed.
• Empirical measurement:  Test the interface early on with real users who come in contact with the interface on an everyday basis, respectively. Keep in mind that results may be altered if the performance level of the user is not an accurate depiction of the real human-computer interaction. Establish quantitative usability specifics such as: the number of users performing the task, the time to complete the task, and the number of errors made during the task.

Replace memory with visual information knowledge in the world.
A user should not need to retain important information solely in working memory or to retrieve it from long-term memory. A menu,checklist, or another display can aid the user by easing the use of their memory. However,the use of memory may sometimes benefit the user rather than the need for reference to some type of knowledge in the world. The use of knowledge in a user’s head and knowledge in the world must be balanced for an effective design.

Principle of predictive aiding.
Proactive actions are usually more effective than reactive actions. A display should attempt
to eliminate resource-demanding cognitive tasks and replace them with simpler perceptual tasks to reduce the use of the user’s mental resources. This will allow the user to not only focus on current conditions,but also think about possible future conditions. An example of a predictive aid is a road sign displaying the distance from a certain destination.

Human–computer interface
The human–computer interface can be described as the point of communication between the human user and the computer. The flow of information between the human and computer is defined as the loop of interaction. The loop of interaction has several aspects to it including:

• The conditions and goals set upon the user.
• The environment that the computer is connected to, i.e a laptop in a college student’s dorm room.
• Non-overlapping areas involve processes of the human and computer not pertaining to their interaction. Meanwhile, the overlapping areas only concern themselves with the processes pertaining to their interaction.
• Begins in the task environment as the user has some task that requires using their computer.
• The flow of information that originates in the machine environment.
• Loops through the interface that evaluate, moderate, and confirm processes as they pass from the human through the interface to the computer and back.