Human Computer Interaction
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Human computer interaction (HCI) is defined as the study, planning and design of how a user will interact with the computer. It is a discipline that incorporates computer science, behavioral sciences, design and many more disciplines. This interaction between a user and the personal computer occurs at the user interface which is comprised of softwares and hardwares. The Association for Computing Machinery defines Human Computer Interaction as “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.” The overall goal of HCI is to meet the user satisfaction.
The flow of information between the user the computer is refereed to as the loop of information which has several aspects which include:- Task Environment which are the conditions and goals set upon the user, Machine Environment which is the environment that the computer is connected to, Areas of the Interface which comprises of non-overlapping areas which involves processes of the human and computer not related to interaction and overlapping areas which involves processes pertaining human interaction, Input flow which comes from the user, Output flow which comes from the computer environment and finally feedback which is the information through the interface that evaluate, moderate and confirm processes that arise from the user through the interface to the computer and then back (Plaisant & Shneiderman, 2005).
Persons designing interactive systems are well aware that they have to come up with a design that effective in facilitating HCI. There exist guidelines for designers’ in form of: - specific and practical guidelines, middle level principle and high-level theories and models. The practical guidelines provide information regarding design problems, caution against dangers and provide helpful reminders based on wisdom gathered for a while. The Middle level principles are useful in analyzing and comparing design alternatives. Developers of high level theories and models aim at describing objects and actions with consistent terminology to enable one to comprehend explanations for effective communication and teaching (Plaisant & Shneiderman, 2005).
Principles of user Interface Design aims at improving the quality of user interface design. The principles that are currently in use are:-
The structure principle which requires that, the user interface must under all circumstances, ensure that related things are put together and unrelated things are separated, differentiate dissimilar things and make similar things to resemble one another. Basically, it is concerned with overall user interface architecture. The simplicity principle is concerned with making communication easier between the user and the computer.
The visibility principle ensures that all needed options and materials necessary to perform a given task are visible without any sort of distraction. Unnecessary information that can cause such of interference should be avoided.
The feedback principle which ensures that constant updates are always conveyed to the user in case of any change, errors using clear language that is easily understood by the user. The tolerance principle whch calls for a flexible and tolerant design which is able to reduce cost of mistakes prevents errors and is able to interpret all reasonable actions.
The reuse which requires the design to be able to reuse internal and external components and behaviors’ be consistent with a purpose which is essential in saving the user from rethinking and remembering the already performed tasks. Under the structure principle, a number of rules should be observed when designing a Human Computer Interface.
Controls should be arranged on screen in the order in which they will be used.
Many things that make up the Human Computer Interaction are interrelated in hierarchy manner and they can ideally be made to appear that way. Things that should be considered when arranging controls in the order in which they will be used include: - Make it possible for the user to see the structure of the data, the hierarchies should be easy to understand and they should also be easy to traverse provided that the user knows the right position of the control in the hierarchy (Shelton, 1999). When constructing these hierarchies, it is important to show the controls in a trre0like structure. Designers should try to keep all the nodes at a given depth from the root in the same line, plane or arc which emphasizes their parallelism.
Also make it easier for the user to open and close non-leaf nodes in order to give him control over how much of the hierarchy is visible at any one moment. Balancing between the demands of having a dense, fully-visible structure with the ability to look at the details of individual nodes is very important when designing HCI. One area where this issue has been taken care of is in the use of panning and zooming and use of patterns such as Short Description and Optional Detail on Demand. This rule is a good one since it enables the user to move from one control to another without much wastage of time (Shelton, 1999).
Controls offering similar functions should be grouped together
Many items do exist that facilitate the interaction between the user the and the computer and some of this items of this items are very closely related to each other and therefore grouping of this items together facilitates effective use of the computer. The big problem is on how to organize these items together. The forces acting under this rule are that, large and undifferentiated masses of things can be at times become difficult to figure out more so when they are been seen for the first time, since the items are part of a coherent task, this implies that they can not be placed on another working surface and people always have an assumption that visual coherence always exists where there is semantic coherence (Tidwell, 1999).
Closely related items can therefore be grouped together, grouping them in hierarchy of groups if necessary. If possible, try to keep the number of things in a given group to at least ten or fewer. Also it is important to use repetition and symmetry to avoid chaotic visual representation of the groups. It is also important to avoid making the groups to be arbitrary, but be a clear indication of what is being shown. One of tthe thing that have contributed in making of visual grouping look good, is the use of long enough text boxes that are able to fit all the groups making them visible (Einstein, 1996).
If the same controls appear on several related screens they
Should be in the same position on each screen.
Improper management of similar controls that are located on different screens can become a critical obstacle during navigation. Placing these controls on the same location on each screen enables the user to navigate efficiently across all the screens and remains oriented in the program as he moves from one screen to the other (Marlin, 1999). For easy navigation, the user is required to understand what to do next know the state of the program, location and understands how to derive to the location. Multiple screens may be presenting either adjacent to each other or separated by splitters or stacked on each other and denoted by tabs. In a case where adjacent screens are in use, navigation problem can be solved by placing useful supporting functions directly adjacent to the primary work or display area. Placing a control at a specific location on all the different screens enables the user to go direct to the control when navigating (Marlin, 1999). On many screens you find that, the icon for my net work places is strategically positioned which enables the user to accesses other connected computers without much struggle. The rule therefore makes it easier for the user to navigate from one screen to another without getting disoriented.
Controls that are used frequently should be easy to find
Good organization of frequently used tools, paletters and functions is very vital for easy navigation. It also minimizes extraneous mouse movement that can cause user annoyance and fatigue and at worst repetitive stress injury. It is therefore important when designing HCI to group tools that are used frequently and in conjunction with each other together. One way to achieve this is to provide these controls on toolbars, paletters or other equivalents to these two. Menus should actually be made special for these types of controls (Chen, 2001). The rule makes the user to accesses the controls much quickly with minimal wastage of time.
Some controls should not be placed near each other
This requires that appropriate mapping of controls to functions be done correctly. This is influenced by the relationship between controls, the things that are affected by individual controls and final results for the controls. Poor mapping is observed when controls interfere with each others function or fail to relate visually or symbolically with each other. Poor mapping therefore requires the user to stop working and think first about the relationship between the controls which actually breaks the flow of an operation. Poor mapping of controls increases the cognitive load for users and can result in potentially serious user errors and therefore this rule is important in safeguarding users from unnecessary errors (Helander & Prabhu, 1997).