A2 OCR ICT - Human-Computer Interface (HCI)

Many devices use HCI to enable the user to complete tasks, e.g. mobile phones, sat nav & washing machines.

An Apple iPhone uses a GUI (Graphical User Interface) as the main means of HCI. They can rearrange the icons they see and also delete/add their own icons to the GUI.

Some sat nav devices use natural-language HCIs which lets a user input the address and postcode that they need to travel to by speaking to them. The satnav uses speech as an output to direct the driver to their destination.

As technology advances, more devices begin to use different HCI methods. The designers of these devices has to ensure that the HCI is appropriate to the tasks that the users need to complete and the advances in technology do not make the devices incapable of delivering their main function.

A user perceives input from sights and sounds taken from the user interface. Most users have preconceived ideas that they will draw on when using the interface. For example:

Graphic/text in red will have a perceived idea that it will mean 'stop'.

Graphic/text in green, based on perception of user, indicates 'go'.

Positive sound response makes user percieve the sound as 'happy'.

Negative sound response makes user perceive the sound as 'sad'.

If user hears a 'sad' sound, then perception will be that they have done something incorrectly/cannot correctly use the system.

If user hears a 'happy' sound, then perception will be that they have done something right/using the system correctly.

Interface designer needs to consider attention span, as most users have a short attention span.

Most important information on the screen must be obvious with screens clearly labelled, as well as any area where data/info has to be inserted by the user. Pop-up messages also help keep a user's attention.

Flashing graphics, and sounds can also be used to attract user's attention to an action on the screen. The features must be used sparingly as too many features detract from the use of the screen. Also, the attention span may become shorter.

If the screen is permanently filled with features, then user can become confused and feel uncomfortable with the screen.

Most screens include menus and sub-menus. Must remain consistent (same place on screen, words used should mean the same on the screen). Layout must be consistent (buttons should be in the same place). Consistent colour scheme.

Users often use the same screen on a day-to-day basis, so it is easier to remember actions required to use the interface. Some parts may be used infrequently and for which memory can't be relied on. Designer must ensure screens are easily used.

Consistent and uncluttered pages help actions required to use the interface are held in the user's short-term memory.

If user has pre-existing knowledge, then designer must consider existing knowledge that enables them to use less familiar screens.

If designer has considered and used consistency between screens, then helps to recall the skills and knowledge required to effectively use the interface. This increases speed at which the user learns to use the interface.

One major consideration while designing an interface is how quick and easy to learn it is. Interface must draw on previous experience of the user. Achieved by consistent use of colour, screen layouts and menus.

On-screen help in the form of pop-up messages or an easy-to-use help feature helps user to learn the interface more quickly. Messages need to be helpful and assist a user to easily correct their errors/learn how to complete an unfamiliar task.