HCI P2

P2 – Explain the fundamental principles of HCI design.

Perception

Perceptions change from the developer and the users. Users are very unlikely to not understand the fine detail in a GUI and the value of positioning and colour of GUI on the desktop and how these features could affect ease of use. The developer, designer and the interviewer who interviews the clients can all be different people, so the developer and designer may not be completely aware of clients needs. Also clients may not be the users and so they won’t fully understand the requirements of all users’ needs.

Colour

Colour is a very important area which designers need to be aware of when designing GUIs. Microsoft Office uses grey as the main colour and blue for enhancing drop-down lists and title bars. A lot of users think that grey is boring and dull. However if it was changed to a different colour such as bright red it would be uncomfortable on people’s eyes, though people are affected differently by various colours.

Using the Colour collaboration above it shows which colours go with which and the developers need to choose which would be best for their GUI.

Luminance

The 3 colours in the trichromatic system are identified by 3 cells in the retina of the eyes. Theories have been developed that receptors take signals which take the form of red-green, yellow-blue and black-white. These types of signals are known as opponent colour channels because they transmit opposite colours. To display the best detail luminance contrasts should always be used.

Pop out effect

When there are many symbols and images aligning, colouring and adjusting them differently can make these images stand out from others. Making the images, text stand out is also known as a pop out effect. Our eyes detect colours using the 3 trichromatic systems, but we can be tricked into thinking that more than one colour have been used. When designing GUI which is to be used at night or in poor lighting then luminance might have to be essential.

Pattern

Pattern many developers refer it to a template but a user of the GUI and its layout would most likely think it is a picture. As an example a template is used for dialogue boxes in Microsoft, this gives the user connectedness. The Gestalt laws are used in GUI to describe pattern perception and form the rules for designs.

·         Proximity: items we see that are grouped close together.

·         Continuity: level nonstop lines are better read than fast varying lines.

·         Symmetry: symmetrical shapes are easier to see than irregular shapes.

·         Similarity: we view items that are the same as a group and items that are different as individuals.

Common Groupings

·         Fate: we view items that move together as a group.

·         Region: we view items that are enclosed together by some means, as a group.

·         Connected: we view items that are connected by continuous lines as linked to each other.

Behaviour Models

There are a number of models that predict the way in which an interface or user will behave. For example;

Predictive Models

Predictive models are used to predict how humans will interact with interfaces once it is made and sold to the public. Reaction time is the time that it takes to react to an interface – for example, how long will it take for a user to reach the mouse and click on an icon. The model for this is the KLM (Key-stroke Level Model). The Through-put is the time that it takes for the request to be executed. For example, in modern technology, the faster the processor is the better the throughput. Fitts’ Law is similar to KLM – the time it takes your arm to reach the device (for example, in a touch screen phone) is determined by Fitts’ Law.

Descriptive Models

 These types of models describe the functions of certain parts of the technology. The Key-Action Model details what the functions of each key of a technology is. For example, in a standard keyboard, each key has distinctive functions. There are also combinations of keys that are already set before the technology is given to the public. Control and S keys, for example, are the shortcut keys for saving something. The Buxton’s Free State Model (BTS) determines what kind of input techniques can be used whilst creating the interface. It should be kept in mind how users may want to interact and thus have all the options open for them.

Information processing

The concept of positioning and layering can be explained more if the objects have not been arranged correctly, then the GUI or some of it may disappear behind the main screen. The user would not know it was there or able to use it.

Information Processing

Information processing is basically how information is processed or how it will be processed and how fast it is done.

Humans as a component

It is important to remember that one of the key variables in HCI design is the human end user. This can be difficult to manage and recognise people’s needs and expectations. A risk assessment is one way to analyse task steps needed for the end user.

Human Information Processing

HIP is the way in which we understand information, evaluate it and use it. Our brains could be compared to the hardware of a computer and how our mind uses the information - the software.

Goals, Operators, Method and Selections

GOMS can estimate the time it takes for command or action to be followed. The designer identifies a goal by using a series of operators and lists the methods and selection in order to carry out the command. This way the designer can estimate the time it should take and identify any problems. The designer can then work out the best method of user interface based on the user’s requirements.

Specialist interfaces

To avoid production an interface that is not accessible for specialist uses such as for a user with a disability, you may consider designing an interface that uses voice recognition software for input or even output for the visually impaired. However, you will need to consider how easy it will be used if your user has a lisp or another speech impediment.

 For those users who both aurally and visually impaired, the best option is to use haptic technology. Haptic technology might also be the only option for someone who is severely physically challenged and unable to use their limbs. A design that enables the user to use a pointer and select the desired options could enable independence. Remote control devices can be used or a heads up display for both input and output.