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.