Jorge Marmion is author and director of the development project of
"DB-Examiner", which has been ranked as one of the top 100 applications
worldwide by DM Review readers in 1998, 1999, and 2000. The software has been
included in the ERWin product suite, and distributed by Computer Associates
under the name of "ALLFusion Data Model Validator." Nowadays, Mr. Marmion is the
head of the Brazilian Institute of User-Friendliness and Usability (www.ibrau.com.br) and the Latin American Usability Institute (www.ilau.org).
What is usability?
Usability is a term applied to the interaction between a human
being and any piece of equipment or mechanism: the steering wheel in a car, the
remote control of a household appliance or, in our specific area, the operation
of an application (messages and commands flowing between users and computers and
vice versa).
We can say that a given system has a high degree of
usability if:
- it's easy to learn how to use it
- it's easy to
re-learn: there is no substantial loss of knowledge about the system after not
using it for a while; its main features can be easily remembered after not using
it for a long period of time.
- Users can easily identify the features that
satisfy their information needs.
- "It looks familiar": its operation is
intuitive, and adapted to users' cognitive model.
- The time required for
accomplishing any transaction (not only with regard to the computer's processing
time, but also in terms of all the commands executed in order to conclude the
transaction) meets users' expectations.
- Users are not likely to make
mistakes, and if they do, the system guides them appropriately. Undoing
incorrect actions is easy.
- Users feel safe when using it (the system does
not give room for doubts such as "what will happen if I click here?")
An application with a high degree of usability is
"nice-looking"?
Not necessarily. The adjective
"nice-looking" has different meanings depending on the culture. However, there
is no question that the first contact of a user with a visually appealing
application is more successful, and it will probably contribute for users to
reuse it with greater pleasure. But no mater how "nice-looking" your application
is, if it does not meet the abovementioned requirements, it is going to
complicate the users' tasks and they will end up giving it up and looking for a
more practical alternative.
As an example, let us consider the interaction mechanism
for Google's users, the most widely used search engine on the Internet. The page
is very simple. There are practically no graphic elements that stand out, let
alone animation. The colors, unless those used in the logo, are basic ones. Yet,
any user who gets into the web site, without having previous experience with
other search mechanisms or even in the use of the Internet, will get what they
want in a few seconds. Next time the same user needs to do a search, they will
go back to the same site. Google is probably the greatest usability shopwindow
in the world.
Google offers a great advantage: it only performs one type
of transaction. The applications that we develop on a daily basis are usually
much more complex, and include dozens or maybe hundreds of transactions. How can
we increase transactional usability and provide users with a better experience?
This is the issue that we will be addressing in this series of articles.
Use of colors
The importance of color
According to the Institute for Color Research, studies that reveal
that "all human beings make a subconscious judgment about a person, environment
, or item within 90 seconds of initial viewing and that between 62% and 90% of
that assessment is based on color alone." Consequently, it is extremely
important that we understand the fundamentals of color in order to appropriately
define the characteristics of the different Themes object classes.
What is color?
Color is
nothing but the perception of a specific electromagnetic radiation wavelength by
specialized cells in the retina. There are two types of cells in the retina:
cones (responsible for the perception of color) and rods (that do not
distinguish color, and are responsible for night vision). Cones specialize in
capturing a certain strip of wavelengths: blue, red or green.
Wavelengths (nm)
When a photon excites the retina, the cones respond to the
excitement intensity within their sensitivity range. This information is sent to
the brain through the optic nerve, decoded and transformed into a specific
perception.
Characteristics of color
Hues refer to the predominant colors in a given mix. "Red"
or "Blue" are examples of hues.
Contrast measures the separation between
the values of a given hue:
Low
Contrast
Normal Contrast High Contrast
Brightness measures the amount of white added to the
color:
Low Brightness Normal Brightness High
Brightness
Saturation measures the amount of a specific color present
in the mix.
No
Saturation Full Saturation
By defining colors in the Themes object classes, we have
to consider:
- the emotional response to the color
- deficiencies in color perception by a
significant portion of the audience.
We will discuss this in our next
issue.