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Greater Usability for GeneXus Applications Using Themes (I)

GeneXus 8.0 offers developers a new object called Themes, which can greatly enhance the usability of applications when properly used. By Jorge Marmion

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.

Related
More Usability in GeneXus Applications with Themes (II)
Greater Usability of GeneXus Applications with Themes (III)
GeneXus 8.0: More Platforms and New Devices
Greater Usability of GeneXus Applications with Themes (IV)
Usability: Contact us
Usability: Color Blindness on the Web