Usability has a lot to say, but I will give a brief history about the principles of this trending topic, today very recognized and well accepted in the industry.
To Hix and Hartson, usability is the combination of easy learning, high speed execution of tasks, low rate of errors, subjective satisfaction and retention of knowledge (I.e.: the user even after a long time away of a given interface, will still remember how to interact with it). For Bevan (Days, 2003) suggests that “usability” is a technical term to refer a use of an interface. According to the ISO 9241, “usability” is defined by efficiency and satisfaction of how users achieve their goals.
When we talk about usability, we are referring to how well users can use resources, in our case, softwares and websites, but can be everything, since usability can be applied to any industry which demands user interaction. “User Friend” is a well-known term to define if an interface helps the user (do not scare him), whatever if this interface it’s a website, software or game. However, “user friend” is different from usability, it’s not a definition based on scientific firmaments, if you say that an user interface is “user friend”, it has no substrate and metrics to prove, it is a vague term, and very generic. It’s better to say that an user friend interface it’s just a qualitative adjective.
Nielsen defined the term “usability” into five simple measurable attributes:
- Easy to learn;
- Efficiency of use;
- Easy to memorize;
- Rate of errors and
- Subjective satisfaction
With those attributes, it’s possible to measure the degree of usability of an interface, and become a more specific term. State if an interface has a high or low usability levels are now possible.
Note that the usability is one of the most important factors when we are talking about softwares, websites or digital games, because users must first understand the navigation of that interface before start operating/playing (main goal). Winckler & Pimenta (2002) listed some classics troubles you can eventually found yourself into when using an interface, which are:
Navigation: Symptoms – When users has problems to find the desired functionality. They don’t know how to persist the information or if they will lose it if they perform an action (navigate away for example). They have problems to input the correct data or has no clue what is going to happen afterwards.
This is a Real Media conversion tool. Though free, this software contains problems of navigation (obvious to notice!). You hardly remember the control’s position and you’ll need to read all the interface again every time you use it. And if you’re using it for the first time, you’ll need time to adapt or be a power user.
Noise: Excessive use of videos, pictures and colors that has no point. The figure below shows a website with this problem.
Technology: Browser incompatibility, operational systems and hardware (connection speed). Very common among software and games, however, there are some websites that are very limited regarding browsers like Microsoft Internet Explorer and Mozilla FireFox. The screenshot bellow shows us a website accessed via FireFox that requires Microsoft Internet Explorer to display it content. Certainly the website will have a great loss of visits and potential consumers.