In the previous post we defined usability. But in reality, several formal and informal definitions exist. Although, even if the definition is up for discussion, we can definitely experience it. For example, it’s easy for us to figure out when something lacks usability. In a 2004 study (1) , it was evaluated that a system that lacks usability can be characterized by:
- Existence of workarounds – because the interface is difficult or does not match workflow in the real world, users develop workarounds to compensate for the inadequacies of the system
- Low usage levels – Users use the system as little as possible.
- Dissatisfaction – Users, and particularly novices, will find the system difficult or frustrating to use
- Rework or double-handling – Inefficient design often means that the same data may need to be entered or read more often than is necessary.
These characteristics of lack of usability were derived after thorough research on how people experience the use of a product. Similarly, the characteristics of usability can also be derived based on research of user experience. However since there are multiple credible and significant studies done, each with their own empirical and statistical evidence, the characteristics often differ based on their objective definition of usability.
Ultimately, based on the individual objective definitions, we can derive specific principles of usability. Ultimately, these principles of usability give us a template to evaluate whether a product is usable, by comparing aspects of the product to a list of practices and principles conventionally required for us consider any product as usable.
We call this type of evaluation a Heuristic Evaluation. In order to understand how to conduct a heuristic evaluation, it would be best to understand which template to use. For example, Consider the Nielsen Heuristic Evaluation (2):
- Visibility of system status: The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
- Match between system and the real world: The system should speak the users’ language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
- User control and freedom: Users often choose system functions by mistake and will need a clearly marked “emergency exit” to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
- Consistency and standards: Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
- Error prevention: Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
- Recognition rather than recall: Minimize the user’s memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
- Flexibility and efficiency of use: Accelerators—unseen by the novice user—may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
- Aesthetic and minimalist design: Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
- Help users recognize, diagnose, and recover from errors: Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
- Help and documentation: Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user’s task, list concrete steps to be carried out, and not be too large.
The set of principles of usability are highlighted in bold. this set was originally developed in 1990 by Jakob Nielsen and Rolf Molich, later refined by Nielsen in 1994. Although many other heuristics evaluations have developed, the Nielsen usability principles for heuristic evaluations are very well-known and credible.
Although heuristic evaluations are a great way to evaluate the usability of a product, it does come with disadvantages (2).
- It requires knowledge and experience to apply heuristics effectively.
- Trained usability experts are sometimes hard to find and can be expensive.
- You should use multiple experts and aggregate their results.
- The evaluation may identify more minor issues and fewer major issues.
Due to the disadvantages heuristic evaluations may present, they are often used in the earlier stages of usability testing. They produce quick and inexpensive feedback to designers earlier in the design process. They could also help designers discover potential corrective measures.
(1)https://infodesign.com.au/usabilityresources/articles/technicalcommunicators/
(2) https://www.usability.gov/how-to-and-tools/methods/heuristic-evaluation.html
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