Heuristics are general rules used to describe common properties of usable interfaces [13]. During a heuristic evaluation, heuristics help evaluators focus their attention on aspects of an interface that are often sources of trouble, making detection of usability problems easier [1]. Originally heuristics were developed with the goal of making the method of heuristic evaluation easy to teach [14]. This is an important aspect of discount usability engineering which enables the method to be widely used.
People conducting evaluations may have a tendency to use rules listed in typical guideline documents. However, people need to be cautious with relying upon guidelines because they are:
Current collections of usability guidelines typically have a thousand rules to follow. The volume of these documents can seem intimidating to developers and make locating relevant guidelines an arduous and tedious task. This may mean it is not consulted during user interface evaluations.
For the discount method, Nielsen advocates cutting down the number of guidelines to just 10 rules, relying on a small set of broader heuristics [12]. In terms of guidelines, these heuristics can be considered a small set of very general design guidelines. These principles can be used to explain a very large proportion of the problems observed in user interface designs. The following are a set of general heuristics developed by Nielsen and Molich [12].
Detailed explanation of each heuristic is provided because an evaluator must have an understanding of these heuristics before they can be applied during a user interface evaluation.
There are two important issues that must be considered when using the above heuristics. First, by no means are these only ones that can be used during a heuristic evaluation. If necessary, more detailed heuristics that apply to a specific domain of user interfaces can be generated to supplement these general heuristics. Second, a good system cannot always accommodate these heuristics. Compromises between satisfying a particular heuristic and developing a good system will occur depending on the objective of the system.
Since these heuristics were developed, Nielsen [9] has performed a factor analysis to develop a revised set of heuristics These new heuristics contain contributions from other sets of guidelines and also incorporate changes due to the evolution of heuristic evaluations.