The main goal of heuristic
evaluations is to identify any problems associated with the design of user
interfaces. Usability consultant Jakob Nielsen developed this method on
the basis of several years of experience in teaching and consulting about usability
Heuristic evaluations are one of the
most informal methods of usability inspection in the field of human-computer
interaction. There are many sets of usability design heuristics; they are
not mutually exclusive and cover many of the same aspects of user interface
Quite often, usability
problems that are discovered are categorized—often on a numeric scale—according
to their estimated impact on user performance or acceptance. Often the
heuristic evaluation is conducted in the context of use cases (typical
user tasks), to provide feedback to the developers on the extent to
which the interface is likely to be compatible with the intended users’ needs
The simplicity of heuristic
evaluation is beneficial at the early stages of design. This usability
inspection method does not require user testing which can be burdensome due to
the need for users, a place to test them and a payment for their time.
Heuristic evaluation requires only one expert, reducing the complexity and
expended time for evaluation. Most heuristic evaluations can be accomplished in
a matter of days. The time required varies with the size of the artifact, its
complexity, the purpose of the review, the nature of the usability issues that
arise in the review, and the competence of the reviewers. Using heuristic
evaluation prior to user testing will reduce the number and severity of design
errors discovered by users. Although heuristic evaluation can uncover many
major usability issues in a short period of time, a criticism that is often
leveled is that results are highly influenced by the knowledge of the expert
reviewer(s). This “one-sided” review repeatedly has different results than software
performance testing, each type of testing uncovering a different set of
Jakob Nielsen's heuristics
are probably the most-used usability heuristics for user interface design.
Nielsen developed the heuristics based on work together with Rolf Molich
in 1990.The final set of heuristics that are still used today were released by
Nielsen in 1994. The heuristics as published in Nielsen's book Usability Engineering are as follow]
Visibility of system status:
The system should always keep
users informed about what is going on, through appropriate feedback within reasonable
Match between system and the real world:
The system should speak the
user's 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.
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
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
GERHARDT-POWALS’ COGNITIVE ENGINEERING PRINCIPLES
is considered the
expert and field
leader in heuristics,
Jill Gerhardt-Powals also
developed a set of cognitive
principles for enhancing computer performance. ]These heuristics, or
principles, are similar to Nielsen’s heuristics but take a more holistic
approach to evaluation. Gerhardt Powals’ principle are listed below.
Automate unwanted workload:
o free cognitive resources for high-level tasks.
o eliminate mental
calculations, estimations, comparisons, and unnecessary thinking.
o display data in a manner that
is clear and obvious.
o reduce cognitive load
by bringing together lower level data into a higher-level summation.
Present new information with
meaningful aids to interpretation:
o use a familiar framework,
making it easier to absorb.
o use everyday terms,
Use names that are
conceptually related to function:
o Attempt to improve recall and recognition.
o Group data in consistently
meaningful ways to decrease search time.
Limit data-driven tasks:
o Reduce the time spent
assimilating raw data.
o Make appropriate use of color
Include in the displays only that information needed by the user at
a given time.
Provide multiple coding of data when appropriate.
Practice judicious redundancy.