Civil Engineering Reference
In-Depth Information
While trained searchers often like the specificity enabled by search systems that allow the entry of logical
operators (AND, OR, NOT, ADJACENT, etc.), many people have difficulty understanding the meanings
of such operators. Awell-designed relevance ranking algorithm is often an effective way to avoid requiring
the use of logical operators when entering a keyword phrase, helping to direct the information seeker's
attention to those retrievals that are likely to be most focused on the topic of interest by putting them
at the top of the list of retrievals, while still providing access to the broader set of retrievals lower in
the list in case the search engine's relevance judgments do not fully reflect the interests of that user.
Finally, structured keyword entry systems can be an effective compromise between browsing and a
simple keyword search. If the information available in a system can be categorized along several dimen-
sions, (such as the model, year, color, and cost of used cars in a database), it may be helpful to present the
user with these categories so he or she can pick from the menus of items available for each category. In
some cases, such menus can even be made context specific, so that as the user fills in one category, the
remaining choices in the other categories are limited.
Are “cause and effect” actions represented in the interface?
Each input by the user or change in the behavior of the program should be accompanied by a correspond-
ing change of its representationwithin the interface. The “current selection” (active field or object) should be
indicated with some visual contrast. The current state of the product should be displayed in a consistent,
clear, and unambiguous manner. If the product acts directly upon the “world” (such as with a process
control system), the current state of the “world” as known to the product should also be displayed clearly.
Will users be able to detect and recover from errors?
It is inevitable that someone will hit the wrong button due to a slip or mistake. Potential errors need to
be predicted, and measures to assure detection and recovery need to be identified if design changes
cannot be made to prevent these errors. Minimally, it should be possible to undo or cancel actions.
Actions that are irreversible like “saving over an existing file” should require a user to make an explicit
commitment. These safety nets will give novice users a sense of comfort, as well as supporting more effec-
tive use of the product.
Is the interface esthetically pleasing?
Keeping in mind that beauty is in the mind of the beholder, the interface should have a sense of beauty,
or at the very least not be perceived by the intended users as crude or awkward. Ask questions like:
.
Are the colors harmonious?
.
Is the type legible?
.
Are the graphics consistent?
Also note whether users have the ability to customize the display of the interface, that is, change
the colors or type font to suit their own esthetic judgments. Factors that influence the esthetics of a
product also often have an effect on usability because of their impact on the salience of key information.
24.4 Conclusions
As suggested at the beginning of this chapter, one of the hats that the designer needs to wear is that of a
psychologist, conducting initial user studies and needs assessments to define the design problem, and
attempting to determine how a given design will influence user performance as part of its evaluation.
In terms of the evaluation of a specific design, both analytical and empirical evaluations are valuable. Both
of these forms of evaluation call for expertise in cognitive and social psychology, as patterns of performance
need to be predicted a priori for analytical evaluations, and need to be detected in empirical evaluations.
To improve analytical predictions, two general approaches have been developed:
.
Cognitive walkthroughs
.
Heuristic evaluations
Search WWH ::
Custom Search