Many usability problems are instances of what we call "conceptual gaps." A conceptual gap arises because of some difference between the user’s mental model of the application and how the application actually works.Windows 95's Click Here buttons actually create gaps!

If the gap is large enough, it can stop the user’s work. For example, a user who wants to search the web for free local concerts may not know how to formulate a query that will yield this information. The gap between the search engine’s syntax and the user’s understanding of that syntax may prevent the user from accomplishing their goal.

Even subtle gaps can cause problems. For example, we asked users to find a summary of the best mutual funds using web search engines. When users looked at the search results, they didn’t know which companies were private investment brokers and which were independent sources like Morningstar.

The Yahoo, Lycos and Magellan search engines actually "know" this distinction, but users didn’t know they could access this information. Because of this gap, users had a harder time distinguishing between objective information and biased information. It didn’t keep them from proceeding with their task, but it did slow them down.

The Failure of Conventional Up-Front Methods

Product designers have historically dealt with gaps by giving the user lots of conceptual information up front via training, "getting started" manuals and tutorials. Although these approaches are better than nothing, they often are not optimal:

Spotting Gaps

We frequently see conceptual gaps when we conduct usability tests. You may have a gap if your users:

When we observe these behaviors, we try to determine what the user expected at that point. Often, something in their background or experience with other software has shaped their expectations for the product, but they don’t realize that this product works differently. This information is the designer’s starting point.

The Risks of Ignoring Your Conceptual Gaps

Conceptual gaps may be difficult to find and fix, but ignoring them is worse. In the early PC software markets, leading products that didn’t address gaps ended up losing major market opportunities.

In the late ’80s, WordPerfect owned the word processing market on the PC. Yet the product required significant training to master its functionality. At one point, the aftermarket training industry for WordPerfect was estimated at over $750 million per year — An entire industry based on making one program easier to use.

History tells us that this can’t last. Competitors (Microsoft in this case) will identify the gaps, and build products to surpass them. Are you leaving gaps for your competition to fill? •

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