The Design of Everyday Things: Revised and Expanded Edition by Don Norman

Author:Don Norman
Language: eng
Format: mobi, epub
Tags: Non-Fiction, To Read, Art, Science & Technology, Design, add to kindle
ISBN: 9780465072996
Publisher: Basic Books
Published: 2013-11-05T08:00:00+00:00

In the slip known as a description-similarity slip, the error is to act upon an item similar to the target. This happens when the description of the target is sufficiently vague. Much as we saw in Chapter 3, Figure 3.1, where people had difficulty distinguishing among different images of money because their internal descriptions did not have sufficient discriminating information, the same thing can happen to us, especially when we are tired, stressed, or overloaded. In the example that opened this section, both the laundry basket and the toilet bowl are containers, and if the description of the target was sufficiently ambiguous, such as “a large enough container,” the slip could be triggered.

Remember the discussion in Chapter 3 that most objects don’t need precise descriptions, simply enough precision to distinguish the desired target from alternatives. This means that a description that usually suffices may fail when the situation changes so that multiple similar items now match the description. Description-similarity errors result in performing the correct action on the wrong object. Obviously, the more the wrong and right objects have in common, the more likely the errors are to occur. Similarly, the more objects present at the same time, the more likely the error.

Designers need to ensure that controls and displays for different purposes are significantly different from one another. A lineup of identical-looking switches or displays is very apt to lead to description-similarity error. In the design of airplane cockpits, many controls are shape coded so that they both look and feel different from one another: the throttle levers are different from the flap levers (which might look and feel like a wing flap), which are different from the landing gear control (which might look and feel like a wheel).

MEMORY-LAPSE SLIPS

Errors caused by memory failures are common. Consider these examples:

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