Appliance Design - September 2007 - (Page 48) INDUSTRIAL DESIGN access door on a photocopy machine disengages an interlock switch that is located at the bottom of the door. Closing the door is supposed to re-engage the switch so the machine can be restarted. The potential problem is that the user closes the door by pushing on the top part, which is closest, and the door shuts in a way that leaves the bottom part slightly, but not noticeably, ajar because of the door’s springiness. (See Fig. 1.) The result is that the interlock switch doesn’t make its connection and the machine won’t restart. By realizing the users will not do what you want them to do, namely, push on the door at the position of the switch, a designer can prevent the problem by relocating the switch at the top of the door and/or make the door more rigid. That creates a forgiving design that prevents the user action from being an error. Issue 2. Expectations for user memory. The trap: Assuming the user will learn from a mistake. “They’ll only do that once” is a response when asked about a situation where the user forgets to take an action and the unintended outcome is serious. It is true that people may not repeat an erroneous action if the opportunity for the same error presents itself shortly after the first error occurrence and if the opportunity continues to arise frequently. However, when a significant amount of time passes, most people will not be able to remember how to do the task correctly again. Besides the time factor, interference from another experience can cause the memory to be faulty. For instance, the erroneous action on product A may have been the correct action for a similar task recently performed on product B. Example: Consider these relatively infrequent scenarios — changing the time on an answering machine, advancing the date on a watch, modifying a preference setting in a software application. Those are examples of procedures that must be done a particular way. Human memory may not recall the exact procedure because there are many ways for an error to occur — incorrectly performing a step, omission of a step, addition of a step, or transposition of steps. The design purpose here is to make an operational procedure forgiving and provide timely feedback so that ensuring correct performance doesn’t excessively tax long-term memory. Issue 3. Reliance on instructional material. The trap: Failure to reduce complexity by assuming the operating instructions will make everything clear. Finding a procedure or a particular answer in a manual or online help takes time, and most users will not want to invest extra time to use a product. Instead, they will perform trial-and-error first and read instructional material only out of necessity. Even that may not happen if the written manuals are not readily available, as is so often the case. Finally, the instructions won’t help if they aren’t written in an understandable way. Like the product itself, the instructions need to be designed for readability and understandability. Issue 4. Passive data collection. The trap: Assuming that a lack of complaints means that the design worked well. No news is good news. An absence of formal complaints does not mean the customer didn’t have any. Rather than using words, people may choose to convey their displeasure by actions such as giving www.applianceDESIGN.com 11/7/06 11:26:50 AM For more Information Enter 132 48 applianceDESIGN AD12064Port.indd 1 September 2007 http://www.pepiusa.com http://www.pepiusa.com http://www.appliancedesign.com
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