One of the authors had a recent experience that provides an excellent example of how a mental set can lead to poor decision-making, and in this case, considerable expense in time and money. It began when he encountered a problem with his two-year-old desktop computer. At random times, whether he was navigating web pages, writing a document, reading a pdf, or engaging in any number of other routine operations, the screen would suddenly start scrolling, or dozens of duplicate web pages would start opening, rendering the machine uncontrollable, almost as if it had been possessed by some evil digital demon. Having purchased a premium support package, he called the manufacturer’s help desk. Thus began a three-month series of almost daily calls during which dozens of technicians conducted remote troubleshooting sessions, some of them lasting for hours. The techs tried everything they could think of, starting with updating drivers, uninstalling and reinstalling various kinds of software, and searching for and adjusting settings found unimaginably deep in the bowels of the system. Some technicians undid what others had done and assured the author that this would do the trick.  It never did. Next came reinstallation of the operating system, and later, a series of onsite technician visits who replaced the main printed circuit board and, eventually, the hard drive. Nothing worked.

Finally, at the end of his rope, and frustrated at trying to work with a computer that seemed to have a mind of its own, the author ordered a new machine. He connected it to his display, his wireless keyboard and mouse, and spent a day setting up software, downloading backed up files and doing all the other chores required when a new computer arrives. Late that afternoon, the screen started scrolling uncontrollably. After staring in disbelief at this familiar rogue behavior, the penny finally dropped: If the problem reappeared with a new computer, it must reside in another component, namely the display, the keyboard, or the mouse. He did not have a spare display, but the new system had arrived with a wired keyboard and mouse. He disconnected his wireless keyboard, connected the wired one, but the problem remained. Then he disconnected the wireless mouse, connected the wired one, and was hit head on by the stunning realization that his three-month ordeal was caused by a faulty mouse that had been soundlessly clicking and scrolling its way through his applications. When he purchased and installed a new wireless mouse, the “computer” problem disappeared and has not returned.

One technician did ask the author if he had a wired mouse available to test, but because the answer was no, the topic was dropped. The mouse might have attracted more attention if the author had thought to mention to a technician that throughout this entire episode, he was replacing mouse batteries about every 10 days. That “separate” problem was annoying enough that he had searched the internet for tips on how to prolong mouse battery life, but it did not occur to him to connect the battery problem to what his mental set told him was a computer problem. The final cost of his failure to consider that his original hypothesis might be wrong included the price of an unneeded new computer, at least 100 hours of pointless troubleshooting sessions that could have been spent in productive work, and many sleepless nights born of frustration and annoyance.