Why doesn't it work and can it be fixed?

How do people identify defects?

She then had users work on household appliances in the Product Evaluation Lab, the users included both experienced handymen and people with two left hands. This way, she and her colleagues could observe how people detected, located, and isolated the defect. She also saw whether the design of a device helped them or not. She asked the test subjects to think aloud about the steps they had to take, so that she could follow along closely with the steps they considered when identifying the defect. Remarkably, our senses play a major role in detecting defects. Did the hoover make a strange humming noise? And where did that smell of fire come from?

In the lab, the test subjects were given clues by a researcher if they could not make progress. Pozo Arcos noticed that many people gave up quickly. Through the offering of advice, she also gained insights such as: What did people do with it? Did it help them? Did they manage to find out what was wrong with the device in the 40 minutes they were given? It was not a question of whether they succeeded, but how they approached it. The cautious conclusion: many devices are too complex to be able to determine what is wrong when they malfunction.

Manuals, manuals, and more manuals!

And then, of course, we come to step three of  research: the user manual. For her dissertation, Pozo Arcos studied no fewer than 150 instruction manuals from 15 brands, for various household appliances. It turned out that for many defects, the instruction manual does not offer a conclusive answer. A clogged washing machine filter? The instructions explain what to do. But it says nothing about a malfunctioning motor.