User-Centric Design – The Lessons of 3 Mile Island

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In 1979, the worst nuclear commercial power plant disaster on American soil took place in Pennsylvania. An investigation found that the mechanical failures were compounded by the initial failure of plant operators to recognize the situation as a loss-of-coolant accident. Poor training and confusion caused by ambiguously designed control room indicators were found to be at fault.

Don Norman, who coined the term “user-centered design,” was one of the experts flown in to investigate the nuclear meltdown.

In a talk he gave last week at MindFlow Design to a group of San Diego industrial designers, Norman said: “The control room and computer interfaces at Three Mile Island could not have been more confusing if they had tried.”
He explained how the linear array of buttons, switches and indicators arranged in equally-spaced straight lines may have made sense on paper to design engineers, but were not intuitive to plant operators.

Understanding the psychology behind people’s expectations, needs and behaviors is the foundation of great design. People have mental models of the way they expect things to work. Exceeding these expectations creates a sense of delight or an emotional connection. Violating these connections can create frustration or confusion.

At Three Mile Island, the failure to correctly assess user needs helped bring the plant to the brink of catastrophe. Following this incident, regulatory changes were introduced to consider human factors design in the construction of future nuclear plants.

For today’s manufacturers, the price to be paid for design oversights may or may not include potential loss of life. At minimum, such failures put eventual product acceptance and profitability at risk.

The lesson is clear for any manufacturer: make the investment in fully understanding user needs as the first step in the design process. If you do, you’ll stand a better chance of creating a winner.

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