Jun 21 2014
“Poka-yoke is a Japanese term that means “mistake-proofing”. It surfaced in the 1960s, and was first applied in the car manufacturing industry. Poka-yoke is credited to industrial engineer Shigeo Shingo.”
That IT specialists should be interested in the Poka-Yoke concept is natural. There are, however, consequential inaccuracies In the way it is described in many English-language sources, including Wikipedia.
The example given as the first Poka-Yoke is a redesign of a switch assembly process that involved presenting springs on a placeholders so that the operator would not forget to insert one.
First, having a placeholder does not physically prevent the operator from making a mistake. A classical example of a system that does is one that puts a lid on every bin except the one the operator needs to pick from.
Second, this example adds labor to the operation, which means that the preparation step of placing the springs in the placeholder is likely to be by-passed under pressure. This is why it is a requirement for a Poka-Yoke not to add labor to the process.
For the same reasons, a multi-step deletion process in a software interface does not qualify as a Poka-Yoke. If you do multiple deletes, you end up pressing the buttons in rapid succession, occasionally deleting items you didn’t intend to, while cursing the inconvenience of these multiple steps.
Having different, incompatible plugs certainly made it impossible to plug the keyboard into a port for an external disk. USB, however, was an improvement over this, because, with it, the machine figures out the purpose of the connection. A connector that you can insert in any orientation is even better. It saves you time, and there is no wrong way to plug it in. This is a genuine Poka-Yoke.
There are other, useful approaches that make mistakes less likely without preventing them outright. Don Norman and Jacob Nielsen call them “usability engineering.” They should certainly be used in user interface design, but not confused with Poka-Yoke.