Poka Yoke means mistake-proofing: changing a step so the error becomes impossible, or so that making it is immediately obvious. What distinguishes it from training is that it does not depend on anyone being careful.
Prevention makes the error physically impossible — a connector that only fits one way, a form that will not submit with a field empty, a fixture that will not close on a reversed part. Detection allows the error but surfaces it at once: a weight check catching a missing component, a checksum, a colour mismatch. Weaker, and often the only option available.
The case for it rests on human attention being an unreliable control. People performing a repetitive task correctly thousands of times will still err occasionally, and responding with retraining assumes the cause was ignorance. It usually was not. Poka Yoke treats the error as a property of the design rather than of the person — which is also why a cause analysis ending in “operator error” is an unfinished one.
Mechanisms that add friction get bypassed. A check that slows the work will be worked around within weeks whatever the policy says; the ones that survive make the correct action easier than the incorrect one.
