At the ophthalmologist recently, preparing for cataract surgery, I watched the technician making and recording dozens of measurements. As she did, she spoke each one out loud.
She apologized, and I told her I'd just read about the Japanese practice of shisa kanko (literally ‘checking and calling’), in which a person points to and names a task while performing it. It started on the trains.
As the sleek shinkansen bullet train glided noiselessly into the station, I watched a strange ritual begin. During the brief stop, the conductor in the last carriage began talking to himself. He proceeded to perform a series of tasks, commenting aloud on each one and vigorously gesticulating at various bits of the train all the while.
It's an error-prevention drill that railway employees here have been using for more than 100 years. Conductors point at the things they need to check and then name them out loud as they do them, a dialogue with themselves to ensure nothing gets overlooked.
And it seems to work. A 1994 study by Japan’s Railway Technical Research Institute, cited in The Japan Times, showed that when asked to perform a simple task workers typically make 2.38 mistakes per 100 actions. When using shisa kanko, this number reduced to just 0.38 – a massive 85% drop.
Pointing and calling gets multiple senses in action: It requires co-action and co-reaction among the operator's brain, eyes, hands, mouth, and ears.