The Psychology behind Lean Manufacturing

Introduction

In his book ‘Key Strategies for Plant Improvement’ Shigeo Shingo writes;

“When a method is familiar, we move naturally, without having to think what task should be done next or how each task should be done. Consequently, the job can be carried out without burdening the brain.
That means there is no psychological burden involved, and a worker can hum as he works.
Workers end up believing that familiar operations are easiest and therefore the best way of doing things. But is this in fact so? Lilian Gilbreth devised some “Table-Top Improvement Experiments” that help clarify this point. (Shingo 1987. P. 149 – emphasis mine).

In a letter to Alan G. and Margaret M. Robinson, cited in their co-authored paper “On the tabletop experiments of Japan”, (School of management, University of Massachusetts 1994) following an enquiry as to further details surrounding Lilian Gilbreths influence, Shigeo Shingo replied with a full set of ‘TableTop’ experiments and the following note; “As to a source reference for them, I am unable to help you, to my regret, since I do not have any written memo about them in either English or Japanese. I learned them from Mr. Horigome, my most respected teacher in industrial engineering, very long ago, probably around 1937. As far as I know, he learned them from his teacher Mr. Tsunoda, who worked at the Yokosuka Naval Arsenal and attended a lecture given by Lilian Gilbreth in the Taisho Era [1912-1926] (Shingo, S. Personal communication).

Following further research in Japan, A.G. and M.M. Robinson were able to identify six experiments, devised by Frank and Lilian Gilbreth, originally introduced to Japan via some class notes of a Japanese student of Frank Gilbreth in 1923.

For the purpose of this essay, it can be noted that Shingo alludes to the successful adoption of the lessons delivered by these experiments as a ‘psychological’ and ‘brain burden’ issue.

It can also be noted that the Tabletop experiments seem to have had a profound influence over the entire approach to management across Japan, and subsequently, the rest of the world. Lilian Gilbreth was the author of The Psychology of Management: The Function of the Mind in Determining, Teaching, and Installing Methods of Least Waste (1914).

This publication investigates the psychological aspects of scientific management, incorporating concepts of human relations and worker individuality into management principles. It is noteworthy, that in 1968, Lilian Gilbreth was awarded, in the name of the emperor of Japan, the "Third Class of the Order of the Precious Crown'' for "Outstanding contribution to the guidance and diffusion of scientific management and industrial development".