‘Operational verification’ is a term in operationalism, a philosophy of science. The principle of operationalism is to accept only such concepts as can be described in terms of the operations necessary to determine or prove them.
For example, ‘the length of a table’ may be defined as the number of times a measuring-rod needs to be laid end to end on the table. It was first proposed by the US physicist Percy W. Bridgman (1882–1961) in 1927 when he wrote: ‘In general, we mean by any concept nothing more than a set of operations; the concept is synonymous with the corresponding set of operations.’ It can also be stated as: A concept has no meaning unless its definition formulates performable experimental procedures. Meaning has to be defined in terms of things we can do, in operations we can perform. In this way Bridgman intended to cleanse physics of meaningless, metaphysical concepts. Although the operational method failed to establish unique and rigorous criteria for judging scientific meaning, its simplicity made it widely used. It was also taken up by behavioural psychologists in the US. Operationalism may be regarded as a variation of pragmatism or logical positivism. The latter’s central tenet is the verification principle which states that 1. the meaning of a statement is the method of its verification, and 2. a statement is meaningful if and only if it is in principle verifiable. 
Alexander embraced the concept of operational verification. In his published writings it only appears in UCL:
Thus the first procedure, which is an inhibitory act, in being linked with the other procedures, becomes the beginning of a volitionary act which involves thinking in activity and enables us to gradually change and improve the general use and functioning which is a manifestation of the nature of our reaction. By these means, as can be proved by operational verification, we are enabled in process to bridge the gulf which has for too long separated subconsciousness and consciousness in the control of reaction, and at the same time to widen the gulf between the human and the animal stages of evolution.
The use of ‘operational verification’ can been seen as Alexander’s view that his process of discoveries fulfilled scientific criteria. In UCL he wrote:
For over forty-five years my technique has been seen in operation, and it can be seen today by anyone who wishes it. Throughout these years I have been engaged in demonstrating its soundness by the continued employment of experimentally established procedures which are described in ‘Evolution of a Technique’. This being so, I may claim that I am meeting the demands for proof in exactly the same way as an inventor or scientific engineer who points to his machine and shows that it works.
In a 1941 letter he wrote: ‘If we have ordered them to get a name for all that to us is demonstrable they couldn’t have done a better job for us, could they?’ Walter Carrington also relates Alexander’s enthusiasm for the concept in his Explaining the Alexander Technique.
Dr Mungo Douglas, a staunch supporter of Alexander, emphasized the scientific method in Alexander’s process of discovery in the article, ‘A unique example of operational verification during scientific experimentation’ (1946).
It is closely related to John Dewey’s ‘instrumentalism’.
The term ‘operational verification’ has not been used in the Alexander Technique literature since Alexander’s life time, partly because scientific theory has been – and is being – redefined.
See also The science of the Alexander Technique.