Blood, Bile and Phlegm
To the ancient Greeks, a person's general style of behaviour was an integral part of their general health. They believed that the body contained four fundamental liquids (called humours) based on the four elements of fire, air, water and earth. When one of these humours became dominant over the others, it was thought to effect the person's mood and general approach.
The four humours, blood, yellow bile, phlegm and black bile, were each believed to be responsible for a different type of behaviour. An excess of blood made a person sanguine, yellow bile resulted in a choleric nature, phlegm, naturally, produced a phlegmatic outlook, and black bile was associated with melancholia.
These theories, first set down in a systematic way by Hippocrates, remained in use until the middle ages. We now know, of course, that they have no basis in medical fact, but what the Greeks had almost incidentally achieved was the first systematic method of describing individual types of people. So successful was their approach that, even today, the words 'humour' (meaning 'mood'), 'sanguine', 'phlegmatic' and 'melancholic' are still in common use.
Thankfully, modern profiling does not rely on measuring the amount of yellow bile in a person to determine their style, but the ideas behind it can, indirectly, be traced back to Hippocrates' theories.
Carl Gustav Jung
There are many modern theories of personal behaviour based on the idea of four individual factors. Perhaps the most influential of these is to be found in the work of the Swiss psychologist, Carl Gustav Jung. He defined personalities as belonging to one of four different types; Sensing, Intuitive, Feeling and Thinking.
The definitions of these types are rooted in Jung's lifelong work on the unconscious mind, and need not concern us here. They are important because they represent one of the first serious attempts to map the human personality by a modern psychologist. Tests based on Jung's work are still available today.
It was Jung's opinion that people instinctively understand behaviour in terms of a set of four elements (his four types being one example of such a set, and the four humours of the Greeks being another). These groups of four (technically called tetralogies) underlie a very large number of assessment techniques.
The Emotions of Normal People
In the early 1920's, the flamboyant American psychologist William Moulton Marston developed a theory to explain people's emotional responses. Until that time, work of this kind had been mainly confined to the mentally ill or criminally insane, and Marston wanted to extend these ideas to cover the personalities of ordinary individuals.
"...this book is devoted to description of normal emotions which are so commonplace and fundamental in the every-day lives of all of us that they have escaped, hitherto, the attention of the academician and the psychologist."
William Moulton Marston
The Emotions of Normal People
In order to test his theories, Marston needed some way of measuring the personalities he was trying to describe. His solution was to develop his own test to measure four important factors. The factors he chose were Dominance, Influence, Steadiness and Compliance, from which DISC takes its name.
In 1928, Marston published his findings in a book entitled The Emotions of Normal People, which included a brief description of the test he had developed.
The Development of DISC
In common with many similar tools (including the IQ test), DISC first came to prominence in the military - it was widely used as part of the US army's recruitment process during the years leading to the Second World War. Having proved its value, it gradually came to be used in a more general recruitment setting.
In those early times, the use of DISC was limited in the commercial sector. To be used effectively, it needed considerable expertise, and this made it expensive. In the days before computers, even the translation of a person's questionnaire answers into a DISC profile was an arduous and complex task.
The advent of the personal computer has made DISC universally accessible, because results can be compiled and interpreted automatically. DISC has finally become a cost-effective solution for everyone, and has grown to become probably the most widely used behavioural assessment tool in the world.