DISC theory was developed by Dr. William Marston in his 1928 book, Emotions of Normal People. When we think of theories developed these days, we might think of principles derived from charts and spreadsheets from difficult-to-replicate studies. But Dr. Marston was deeply interested in interpersonal human dynamics and not that interested in grabbing headlines for cutting-edge theories. In fact, while he's well known for DISC, he's also known as the inventor of the lie detector (which he never patented), as well as being the creator of Wonder Woman (which he developed as a composite of his real-life polyamorous wife and mistress).
Marston wanted to give people practical advice about how to manage and improve their relationships with others and their experiences in the world. He saw that expression of emotions in behavior fell into four primary types. The first letter in each of these types led to the acronym DISC:
While Dr. Marston developed DISC theory, he didn't create an assessment for people to accurately get a snapshot of their expressions of the four behaviors. That was done by many people after his studies became well-known. Personality assessments in general and DISC in particular have gained momentum and currency in recent years as people have begun to grasp the importance of understanding who we are, especially in the workplace, and how we can adapt to those who do not think and work similarly to us.
The majority of DISC assessments out there (and there are many available on the internet at varying costs), if they are properly constructed, are not value-driven. The assessment should indicate tendencies and behaviors and general patterns of behavior, not indicate whether those tendencies are bad or those behaviors are positive.
Many people can honestly say that they didn't learn anything new about themselves after taking a psychometric personality assessment, be it DISC or otherwise. That may be true, but reviewing the results of these assessments is not so much solely about you as it is about how you interact with others. Having a catalogue of your own tendencies and behaviors side-by-side with ways you can improve in relation to others creates a positive loop of self-awareness and adaptation. If you can be clearer about what your strengths are and how those are perceived and dealt with by others, you can begin to overcome obstacles you may not have realized were present. As you become more aware of your particular DISC profile, you also begin to pay more attention to how others think and act, which has its own positive side effect of being more engaged with others.
The advantage of deploying this awareness in personal relationships is probably pretty obvious, but the advantages in the workplace are even more significant and varied.
Leadership Development: Those managing teams become better attuned to how they are perceived and how those whom they manage best thrive.
Sales Training: Staff are trained to understand potential and current clients for improved results while also better understanding their own motivations and adapting company methods and mindsets to them.
Customer Service: In both virtual and face-to-face interactions, team members will have superior tools to de-escalate potentially difficult situations and cultivate customer satisfaction.
Team Development: Fellow team members don't just receive training in dealing with their superiors, but with each other, and hence working relationships can improve.
Communication Skills: Improving in one area of communication, for example, face-to-face interactions, necessarily leads to awareness and improvements in other areas, like email composition or meeting dynamics.
There's a school of thought that argues, "That's just how I am and I'm not going to change," but this ignores the research and reality that shows that interactions with others have a lot to do with the expressions of our personality. A very small but obvious related example is what is known as mirroring.
Mirroring is the subconscious imitation of gestures, speech patterns, or attitudes of others. If you are visiting family, you may find yourself using dialect, slang, and gestures that you don't ordinarily use or use in a more subdued way. This leads to neural reactions that put you more at ease and make you feel more engaged and included in a situation or conversation.
Ultimately mirroring, though subconscious, is about building rapport and a better relationship with others. Using something like DISC is simply a conscious, intentional version of what we might do with mirroring. That's why assessments can be valuable in reminding us of who we are and what we need to do and be in order to be the best selves we can be with others.