The Knowdell Career Assessment instruments was developed by the late Richard 'Dick' Knowdell in 1977 to meet a need in the career assessment space. At that time (& even now), many tools were developed mainly for use by psychologists and required a high level of preparation by those wishing to administer such tools.
When Dick developed the cards, his thinking was that career assessment tools have to be non-threatening, easily administered with results that yield high levels of relevance for clients.