Complex sentence: The original developers of the personality inventory were Katharine Cook Briggs and her daughter, Isabel Briggs Myers; these two, having studied extensively the work of Jung, turned their interest of human behavior into a devotion of turning the theory of psychological types to practical use.
Split into simpler sentences: The original developers of the personality inventory were Katharine Cook Briggs and her daughter, Isabel Briggs Myers. After extensively studying the work of Jung, they turned their interest of human behavior into a devotion to turn the theory of psychological types to practical use.