sentences:  Together, problem recognition and constraint recognition explained when and why people actively seek information.Later, Grunig added Herbert Krugman's concept of level of involvement to the theory to explain the difference between active communication behavior (information seeking) and passive communication behavior (information processing).In his 1984 textbook, Managing Public Relations, and in a number of studies published before and after the textbook, Grunig further developed the theory from an explanation of individual communication behavior to a theory of publics-based in part on John Dewey's book, The Public and Its Problems.