Douglas Ehninger identified four major trends that constituted the modern approach to rhetoric. First, the neo-classical school focused on recovering and adapting classical theory to the needs of the times. Secondly, psychological-epistemological-oriented theorists reconceptualized classical precepts using modern theories of behavior. Belletristic rhetoricians developed standards of instruction and criticism for the polite arts. Elocutionists narrowed their focus to the use of the voice and body in oral presentations.
During the modern period, rhetoric ceased to be viewed solely as persuasion, that is a speaker's self-conscious manipulation of his performance with a view to gaining a favorable reception for his message from a particular audience. The modern rhetorical theorists considered messages addressed to the understanding, i.e. informative ones, to be a part of rhetoric and, given the technology of the printing press, focused on the written as well as the oral medium.
Modern theorists drew upon faculty psychology to understand the audience and to classify speeches by the desired response, not by their genres such as forensic, epideictic, and deliberative used by Aristotle. The mind was conceived as being a bundle or collection of faculties adapted to particular tasks. The understanding is the most basic faculty and has the power to form and order experience by isolating and abstracting from sense data intelligible patterns. The imagination is the image-making faculty that can translate the sense data patterns into vivid and lively images. Reason is the intellectual faculty that combines the images or apprehensions of the understanding into wholes. It produces ideas by reflecting on sensory experience to trace natural relationships of correspondence and connection. The passions are the emotions. Memory is the faculty that stores information. The will expresses our determination to act.
Modern rhetoricians such as Campbell classified speeches by their desired effect on the listener: to enlighten the understanding, please the imagination, move the passions, influence the will. Proofs were categorized by the way the listener came to believe: experience, analogy, testimony, and calculation of chance or probability. They gave the primary task of invention to logic and made rhetoric's role that of framing and using proofs already established. Thus the traditional categories of invention and arrangement became fused into one category: the management of discourse.