James Price Dillard is a distinguished professor of Communication Arts and Sciences Department at Penn State University. He has authored and co-authored over 50 manuscripts primarily on the role of emotion and persuasive influence. Dillard graduated in 1976 from the University of Kansas with a Bachelor's degree in Speech Communication and Psychology. In 1978, he earned his Master's degree in Communication from Arizona State University and in 1983, he received a Ph.D. in Communication from Michigan State University. Dillard is currently teaching Measurement in Communication Science and Persuasive Message Processing classes at Penn State University. His awards include the NCA Golden Anniversary Award for the most outstanding, Distinguished Book Award, Communication and Social Cognition Division of the National Communication Association and many others.

Dillard is most known in the academic world for his views on affect and persuasion. His research aims to enhance understanding of the role of emotion in persuasion and interpersonal influence.

Dillard has done many studies of the use of affect in our social and environmental interactions. He theorizes how mood and emotion guide our behavior in our everyday interactions. Dillard concludes that affect affects human behavior in three main ways:

Dillard explains how affect is "phasic" and "tonic" or baseline, each one affecting the other. Affect as "phasic" acting with emotion. If someone feels fear from a stimulus, then they run away from that stimulus. If someone feels happiness when around a certain stimulus, then they would approach that stimulus. But Dillard concludes that emotions more involved than just approach and withdrawal: "If we view emotions as phasic responses to the environment, the other side of the solution is the tonic (baseline) state of the organism. Any decision as to the appropriate course of action (i.e., engagement versus withdrawal) must depend on the resources available to the organism at the time the action is required. The experiential aspect of moods can be thought of as a readout of the operating level of the organism's various biopsychological systems."

"Affect enables organisms to address the challenges posed by interaction with the environment. One fundamental problem is how to acquire the resources that enable survival and reproduction. Social life-forms have adopted a strategy for solving that problem, which depends on cooperation and role specialization."

Dillard takes on a Darwinian perspective on affect: it evolved out of a need for survival.

Dillard concludes that mood is a complex phenomenon, but it may be simplified as being either positive or negative. If a person is in a negative mood, then his or her reactions will be skewed towards the negative. A negative mood assumes that resources are seemingly depleted and takes into account challenging interactions with one's environment. If a person is in a positive mood then one feels he has ample resources to react to environmental stimulus. Be it a positive or a negative mood, Dillard considers this state to be a person's "tonic" state, or baseline mood. When the "phasic" and "tonic" states are combined, a reaction to stimulus is considered to be natural.

"Dominance and affiliation relations are efficient means of regulating resource distribution and arguably the defining ingredients in the human experience. The communication of emotion is central to the development, maintenance, and modification of these structures."