We believe that most decisions in most instructional contexts regarding instructional communication are made by the actual instructor. Different instructors, dealing with the same curriculum and the same content, may choose to communicate with their students differently.

Given the above, this theory places the instructor at the beginning of a causal pattern. The way they communicate is projected as a major factor in student learning. Students' previous learning, their intelligence and other abilities, their temperament and personality, their trait motivation to learn, and their initial affect for the content to be studied are other causal factors in this process. These and other student factors, as well as other factors in the instructional process which are beyond the control of the instructor, produce the error component of this theory. That is, regardless of how the instructor communicates, students will vary greatly in the achievement of the intended (and unintended) outcomes of the instruction. Thus, this theory of instructional communication is not expected to predict all of the variance in instructional outcomes--it only seeks to predict that for which the instructor's communication is responsible.

Step One--Instructors' Communication Choices

This theory of instructional communication begins with the instructor's communication choices. These choices may be conscious (such as whether to use mediated technologies) or unconscious. We believe many of the actual communication choices are unconscious--the degree to which the instructor is immediate with student, the use of assertive and/or responsive communication behaviors, use of techniques to make the instruction clear and understandable for the student. However, such choices may be made consciously by instructors who have instructional communication training or have developed an understanding of such elements in another way. 

To the extent that such choices are made unintentionally, other factors are involved. This suggests other causal factors are operative. We believe these factors primarily involve the temperament and personality of the teacher. While these elements are not critical element of this theory, it is important that we consider them.
Communicator traits, including temperament and personality, have long been the subject of communication research, as well as research in psychology and psychobiology. For most of the past century, some psychologists have suggested that personality is a learned orientation. Others have suggested that these traits are genetic in origin. Over recent decades, scholars have debated about the diversity of personality traits. Most scholars now agree there are between three and eight dimensions of personality, normally referred to as "temperament." Three of these temperament dimensions have been determined to be genetically based (Gray, 1990, 1991). In 1990, Eysenck concluded that extraversion (E), neuroticism (N), and psychoticism (P) are the genetic bases of individuals' behavior. The three components measure the degree to which a person is cooperative and sociable (E), fearfully avoids (N), and is hostile or aggressive (P).

A number of recent studies employing the communibiological paradigm have determined that Eysenck's temperament variables are highly associated with several communication orientations/behaviors. These include nonverbal immediacy (Cole, 2000), socio-communicative orientation/style (Cole & McCroskey, 2000), shyness (McCroskey, Heisel, & Richmond, 2001), verbal aggressiveness (Beatty & McCroskey, 1997), communication apprehension (Beatty, McCroskey, & Heisel, 1998), and a wide variety of others (McCroskey, Heisel, & Richmond, 2001).

Eysenck's instruments in these studies are used as surrogate measures of neurobiological functioning, hence represent genetically-based brain systems. Relationships between the temperament measures and the measures of communication orientations (apprehension, shyness, verbal aggression, etc.) indicate the degree to which temperament and communication orientations stem from a common cause--brain systems. Hence, it is important to understand that it is not temperament which causes communication orientations/behaviors. Rather, the same brain systems are the cause of both temperament and communication orientations/behaviors. Psychobiological scholars suggest that the manifestation of temperament traits is primarily through "social interaction," or what would be called in this field "communication."

While there is not unanimous acceptance of the genetic explanation for personality or temperament, for the purpose of this theory it is not essential that we choose one explanation over the other. Whether temperament traits are inborn or learned, they manifest themselves though communication choices. Instructors' communication choices, then, to a large degree are manifestations of their temperament. Hence we should expect instructors' choices for instructional communication to be, at least in part, manifestations of their temperament.

Step Two--Student Perceptions

Perceptions of Instructor Communication Behaviors. Instructor communi-cation behaviors are a causal element in their students' perceptions of the instructor's communication behaviors. While in an ideal world, we might expect these relationships to be perfect, there are also many factors which may cause students to misperceive instructors' behaviors. Students' expectations, students' biases toward the instructor, students' attitudes toward the subject matter, the instructional environment, and many other elements can introduce error in these reports. Research reported by Andersen (1979), however, indicates strong correlations exist between student perceptions of instructor behavior and trained independent observers' perceptions. Thus, while there is error introduced when student perceptions of instructors' communication behaviors are taken as indications of actual instructor communication behaviors, there is evidence of the validity of those perceptions is at least as strong as perceptions of trained observers.

Perceptions of Instructor Credibility. Instructor communication behaviors are a causal element in their students' perceptions of the instructor's source credibility. If the student has been exposed, either in person or vicariously, to the instructor previous to the instruction, of course, their perception of the source credibility of the instructor may have already been established. This may introduce error in our theoretical model. Nevertheless, this theory suggests that the communication behaviors of the instructor will influence the students' perceptions of the source's credibility. 

An alternative to this theory is that the causal path will be from instructor choices of communication behaviors, to student perceptions of those communi-cation behaviors, to student perceptions of the instructor's credibility. This suggests, of course, that the perceptions of source credibility would be considered to be a third step in the theoretical process. Subsequent research is needed to determine which causal path is correct or whether there is more than one path in operation.

Step Three--Instructional Outcomes

Instructor communication behaviors are a causal element of instructional outcomes. The theory predicts that instructional communication behaviors will influence student evaluations of the teacher, their affective learning, and their cognitive learning. Once again, there are many factors which may have direct impact on instructional outcomes. These have been noted previously. Thus, it should not be expected that instructional communication behaviors can predict all of the variance in these outcome variables.

This theory predicts a direct impact of instructor communication behaviors on instructional outcomes. However, it may well be that this influence passes through students' perceptions of those behaviors and/or students' perceptions of the instructor's source credibility. Research is needed which tests these alternative causal paths.