In cognitive neuroscience, plasticity pertains to the ability of neurons to change their composition and behaviors relative to the information they process and the person’s experiences. As we interact with the world our neurons change to help us understand how to respond to various situations we encounter. Two parts of the brain closely connected to plasticity are the amygdala and the hippocampus. I describe more about these a bit later in this section.
Neurobiologists recognize, much as humanities scholars such as Gee, Pinker, and Mayer, that experience plays a role in learning about information and values. What one understands of a given bit of information and how they tend to best learn information affects how they learn new information. Berlucchi and Buchtel (2009) define neural plasticity as:
changes in neural organization which may account for various forms of behavioral modifiability, either short-lasting or enduring, including maturation, adaptation to a mutable environment, specific and unspecific kinds of learning, and compensatory adjustments in response to functional losses from aging or brain damage. (p. 307)
Studies related to plasticity tend to examine how one responds to a series of subsequent experiences of certain modal combinations after first exposure, especially related to cognitive development. Generally, the brain is able to process information more quickly as it learns more about that information. Depending on the amount of exposure to information and the way the information is provided, cognition about the information can occur more quickly.
Because plasticity is affected by social interaction over time, culture also impacts persuasive rhetoric; a particular message may have a better persuasive effect in one culture but not another merely because of social expectations and perceptions of rewards or attributes of the product itself. There is a special connection between culture and persuasion because of how our brain responds to cultural influences, but some of our responses are simply natural.
The hippocampus is a place in the brain that helps us store information about our experiences. How was the experience? How did we react? Was our reaction appropriate and did we benefit from our reaction? If not, how can we change our reaction so when we experience it again we know to respond that same way? This is culturally determined through social interactions. As a young child, when I respond to a new event or experience and receive positive feedback from my parents or others whose feedback I value, I learn that my response was appropriate. Over time, then, I learn to respond that way in similar situations.
Likewise, our basic desire for self-preservation impacts our responses to people or events that we do not understand or that we did not like; such people and events invoke fear in us, persuading us against doing them in the future. The amygdala is part of the neurological system in the brain that concerns these basic desires. We are born with the desire to stay alive, and the amygdala helps us do that by sending signals to the brain when we encounter something new that may be dangerous to us. Young children—less than 4 years old, for example—often cry when a stranger speaks to them, and they clutch a parent’s leg or torso. This is a reaction to the fear of this new experience. The child does not know who the new person is and responds with fear, grabbing what it knows will protect it. Plasticity is part of this dynamic because we experience events that affected us negatively, and we try to avoid them in the future. Over time, our neurons have associated that event or person with fear.
Another area of plasticity study is the effect of brain injuries or disorders on cognition. Some scholarship in rhetoric theorizes relative to such disorders and injuries. For example, there is some study in the fields of rhetoric and cognitive psychology about how to facilitate learning among those with autism. However, less study in how such disorders affect persuasion exists.
Because of this body of literature that overlaps much of what has been done in multimodal rhetoric scholarship and the growing interest in interdisciplinary study, it is important for disciplines to find ways to synthesize their work. The disciplinary divide related to discourse differences discourages such interdisciplinarity, and scholars in both areas recognize how this negatively impacts the study of cognition. However, this text attempts to build a bridge by which rhetoric and social science scholars can contribute to biomedical cognitive neuroscientists; and, consequently recognize the value of rhetoric scholarship in STEM programs and vice versa. I outline the remainder of the book in the following section.