Last month I wrote about how the "reality" which we think of as existing universally around all of us, is actually a reality created in each of our minds independently. Because there is enough overlap between our respective realities, most of us are able to interact with others and function within our shared society in a way that makes us forget that our realities are not identical. Our brains operate, similar to three-dimensional printers, by interpreting data from the outside world to build a picture of that world inside our brains. This picture of the world that exists in our brain is far from an exact replica of the outside world. Moreover, because each of our individual 3D-printers recognizes different data and codes different criteria into the process, our inexact replicas of the world are different from the inexact replicas being created simultaneously by those around us. The result is that we create then experience different realities, every day, all day long.

Although certainly not ideal for a system premised on the idea that we can put two people under oath and make credibility determinations about them when their accounts of an event do not align, the "different realities" problem is not the whole problem. While I am admittedly a self-taught pseudo-neuroscientist, the information about our brains which in my opinion drives a stake into the heart of the legal system, is what David Eagleman describes as the "internal model."

The internal model is a prefabricated model of the world around us, which we form by predicting what the data which will be captured by our senses will reveal. This prediction is based on an individual's genetics and prior experiences, which combine to formulate that person's expectations. Most sensory information is sent from our data receptors to the thalamus, and the thalamus sends relevant information to the appropriate region of the cortex. For instance, with respect to vision, visual information travels first to the thalamus prior to its transmission to the visual cortex. Importantly, however, for each transmission of information from the thalamus into the visual cortex, ten times as much information travels in the opposite direction. "Detailed expectations about the world - in other words, what the brain 'guesses' will be out there - are being transmitted by the visual cortex to the thalamus." The thalamus compares all of the data it receives before transmitting to the visual cortex only the data which represents prediction "errors" - the difference "between what the eyes are reporting, and what the brain's internal model has predicted." When we encounter "errors" in matters that we deem relevant to our lives, our internal models change and we learn. As we age, our brains tend to learn less and predict more.

Therefore, we all utilize "default" prefabrications of reality, formed from our own unique prior experiences, which can directly contradict the objective reality of the outside world. If internal models only change when these contradictions are relevant to our own lives and situations, there is necessarily a tremendous amount of error perpetuated in our internal models which may never be corrected. It seems reasonable to assume that these skewed internal models impact every facet of the judicial system. We learn by creating associations, and our brains incorporate these associations into our internal models. If certain associations are strengthened by repetition or relevance, it may be difficult to recognize "errors" and challenge those associations. Problematically, these unchecked prediction errors persist and continue to distort our internal models.

While it is likely that those who drafted the U.S. Constitution knew less than even I do about neural associations and internal models, the Sixth Amendment entitlement to an "impartial jury" seems like a protection well-suited to combat the effects of our skewed internal models and lack of shared "realities." Historically, some courts have encouraged the selection of diverse juries as a way of satisfying the requirement of an impartial jury, finding that diversity improves the quality of deliberation and reduces the risk of bias. More diversity among jurors reduces the likelihood that a jury verdict will be based on a preexisting association error which lurks, undetected, in the internal models of those evaluating evidence.

Unfortunately, since 1986, when the Supreme Court decided Batson v. Kentucky, the use and regulation of peremptory challenges in the process of selecting a jury have operated as a roadblock to diversity. Next month, we will put peremptory challenges under the "macroscope."