Bias and decision making

Where Bias Reigns

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To Bias is Human

When we think about bias, we tend to think only about the prejudicial biases that favor one perspective, group, or person, over another in a way that is harmful or unfair. We believe that bias is a net negative, something to fight against and avoid at all costs. With prejudicial biases that lead to injustice and inequities this is certainly the case. What is often missed in these discussions, however, is that bias, at its root, is fundamental to decision-making. It is an indissoluble aspect of survival. We can no more remove bias from decision-making than we can remove breathing from human life. The ability to bias information and make decisions is hard-coded into our neurobiology. There are designated neural and endocrine pathways within the brain and body that form a biasing network of sorts whose sole purpose is to tag incoming information with emotion so that we can ‘decide’. The biasing network involves communication tracts between nuclei in what are called the ventral and dorsal medial prefrontal cortices (a region in the very front of the brain, above the nasal cavity, behind the eye socket), the insula (a region deep in the center of the brain) and the amygdala (on both sides of the brain, roughly behind the ears) and to and from the body.

Individuals with injuries directly to these regions and/or that sever the communication tracts, have impaired decision-making precisely because they cannot bias information. They operate on what might be viewed as an excess of rationality, in a state of emotionless ‘objectivity’, weighing the pros/cons of everything, only to finally act in what looks like an entirely impulsive manner. And it is. Without the physiological biasing systems, no amount of factual data can sway a decision. To a person with this particular type of injury, it is as if there are equal pros and cons and so one might as well flip a coin. Researchers who study these injuries explain the impulsivity not as an emotional response, but as it’s opposite. The patients lack the brain and/or brain-body connections that inform what we normally attribute to unconscious, ‘emotional’ or psychological biases. Let us look at one such case more closely.

When Bias Fails

Elliot (a pseudonym) was a healthy thirty something young man who developed a meningioma in the prefrontal region of his brain. A meningioma is a type of brain tumor that develops in the brain’s outer covering, the meninges. Prior to brain tumor, he was described as highly intelligent, hard-working, and socially engaging. He was good husband, a father and had a successful career. As the tumor was developing, he developed headaches. Along with the headaches, family and friends noticed that his personality began to change and that he seemed to lose his sense of ‘responsibility.’ By the time the tumor was identified and removed, it had grown to the size of an orange, compressing a fair amount of the surrounding brain tissue.

By all accounts the surgery was successful. Elliot had seemingly had regained all of his physical and intellectual capacities, but somehow, despite having superior intellectual capacity, and the appearance of being healthy, Elliot could not function. In an excerpt from his book, Descartes Error, Antonio Damasio, the neurologist who developed the body of research delineating the neural biasing system, describes Elliot:

 “The patient had undergone a radical change in personality, I was told, and the referring physicians had a special request: they wanted to know whether this change so at odds with previous behavior was real. Elliot, as I will refer to the patient, was then in his thirties. No longer capable of holding a job, he was living in the custody of sibling…For all the world to see, Elliot was an intelligent, skilled and able-bodied man who ought to come to his senses and return to work. Several physicians had decided that his mental faculties were intact – meaning that at the very best Elliot was lazy, and at the worst, a malingerer.

I saw Elliot at once, and he struck me as pleasant and intriguing, thoroughly charming, but emotionally contained… He was cool, detached, unperturbed even by a potentially embarrassing discussion of personal events…

Not only was Elliot coherent and smart, but clearly he knew what was occurring in the world around him… He had a flawless memory for his life story, including the most recent, strange events…

[Prior to the tumor] Elliot had been a good husband and father, had a job with a business firm, and had been a role model for his younger siblings and colleagues. He had attained enviable personal, professional and social status. But his life began to unravel. He developed severe headaches, and soon it was hard for him to concentrate. As his condition worsened, he seemed to lose his sense of responsibility and his work had to be corrected by others…

… An excellent medical team performed the surgery, and the tumor was removed. As is usual in such cases, frontal lobe tissue that had been damaged by the tumor had to be removed too. The surgery was a success in every respect, and insofar as such tumors tend not grow again, the outlook was excellent. What proved to be less felicitous was the turn of Elliot’s personality. The changes, which began during his physical recovery, astonished family and friends. Elliot’s smarts and ability to move about and use language were unscathed. In many ways, however, Elliot was not Elliot.

Consider the beginning of his day: He needed prompting to get started in the morning and prepare to go to work. Once at work he was unable to manage his time properly; he could not be trusted with a schedule. When the job called for interrupting an activity and turning to another, he might persist nonetheless, seemingly losing site of his main goal. Or he might interrupt the activity he had engaged, to turn to something he found more captivating at that particular moment…

… His knowledge base seemed to survive… But he could not be counted on to perform an appropriate action when it was expected… Elliot’s job was terminated. Other jobs — and other dismissals were to follow.

… No longer tied to regular employment, Elliot charged ahead with new past times and [risky] business ventures… Several warnings from friends were to no avail and the scheme ended in bankruptcy…

His wife, children and friends could not understand why a knowledgeable person, who was properly forewarned, could act so foolishly, and some of them could not cope with the state of affairs. There was first a divorce. Then a brief marriage to a woman of whom neither friends nor family approved. Then another divorce. Then more drifting…

… The tragedy of this otherwise healthy and intelligent man was that he was neither stupid nor ignorant, and yet he acted often as if he were. The machinery for his decision-making was so flawed that he could no longer be an effective social being…”

For those of us schooled in the Western tradition, where objectivity and rationality are prized all else, the notion that rational decision-making is somehow predicated on emotion, is a radical one; one that if we uphold, would lead to us to ignore Elliot’s unique constellation of symptoms and attribute them to malingering, the technical term for faking it. Many physicians before Damasio had done just that. They surmised that because his intellectual capacity remained intact, his erratic behavior was nothing more than attempt for attention, that he was somehow faking it and that, ironically, ‘it was all in head’. And indeed, it was, only not in the manner anyone suspected.

How We Know

From the biological standpoint, we see that how we ‘know’ what we think we know, has as much to do with functional neurobiology as it does about intellectual capacity. Damasio’s work calls into question not only the how we judge neurological health and fitness, but also, the entire western paradigm that objective decisions exist. While Damasio and his colleagues focused on anatomical injuries to specific regions of the brain that removed emotion from the decision-making equation, one could easily surmise how perturbations in the chemistry within these tracts might also affect one’s biasing system, turning up or down the signals sent and received, up- and down- regulating the emotionality and the learning that comes from these emotional tags to situations. Similarly, it is also possible that chemistry changes within the body and in the tracts that manage and communicate these autonomic and body state signals, might fundamentally alter decision-making capacity. Considering the toxic chemical and chronic illness burden of modern man, it is fair to question whether our capacity to make decisions is not impaired, or at least fundamentally altered, in a manner similar, though perhaps not as drastically, to Elliot’s. In other words, are we more similar to Elliot than we think?

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Article published originally on November 5, 2019. 


Chandler Marrs MS, MA, PhD spent the last dozen years in women’s health research with a focus on steroid neuroendocrinology and mental health. She has published and presented several articles on her findings. As a graduate student, she founded and directed the UNLV Maternal Health Lab, mentoring dozens of students while directing clinical and Internet-based research. Post graduate, she continued at UNLV as an adjunct faculty member, teaching advanced undergraduate psychopharmacology and health psychology (stress endocrinology). Dr. Marrs received her BA in philosophy from the University of Redlands; MS in Clinical Psychology from California Lutheran University; and, MA and PhD in Experimental Psychology/ Neuroendocrinology from the University of Nevada, Las Vegas.

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