This semester, Dr. Nick Baker and our class looked at how our brains make sense of the world around us, how we perceive shapes, patterns, and sounds. During his presentation Dr. Baker explained how the brain automatically tries to understand a pattern or make sense of the whole image when looking at its parts. For class Dr. Baker had us read “The Role of Vertical Mirror Symmetry in Visual Shape Detection” by Machilsen et al. (2009) experiment, where participants were trying to make sense of random, striped dots called Gabor elements. When I read “The Role of Vertical Mirror Symmetry in Visual Shape Detection” I was shocked with the idea that our brains sometimes will ignore parts of the bigger picture and how our vision system has preferences that it adheres to when perceiving images such as symmetry. All this made me wonder, if the brain works so hard to organize and interpret visual information meaningfully, what happens when we apply that same process to something less objective like moral decisions? Also, are these judgments subjective to specific regions of the bain and can damage to a key brain region change what we feel is right or wrong just like it would change the way we perceive and image?
In 2022, van Honk et al. published a study in Proceedings of the National Academy of Sciences titled “Breakdown of utilitarian moral judgment after basolateral amygdala damage.” The researchers examined 21 patients with bilateral damage to the basolateral amygdala (BLA) and compared them to 42 healthy control participants. Each participant was presented with a set of moral dilemmas that required choosing between a utilitarian action, such as sacrificing one life to save many. Versus a deontological one, like refusing to harm even if it would save more lives. Participants also rated the permissibility of each action, providing both a yes/no decision and an evaluation based on a scale.
The results the study found was that individuals with BLA damage were significantly less likely to choose the utilitarian judgments where they sacrifice one for the health of a group than the healthy control participants. While most people wrestle with moral dilemmas such as the “trolley problem” and sometimes choose to sacrifice one for many, the amygdala-damaged group was far less willing to take that route.
The way this connects to Dr. Baker's talk steps in when both researchers introduced “noise” to distract participants from what might seem like black and white options. As Machilsen’s experiment introduced “noise” by misaligning dots, making it harder for participants to perceive shapes, van Honk’s experiment with amygdala damage introduces moral “noise.” In a healthy person, the BLA helps integrate emotional input with logical reasoning. So for someone like you, when you imagine harming someone, your amygdala generates that emotional gut feeling that makes such an action feel wrong. At the same time, your prefrontal cortex evaluates the logical consequences. In a typical brain these two inputs combine into a whole, similar to what Dr. Baker would call a Gestalt. But when the amygdala is damaged, the emotional input is excluded. The cognitive system still reasons, but the emotion that makes a decision feel whole is missing.
What makes this study especially interesting is that it flips a common assumption where we might expect that losing emotional input would make people more willing to make logical trade-offs. Instead, van Honk et al. found the opposite with participants becoming less utilitarian in their choices. Without the emotional input from the amygdala, those participants were unable to endorse harming one person, even if it would save many others. Showing their moral decisions as fragmented because they could not fully process or accept the trade-off of lives in the dilemma, and their decisions ended up relying only on detached sense of reasoning that choosing to kill anyone is wrong.
The study shows that the amygdala acts as a bridge between emotion and logic. It gives our minds the ability to consider both the emotions and logistics of moral dilemmas making it possible for utilitarian reasoning to feel acceptable. Without this connection, people can still think through the logic, but the final step of feeling the decision as emotionally right or wrong never happens. This is similar to how symmetry recognition in Machilsen’s experiment suddenly makes a random pattern click into place in the context of seeing the whole picture.
This indicates to us that maybe similar to how the visual system uses symmetry to make sense of scattered fragments in images, the moral system uses emotions to bring structure and meaning to facts and outcomes. When the visual system is disrupted, shapes remain hidden in noise. On a similar note, when the emotional system is disrupted, the overall moral problem becomes incomplete.
This research also raises questions about recovery and neuroplasticity. We learned that with our vision, the brain can reorganize and learn new strategies to detect patterns after disruption. Could the same be true for morality? If patients with amygdala damage can retrain other regions to compensate?
References
Machilsen, Bart et al. “The role of vertical mirror symmetry in visual shape detection.” Journal of Vision vol. 9,12 (2009): 11.1-11.18. Doi: 10.1167/9.12.11
van Honk, Jack et al. “Breakdown of utilitarian moral judgement after basolateral amygdala damage.” Proceedings of the National Academy of Sciences of the United States of America vol. 119,31 (2022): e2119072119. Doi 10.1073/pnas.2119072119
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