Neurotransmitters and Moral Decision-Making

Neurotransmitters and Moral Decision-Making

In Joe Vukov’s talk about neuromodulators and how they affect decision-making he explained to us the underlying importance that neurotransmitters, such as serotonin, have in human behavior. He analyzed Molly J. Crockett’s article, “Neurochemical Modulation of Moral Judgment and Behavior,” in which she studied the effects of different levels of serotonin on moral judgment and decision-making. She aimed to answer how brain chemistry affects morality. In the first part of her study she tested how lower and higher levels of serotonin affect a person’s moral permissibility of harmful actions. Participants were given either citalopram, atomoxetine, or a placebo pill on three different occasions. Citalopram acts by blocking the reuptake of serotonin, thus allowing for serotonin to act on postsynaptic receptors longer. Atomoxetine, which is a noradrenaline reuptake inhibitor, blocks the reuptake of noradrenaline increasing the amount of noradrenaline at synapses. Participants were given three different types of scenarios: “neutral scenarios that contained no moral content, ‘personal’ moral scenarios in which harmful actions were emotionally salient, and ‘impersonal’ moral scenarios in which harmful actions were not emotionally salient” (Crockett 238). She found that neutral scenarios and impersonal scenarios showed no differences across the three administered drugs. However, for personal scenarios, when citalopram was administered, participants were more harm averse. Suggesting that increased levels of serotonin promote more deontological decisions.

            In the second part of her investigation, she tested how varying levels of serotonin affected costly punishment behavior. To do this Crockett used the ultimatum game and acute tryptophan depletion to compare responses of participants with higher levels of serotonin available and those with lower serotonin available in the brain. By lowering the amount of serotonin available, participants rejected unfair offers more, while those who had enhanced serotonin function due to citalopram, rejected unfair offers less. Atomoxetine exhibited no effect on decision-making. Putting together all of Crockett’s findings it is hard to pinpoint just how serotonin modulates morality. It is not totally dependent on serotonin, but it shines light on what future directions we should take in evaluating moral decisions.

            In another article, I found that in “The impacts of Val58Met in Catechol-O-methyltransferase (COMT) gene on moral permissibility and empathic concern,” the researchers explore how COMT Val158Met is associated with emotional processes in decision making. The catechol-O-methyltransferase (COMT) gene is known to modulate the levels of dopamine. The COMT enzyme “degrades dopamine in the prefrontal cortex,” which is encoded by the COMT gene (pg. 53). Associated with this gene is a functional polymorphism in Val158Met which leads to a substitution of valine for methionine resulting in Met/Met genotype exhibiting 40% less enzymatic activity than the Val/Val genotype (pg. 53). Thus, the researchers predicted that those with the Val/Val genotype, which corresponds to lower levels of dopamine would exhibit more empathy than the Met/Met genotype, which corresponds to higher levels of dopamine. To test this the researchers recruited college students and divided them into groups based on whether they had this polymorphism. The researchers conducted an assessment that dealt with moral permissibility. In the moral permissibility assessment, participants were given 16 hypothetical moral dilemmas in which eight were personal and eight were impersonal. Participants were then asked to rate from 1-7 whether it was morally permissible.

The researcher found that in the moral judgement test, COMT Val158Met can predict differences in moral permissibility in impersonal dilemmas. Those with the Val/Val genotype recorded lower permissibility on impersonal scenarios and exhibited higher empathic concern than the participants with the Met/Met genotype. They found that the Met/Met genotype increases participants moral permissibility. Thus, suggesting that increased levels of dopamine reduce individuals empathic concern. Overall, this study highlights that different levels of dopamine contribute to our moral judgement. This article is like Crockett’s investigation because both studies evaluate how neurotransmitters affect one’s moral judgment. Crockett studied how varying levels of serotonin can affect morality while this one evaluated the different genotypes of COMT Val158Met, which correspond to different levels of dopamine. Both these articles highlight how important neurotransmitters are in higher cognitive decisions, shining light on how much there is to learn about the role of these neuromodulators in decision-making and moral judgment.

Works Cited

Crockett, Molly J. “Morphing Morals.” Moral Brains, 2016, pp. 237–245.,

doi:10.1093/acprof:oso/9780199357666.003.0011.

Ru et al., 2017 W. Ru, P. Fang, B. Wang, X. Yang, M. Xue, P. Gong The impacts of Val158Met

in Catechol-O-methyltransferase (COMT) gene on moral permissibility and empathic

concern Personal. Individ. Differ., 106 (2017), pp. 52-56.