I think the answer is yes, sometimes, but it depends on the emotion and it depends on the type of decision. A few years ago I did a research paper and experiment for a class, and my topic was the effects of mood on decision making in moral dilemmas. Positive mood seems to be able to influence certain moral dilemma decisions, so I tried a negative mood manipulation in my experiment. (It didn't do squat.)
An excerpt from the introduction part of my paper is below with references. I won't bore you with my own fruitless experiment that followed.
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Imagine being witness to a runaway trolley hurtling down the tracks toward five helpless people. Through the simple activation of a control switch, you have the power to alter the course of the trolley. Along the new path, only one individual is killed. Is flipping the switch the best choice? Now, consider a similar scenario: another runaway trolley is racing down a track toward five people. These individuals can be saved if you choose to push a large stranger off an overhead footbridge. The body of the stranger will block the runaway trolley’s path and save the five endangered individuals. Is it the best choice to push the stranger?
These two classic dilemmas, known as the trolley dilemma and the footbridge dilemma, respectively (Thomson, 1986), are tools that researchers have used to examine how people make moral decisions. Although the possible outcomes for either scenario are logically identical, people typically decide that flipping the switch is the right decision, while pushing the stranger is wrong (Greene, et al., 2001). In order to explain this phenomenon, behavioral and neuroimaging studies have been conducted to explore the underlying processes involved in these choices. The results have lent evidence that fundamentally different reasoning systems and brain areas are involved when solving the trolley and the footbridge dilemmas. Solving the trolley dilemma appears to be a logic-bound mental process, confined to higher reasoning and memory areas of the brain, while the footbridge dilemma engages an emotional circuit (Greene et al., 2004). A recent study has also shown that a positive mood can influence choices in moral dilemmas. Inducing a positive mood was found to increase the likelihood of choosing to push the stranger in the emotionally engaging footbridge dilemma but made no significant difference in the emotionally neutral trolley dilemma (Valdesolo and DeSteno, 2006).
Moral psychologists have historically adopted a rationalist stance when it comes to moral decision-making (Greene et al., 2004). The assumption is that mature human reasoning is a top-down process, ultimately overriding the speed bumps of emotional reactions to arrive at the most logically correct decision. More recently, investigators have begun to consider the impact of emotions in moral decisions. Social intuitionists argue that moral reasoning is a bottom-up process. The emotional reaction generates the decision first and the reasoning to justify it is constructed afterwards (Haidt, 2001). If emotion is at the root of decisions in moral dilemmas, then it is plausible that people can be influenced by a pre-existing mood as well as the emotional response evoked by the particular problem at hand.
The two possible outcomes that can be chosen for the trolley and footbridge dilemmas are classified as utilitarian or non-utilitarian. The utilitarian decision is the most logically correct choice with highest weight given to the most practical outcome. In this case, it is the sacrificing one life to spare five others. While the footbridge dilemma requires committing an emotion-evoking personal moral violation to arrive at the utilitarian choice, reaching the utilitarian response in the trolley dilemma involves a more abstracted level of personal involvement. This difference is described as "authoring" versus "editing" the outcome. The context of the utilitarian decision in the trolley scenario is threat-deflection, while the context of this same decision in footbridge dilemma is direct personal harm to another individual. Because of these different contextual levels of personal involvement, the trolley scenario is classified as an impersonal moral dilemma while the footbridge scenario is classified as a personal moral dilemma (Greene et al., 2004).
Neuroimaging reveals different patterns in brain activity for study participants resolving personal and impersonal dilemmas. Emotionally charged quandaries, such as the footbridge decision, have been shown to activate both reasoning and emotional centers in the brain, while the solving of impersonal moral dilemmas activates primarily reasoning and memory centers, but not the emotional areas (Greene et al., 2004). Similar brain patterns have been observed in study participants weighing decisions involving either pure reasoning or a personal stake in the outcome. At the neurological level, emotionally motivated reasoning and pure analytical reasoning appear to be qualitatively different processes (Westen, et al., 2006).
In a Northeastern University study on the effects of positive mood on moral decision making, Piercarlo Valdesolo and David DeSteno (2006) suggested that a competition arises between a person's emotionally intuitive and higher reasoning systems during the deliberation of a personal moral dilemma. This competition interferes with an individual’s ability to make the more logical, utilitarian choice. The immediate emotional response, triggered by the reprehensible nature of the act required, overrides the reasoning processes in the brain that are dedicated to computing the most logically correct outcome. The authors hypothesized that inducing a positive mood in a participant would quell the negative emotional feedback stemming from the personal moral dilemma (footbridge), and increase the likelihood of choosing the utilitarian outcome. Since the trolley dilemma was not shown to correspond with an increase in activity in emotion-related brain centers, they anticipated that there would be no significant difference in decisions between participants in positive or neutral emotional states. Before presenting the dilemmas, the researchers performed a positive mood manipulation by showing half the participants a 5-minute long comedy video clip (a Saturday Night Live skit). To establish a neutral (control) group, half the participants viewed a 5-minute long emotionally neutral documentary. All participants were then given the dilemmas, in random order, and assessed according to their responses.
After the presentation of each dilemma, participants were asked if the choice to kill one person to save five others was “appropriate” or “inappropriate.” Only one choice was allowed, with no measures in between, and a chi square analysis was performed on the data. Compared with the neutral mood group, the results showed that participants in the positive mood group, who had viewed the comedy clip, were significantly more likely to select the utilitarian ("appropriate") response in the footbridge dilemma. As predicted, responses to the trolley dilemma did not vary significantly between the neutral and positive mood groups.
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References:
Green, J.D., Nystrom, L.E., Engell, A.D., Darley, J.M., & Cohen, J.D. (2004). The neural bases of cognitive conflict and control in moral judgment. Neuron, 44, 390.
Green, J.D., Sommerville, R.B., Nystrom, L.E., Darley, J.M., & Cohen, J.D. (2001). An fMRI investigation of emotional engagement in moral judgment. Science, 293, 2105-2108.
Haidt, Jonathan (2001). The emotional dog and its rational tail: a social intuitionist approach to moral judgment. Psychological Review, 108(4), 814-834.
Thomson, J.J. (1986). Rights, Restitution, and Risk: Essays in Moral Theory. Cambridge, MA: Harvard University Press.
Valdesolo, P. & DeSteno, D. (2006). Manipulations of context shape moral judgment. Psychological Science, 17(6), 476-477.
Westen, D., Blagov, P.S., Harenski, K., Kilts, C., & Hamann, S.(2006). Neural Bases of Motivated Reasoning: An fMRI study of emotional constraints on partisan political judgment in the 2004 U.S. presidential election. Journal of Cognitive Neuroscience, 18, 1947-1958.