Imagine you’re standing on a footbridge over some trolley tracks. Below you, an out-of-control trolley is bearing down on five unaware individuals standing on the track. Standing next to you is a large man. You realize that the only way to prevent the five people from being killed by the trolley is to push the man off the bridge, into the path of the trolley. His body would stop the trolley, saving the lives of the five people further down the track.
What would you do? Would you push the man to save the others? Or would you stand by and watch five people die, knowing that you could have saved them? Regardless of which option you choose, you no doubt believe that it will reflect your deeply held personal convictions, not trifles such as your mood.
Well, think again. In a paper published in the March edition of the journal Cognition, a group of German researchers have shown that people’s mood can strongly influence how they respond to this hypothetical scenario. Though this general observation is well-known in the literature on moral judgments and decision making, the current paper helps to resolve a question which has long lurked in the background. That is, how does this happen? What is the mechanism through which moods influence our moral decisions?
Early research showed a difference between personal moral decisions, such as the footbridge problem above, and impersonal moral decisions, such as whether to keep money found in a lost wallet. Areas of the brain usually characterized as responsible for processing emotional information seemed to be more strongly engaged when making these personal as opposed to impersonal moral decisions, they found. These scientists concluded that emotions were playing a strong role in these personal moral judgments while the more calculating, reasoning part of our mind was taking a siesta.
Unfortunately, given the various shortcomings of previous investigations on this particular topic, there are a variety of other explanations for the observation that emotions, or the more general emotional states known as moods, affect how people may respond to the footbridge scenario.
For example, moods could influence the thought process itself. This is the “moral thought” hypothesis: just as something like attention may change our thought process by biasing how we perceive two choices, mood could also bias our thought process, resulting in different patterns of moral thinking. This is different from the “moral emotion” hypothesis, which suggests that emotions directly change how we feel about the moral choice. That is, our good mood could making us feel better (or worse) about potentially pushing, and therefore more (or less) likely to do it. Resolving this ambiguity with neuroimaging studies such as the one detailed above is difficult because of fMRI’s low temporal resolution – a brain scan is similar to taking a camera with the exposure set to a couple of seconds. This makes it difficult to faithfully capture events which happen quickly, such as whether moods change the experience of the decision, or if they directly influence the thought process.
To test these competing ideas, participants were first put into a specific mood by listening to music and write down an autobiographical memory. Those in the positive mood condition listened to Mozart’s Eine Kleine Nachtmusic and wrote down a positive memory, while those in the negative mood condition listened to Barber’s Adagio for Strings, Opus 11 and wrote down a negative memory. The participants in the neutral mood condition listened to Kraftwerk’s Pocket Calculator and wrote about a neutral memory.