Introduction

When serious moral questions are posed in the form of thought experiments, they lack the realness that we expect in our everyday lives. While thought experiments can shed some light on our moral decisions, virtual environments allow for a more immersive and realistic experience. However, previous experiments of descriptive ethics in virtual reality have lacked a sense of tangibility, thereby possibly reducing the level of immersion and potentially degrading the data. Our goal was to create an experiment that tests just how much power haptic feedback has when we’re making moral decisions.

In ethics, there exists a thought experiment called the “trolley problem,” originally outlined by British philosopher Philippa Foot (1967). Imagine you are in a train yard and you hear a runaway trolley coming down a nearby rail track. You look down the track and see that five people are stuck in the way of the trolley. They will die soon. Then, looking down, you see a lever that controls switch in the track. If you move the lever to its alternate position, the trolley will switch tracks. But, on this alternative track is one person who is also stuck. The question is posed: do you switch the lever to kill one person, but save five?

American philosopher Judith Jarvis Thomson offered a variant of the problem. Imagine that you are standing on a bridge. The trolley is still out of control, on its way to kill five people. However, this time there is a “fat man” in front of you who is large enough to stop the trolley. Do you push him off of the bridge?

Utilitarian guidelines, as outlined by Mill (1863) and others, would suggest pulling the lever or pushing the fat man, as one death is preferable to five. Indeed, previous studies have found that up to 90% of participants will choose to switch the lever (as summarized by Navarrete et al., 2012). On the other hand, a majority of subjects are disinclined to push the fat man (Singer, 2005), which may be tied to an emotional reaction against doing physical harm: while the lever case is abstracted away from murder, a push is much more physical.

As stated earlier, however, these problems are usually presented in non-immersive environments (e.g. text or conversation). Our aim is to present the “fat man” variant of the trolley problem to participants in our experiment. Whereas previous work has examined this problem in written surveys and even virtual environments (Navarrete et al., 2012), we have not found any experiments that employ haptic feedback. Since the world has haptic feedback, we expect experimental results closer to what we might expect in the real world.

To address the implausibility of the scenario and difficulties of moving into virtual reality, we created an isomorph of the trolley problem, a variant that keeps all relevant characteristics, but differs in appearance. We call this new scenario the elevator problem. In it, an elevator with four workers (first track) and another elevator with one worker (alternative track) are both suspended above an electrified floor (trolley). A participant sees the elevator with four people falling and can use two buttons (lever) to control which elevator is falling toward the floor. In our “fat man” version, we use a normally sized worker which the participant can push onto the electrified floor to save the four person falling elevator.