First, the students were asked to come up with their own dilemmas. Here is an example:
Alice is taking her daily walk along the train tracks when she notices that the approaching train is out of control. Alice sees what has happened: the driver of the train saw a toddler playing in the tracks and slammed on the brakes, but the brakes failed and the driver fainted. The train is now rushing toward the toddler, and it is moving so fast that he will not be able to get off the track in time. Fortunately, Alice is standing next to a switch that she can throw that will turn the train onto a side track, thereby preventing it from killing the toddler. Unfortunately, there is an adult man on the side track. Alice can throw the switch and kill the man, or refrain from doing so and let the toddler die. Is it permissible for Alice to throw the switch?
The basic question, of course, is whether people take age into consideration when making moral judgments in trolley problems.
Then, the students collected thousands of responses to this and other questions. Here are some of the results for age. This shows how permissible it is to kill an adult, in order to save (1) a toddler, (2) another adult, or (3) an elderly person. (PDF)
These results show that people think it is more acceptable to kill an adult to save a toddler, than to save an adult or an elderly person.
