One of my professors (who shall remain nameless for his own protection) told me this story about a doctoral student who was doing research at a hospital for the seriously mentally ill. My professor was curious and wanted to observe the study at the hospital. The experiment took place in the basement of the hospital. The doc student had built a contraption that shot out an M&M to the study participant (hospital resident) whenever they uttered a word or sound. The goal was to see if this promoted verbalization among the client population (apparently, a problem).
My professor is a sociologist so he asked to tour the facility. He noticed that the staff seemed tired and frustrated - and so did the residents. He approached a staff member who seemed very happy to converse with a non-resident. During their conversation, he noticed residents approached the staff member to ask for things. The staff member responded by, essentially, shooing them away and reprimanding them for interrupting. My professor thought it ironic that in the basement an experiment was going on to promote vocalization among residents while on the third floor of the hospital, verbal requests were shunned and spurned.
After talking to students in class about the power of using their voice, I would often "reward" their emerging efforts to do so by shooting them imaginary M&Ms in class. At our termination retreat brunch, I bought tons of M&Ms in many flavors. They deserved every single one.