In the Sunday New York Times Magazine, "The Ethicist" fielded a query from a grad student who wondered about the practice of offering undergraduates extra credit to attend a conference hosted by their department. At the conference, "high-level" talks were presented; talks that most of the undergrads would be unlikely to understand.
The grad student thought that the undergrads were being exploited, as the main purpose of offering them extra credit was to increase the number of people in the audience, thereby perhaps convincing the university to increase funding for the conference in future years.
The grad student disapproved of this practice, and The Ethicist agreed, stating "You might as well fill the audience with potted plants."
Like many of you, I have given many talks attended by undergraduate students (and others) who did not have the necessary background to understand everything I presented. In some cases, these students were there by choice, and in some cases they were there for extra credit. Most typically, students lured by credit (extra or not) are undergrads, but I have also given lectures to audiences that consisted in part high school students who were required by their teacher to attend a Science Talk given by a Real Scientist.
Were these students potted plants? Perhaps some were, but many were not. The fact that at least some students are paying attention and trying to understand as much as they can is particularly obvious in settings in which questions are encouraged, even from non-experts. For students not comfortable asking a public question, there may also be opportunities for questions and other interaction after the talk. These can be very interesting discussions.
And even for those students who are unable to understand much of the content of a talk, there may be some value in attending a talk or a conference. In these settings, students get to see other academics in action, get a sense for the content and style of presentations, and observe how researchers interact with each other.
I encourage undergraduates who do research with me to attend conferences, including national conferences in our field. These students attend talks, many of which they don't understand, but they report being intrigued by the whole conference/cultural experience. I have also found that undergrads are quite adventurous about which talks they attend, sampling talks on topics that represent a wide range of sub-fields, to see what's going on, what's hot, who is interesting, who is not. Some of it is boring and much of it is puzzling, but it's also kind of fascinating.
I therefore disagree with the conclusion that undergrads who have insufficient background to understand high-level academic talks are passive potted plants, as many probably are getting something out of attending a talk or conference in their general field of interest.
Even so, to avoid the possibility of potted plant syndrome among extra credit-seeking undergrads being exploited by funding-hungry conference organizers, perhaps the experience could be enhanced somehow. Perhaps the students could be prepared in advance for some of the talk topics. Perhaps the students could meet some of the speakers after the talks for additional questions in a less formal, more undergrad-friendly environment. Perhaps speakers could be encouraged to spend the first couple minutes of each talk giving background information at a more basic level than they otherwise might. Perhaps everyone would find that more interesting.
I think the attending of talks and conferences by interested undergrads should be encouraged. I don't tend to give extra credit in my classes other than a 1-2 point fun/strange question at the end of exams, but, as long as extra credit isn't a significant portion of the grade, I don't have any problem with there being some sort of credit given for an academic experience that might well be enriching.