Plagiarism?

There was an article in Inside HigherEd today discussing the cultural difficulties in defining plagiarism. We have had this conversation here as well about working with students from other cultures. When you have international students attending college in the United States how explicit are we when the penalties for plagiarism are explained? I know from my own experiences teaching a graduate course that I assume much about my students' understanding of what plagiarism looks like. We in the library are also struggling with our faculty's assumptions about their students' understanding of plagiarism. Many departments, rather than holding a discussion about plagiarism, use plagiarism detection software like turnitin.com. So is it more effective to use the stick rather than the carrot approach? I personally feel that if we are starting from the position that we assume our students will plagiarize and want to punish the offenders that we have no where to go. We need to explore why plagiarism is given such little attention in higher education when our consequences for committing plagiarism are so devastating.