Symposiums are serious events, where people discuss serious issues. That said, an interesting trend that is catching up is the one where artists are invited to perform during the symposiums, especially during the transitions from session to session. This is indeed something you should consider adopting, if you are involved in planning of a symposium. If you can get good artists to perform during your symposium, especially during the transition from one session to another, they may be in a position to give the symposium attendees the breaks they need, as they try to reorient their minds.
Of course, the artists who are engaged to perform at symposiums need to be the sorts of artists whom the symposium attendees are likely to find interesting. So you need to look at the expected attendees, and try to understand the sorts of artists they would be likely to find interesting. Then you should (only) engage such artists.
You need to hold discussions with the artists who are engaged to perform during symposiums – discussions where you can touch on various matters to do with their performances. In other words, you shouldn’t leave it to the artists’ discretion. You need to have discussions on the sorts of performances they are to do during the symposium session transitions, how long the performances are to be, and what the cues for them to start (and stop) performing are to be.
To avoid bad publicity, you have to ensure that the artists who are engaged to perform during symposiums are promptly paid for their services. They also need to be well-paid. Sometimes, one is tempted to use something like the Walmartone paystub scale, to figure out what is to be paid to the artists: because their contribution seems to be so small. But when all is said and done, you have to appreciate that the artists are professionals, just like the speakers/resource-persons and other facilitators in the symposium. So they have to be paid decently, also keeping in mind that it takes a lot of practice, for them to be able to deliver their flawless performances.