[academic filter] know nothing, must give comment on it, on the fly. how to be OK with this?

Do you know the names of the presenters and the titles of their papers? How long should your commentary on each be? Basically, the way to get through this is to realize that the audience knows you are not Dr Famous. The audience knows you are a junior person. You are just fine, and they've all been through it, and in any case you won't be onstage for very long. You will do a bit of homework on each of the presenters ahead of time, and come up with two nice points to make about each presenter's work in general. Those will be your fallback points. They don't have to be great. During the talks you will be looking for two nice points per talk. These can be positive (what a good insight) or inquisitive (I wonder if you would get the same results if you ran the study with x method instead), they need not be critical. And, key technique often used by hack older researchers to cover up when they don't know jack about a talk topic: you can talk about how these things relate to your area. This is not a great plan A, but it's very common and a fine plan B if you are really feeling out of your depth. You can even say "Dr Famous wasn't able to be with us today, so instead I'm going to address these talks from the perspective of someone in $my-area."

It's over now. Blathered incoherently for ten minutes, I was absolutely petrified and messed up the order of my points. Thanks to everyone for all the good advice - I did manage to bring the conversation around to my own area somewhat, and hopefully did so in a not too obvious way. I know everyone understood that I was just stepping in for someone at the eleventh hour which may have helped, and people did tell me afterward that they liked my comments but they were probably just saying that to make me feel better, or were obliged to because they were the conference chair who dragged me in at the last minute... Something which helped me, and which may or may not help anyone else, was that I took off my glasses while giving the talk, which meant I could make eye contact with people without really seeing their expression, or whether they were looking at me or not, which helped with enforcing blissful ignorance of their judgment or skepticism or disagreement.

The further along I got in my career the more clear it became that the experts don't know everything-- shocker, I know. I'm in my mid 40s and have seen my career from two perspectives now: the pleb and the senior researcher...and I can tell you that there is nothing more refreshing than seeing the junior researchers get up and present at a conference. You will be engaging no matter how badly you screw up (which you won't). The junior researchers know often know a broader range of topics, while senior people get so focused that most can barely have a conversation outside of their specific area. This is such a fantastic opportunity for you, whether you hit every sentence spot on or fumble through it, it's a win win situation for you.

Lots of good advice here already so I won't repeat what's already been said, but I would like to focus onvery roughly in my field of research but not enough that I'm all that comfortable with it.I'm a postdoc, and have switched fields twice during my short career. And I've found that, to an extent, you can turn "not-quite-my-field" into an advantage. That is: don't feel that you have to say what Dr Famous would have said. Make whatever connections you can between the content and the things you know well, and come at it from that angle. Remember, they're asking for your comments so it's perfectly OK to give them from your not-central-to-the-field perspective. This puts you at a great advantage: you're now talking about a topic, or at least a perspective, which you know better than most or all of your audience. This means it's hard for them to ask awkward questions, and they will probably be at least somewhat impressed -- you might be repeating things which are commonplace in your field, but to them it will be new! (As for the "got my job by accident, shouldn't be here" feeling: maybe not everyone gets that, but I'd wager that most of us do. I do. There was an Ask about it within the last week or so, so search for that if you want reassurance that it's a Perfectly Normal Thing.)

First, is there any chance you can get in touch with the original commentator, even briefly, to get ideas on some talking points? If you can, do so immediately-- it could be a good, rough outline to start. Second, you mention that you feel that you don't have a good grasp of the field-- given the time constraint, can you pick a few papers that would make you feel more empowered in your role tomorrow? I'm not in academia, but I have done many a moot court competition and appellate advocacy exercises. That said, a few tried and true tips for calming down the nerves. Psych yourself up. Try hard not to let your insecurities get the best of you. Deep breaths. I know I have a tendency to talk quickly when I'm nervous. Pace yourself. Silence is okay. Don't worry about what you THINK people expect. Consider yourself a rock star given the circumstances-- filling in last minute is NO small task.

lollusc's suggestion is very good. Write down in advance what parts of your own field you can possibly relate back to, and prepare what to say once you get there. If you have a few of these prepared pieces, all you need to do in the heat of the moment is find the hooks that allow you to fit them into the discussion at hand. You can also think of some formulations that will bring you to your home turf without seeming like abrupt changes of subject. Another thing is that you won't dive in on the content the very first thing you do. You are going to start along the lines of "First of all, I find Dr A's take on this very interesting, it certainly brings a new perspective on the work of B, and I look forward to hearing Dr C's comments on this in the context of D..." I don't know what a suitable opening sentence would be for you and your field, but whatever it is, formulate something ahead of time and rehearse it! If you don't hesitate or stumble for those first ten seconds, you will give an impression of confidence and sharpness. It also gives your brain some time to digest what the previous speaker just said, and makes it easier for you to keep talking with a good flow. Good luck!

First, you're a postdoc in a related field. You earned that education and I assure you that you know more than you're giving yourself credit for knowing. I have zero experience with academia (outside of being a student), so this advice may not be worth much, but my general approach would be one of: * Figure out how the topic relates to what you do, and then JUST TALK ABOUT WHAT YOU DO. This would require some thinking on your feet, but if the connection is reasonable at all, you know what you're talking about (and you do), and you sound confident, my guess is that no one will question you. Think about Presidential debates. They'll go completely off on a tangent, and much of the time you don't even notice that they didn't answer the original question. No one really points that out. In short, answer the question you wish you were asked. * Be honest with your audience and say flat out that you were approached at the last minute, you have an educated familiarity (is that a thing?) with the topic and simply approach it that way. How do these papers play to an audience with some familiarity (but no specific domain expertise) of that topic? There's your comment. * Learn ONE THING related to the subject as well as possible in the time you have left and then find a way to say that one thing. Otherwise keep your comments to a minimum. * Can you ask the original panelist for her notes or observations on the topic (if she has any) and then credit her for writing them? Good luck!

Really, just remind yourself that everyone knows: -I am filling-in for Dr Famous, and this is not my area. -They did not circulate the papers beforehand. So you have nothing to lose. They aren't judging your competence in your area, and they aren't judging how well you have prepared, because there was no way you could have prepared. If you say something surprisingly insightful, bonus. If you say something that's only baseline "what an intelligent person would say", rather than brilliant, it is fine. Discussion will focus on the papers, not on your commentary, and that will be fine.

I read the thread the other night with great interest, and I just thought ooh, I gotta go back and see how it all turned out. Well I'm glad you reported back and that you made it through alive. That was a tough situation you found yourself in and you did a brave thing. I'm sure I speak for everyone here when I say we're proud of you. I was pullin' for ya!