I have discovered that many scientists don’t practice their talks. Science may be the only profession where folks regularly stand up in front of a big group of people and discuss their work without having first practiced their presentation. This doesn’t make any sense to me. The members of your audience decided to take valuable time out of their day to come hear you speak. If there are a hundred people in the room, then they have invested a hundred people-hours to listen to you. Isn’t it worth a few hours of your time to practice your talk? Why would you waste their time with a talk that doesn’t get to the point or that does not clearly communicate the central message of your work? I have no idea where this culture of throwing together slides and “winging it” came from, but it is pretty obvious which science talks have been practiced and which have not.
People with different levels of experience should use practice time for different reasons. For young scientists, it is useful beyond measure to practice your talk in front of other people. Choose the audience for your practice talks carefully. Don’t invite too many people. A large audience can result in lots of advice, perhaps too much, and it can be difficult to parse out the useful suggestions from the gratuitous comments. Usually it is best to have just a few people who work in your area and a few from outside your area. I have found it useful to have an audience with a mix of experience, like one or two senior colleagues together with a few junior colleagues. In general, junior colleagues often help to identify points that aren’t clear in the talk, while senior colleagues often help to reorganize the talk or rephrase parts that are not clear, though some people are great at both!
There are many good reasons to practice in front of an audience. Obviously, this practice audience will give you feedback on how to improve the talk. Less obviously, you can tell during the practice talk what is working and what is not. Make sure you actually look at people in the audience while you practice. For one thing, this helps you learn how to talk to the audience like you are talking to people. In addition, you can often gauge from people’s facial expressions whether they are getting what you are saying or not and whether they are bored or engaged. Many people recommend video-recording your talk so that you can watch yourself give the talk, to learn what works and what doesn’t. I am sure this can be helpful, but I should emphasize that I am not interested in turning scientists into actors. I just want them to communicate their science clearly. Talks need not be super-smooth, elegant productions. I just want scientists to explain what they have discovered in clear, plain language.
I think the importance of practicing is already appreciated by the younger generation and it is now common practice for young scientists to practice their talks. I think what is less well appreciated is the fact that it is most useful to practice early and practice often. Practicing early gives you the opportunity to seriously rework a talk, should that be necessary. Often, it is not entirely clear what is wrong with a talk and it can take a few days or a few weeks to find a better way to tell your story. If you practice only a few days before your presentation, then you have foresworn the opportunity to seriously revise your talk.
Practicing often provides many benefits. I practice my talks. Then I practice again. Then I practice some more. For new talks, I usually practice at least three times. One reason I practice so much is that I try very hard to avoid jargon in my talks. I don’t always succeed at killing all the jargon, but that is my goal. Explaining complex science in plain language is just plain hard! It takes practice to find plain language that is both accurate and concise to explain your science. I find that this effort is paid back tenfold by the fact that most of the audience seems to understand my talks, which I know because many people ask sophisticated questions about the work.
As you become more experienced in giving talks, you can reduce the ratio of practice talks in front of people to practice talks on your own. Sometimes I practice in front of the folks in my lab, but usually I just practice in an empty room. Practice talks in front of people, and in front of cameras, are great ways to learn to avoid the worst habits (like talking to the floor). I learned to avoid these bad habits long ago and I no longer practice to improve my performance or to appear “smooth” in my presentation. Instead, I practice to hear the flow of the story.
What do I mean by this? For one thing, words spoken out loud can sound different from words written on a page. So, sometimes, the logic of your scientific paper will not convert nicely into a story for a talk. Second, papers often contain more details than are required to communicate the core ideas of your work. I always strongly recommend that folks cut most of the supporting information from their talks and focus on presenting the critical data and experiments that support their conclusions. Remember that your audience will absorb and remember far less information from your talk than you carry in your head. If you can communicate one or two really critical ideas, then you will have succeeded. Everything in your talk should be in the service of communicating those critical ideas. Scientists routinely over-estimate what members of the audience know and understand, causing many presenters to take shortcuts through the material. Presenting complex work to a live audience should not be the first time that you have tried to explain this complexity with words. If you practice, and practice again, you are more likely to find a flow of words that communicates the big messages of your talk without getting stuck in the weeds.