Neuroscience is finally starting to crack the twin processes of remembering and forgetting – with important implications for public speakers.

Important because, as I’ve talked about before, audiences forget more than they remember – a whole lot more – and the process of public speaking is a poor way to present information. At least, information that you want your audience to remember. The numbers vary from one study to another, but audiences forget anywhere from 70 to 90 percent of what they hear in a typical speech.

Those are terrible odds, if you’re a speaker hoping that your audience will remember your carefully crafted message.

So how can you improve on those odds, and help your audience remember more of what you’re telling them?

First of all, a recent study on why we forget suggests that once we’ve learned something, the brain deliberately forgets some of the route established on the way to the knowledge. It’s as if, once you’ve figured out how to pedal a bike, you throw away the training wheels. The reason? Mental efficiency. You don’t want to clutter up your brain with lots of redundancy.

This aspect of memory suggests that mere repetition in speaking is a double-edged sword, helping those who still haven’t learned your message, but working counter-productively with those who have learned.

Another study shows that learning, spatial relations, and changes in the structure of the brain are all connected. Memory is strongly associated with physical movement and place. It may be that the original reason for memory has to do with locations as much as anything else—knowledge of food and water sources, danger, your cave, and so on. So to help people remember things, get them moving around. And take heart – the brain actually changes its structure to learn things about new places. So you can improve their memories, if you use place and motion to induce brain structure change.

Another way to boost memory is to repeat what you’ve learned in a special way – out loud to someone else. That other person doesn’t even have to be listening, just present. Repetition without the other person is relatively ineffective.

And still another study shows that you can boost retention considerably by getting a person to rehearse what you want them to remember – for 40 seconds. That period of rehearsal allows for mental consolidation and greatly increases the likelihood that you’ll retain the material you’ve spoken out loud.

The idea is to have the audience consolidate what you’ve said to them by getting them to repeat a structured version of your material.

These memory studies and techniques point to ways that speakers can greatly increase the amount and quality of what their audiences remember of the presentation they’re hearing. By getting the audience to do some work in the moment, repeating your material with a new structure, talking to someone else about what you’ve said, interacting with the material in more than a passive way, and so on, you can ensure that the audience remembers far more than they are likely to now.

Both you and the audience will be grateful.

But of course the most powerful way to get your audience to remember what you’re telling them is to share powerful stories. That’s what I teach in my online course, Presentation Prep: Ten Steps to Persuasive Storytelling – check it out here. The only reason to give a speech is to change the world, and the world can’t be changed if the audience forgets what you’ve told them.