It may seem odd that the mere presence of a camera can cause such a disruption in the environment and recalibrate the way we act, think, and feel. Often, the change manifests physiologically. As soon as you are told “you’re on,” your body may send a jolt of adrenaline through you, similar to the one you receive when you stop short in traffic.

Your palms may sweat, your knees may knock, and a giant lump may temporarily block your throat. Why?

Allow me to offer four reasons why the camera changes everything.

No Immediate Feedback—When you’re giving a presentation to a live audience, you’re constantly surveying the room. You’re able to adjust your delivery based on what you see reflected back to you by your audience. But when you’re talking on camera, that lens isn’t giving you any indication of whether your message is resonating or even being heard at all. It feels like your words are being sucked into a big black hole. That uncertainly can undercut your confidence and cause you to seek out reassurance from any source available.

Your Own Worst Critic—Do you remember when you first heard your recorded voice? You probably thought, “I don’t sound like that!” Chances are, what you heard was exactly how your voice sounds—you just didn’t like it. The idea of having to listen to yourself or watch yourself on video can be a painful prospect for many. Analyzing baseline and post-training performances is an important part of any of my classes, yet it is always met with a cringe. The performers always notice things about themselves that no one else does. For example, everyone in the class might be applauding your flawless delivery, but you may be totally fixated and irritated by the way your left eyebrow turns slightly downward. While the entire audience is mesmerized by your powerful presentation, you are thinking about how soon you can get in to see the brow lady. A camera lens can sometimes feel like a microscope, but in this case, it usually makes imperfections only we can see loom large.

Recorded for Posterity—Most on-camera performances can be recorded, and the shelf life of that video, good or bad, will likely be longer than you want. If your video is going to be hanging out on YouTube for who knows how long, you want it to be perfect. That desire for perfection usually serves as the biggest barrier to performance success. We get incredibly self-conscious, which leads to a tremendous amount of pressure and stress.

Unfamiliar Territory—The presence of a camera, even if it’s in your own office or home, can immediately transform the familiar into the unfamiliar. Suddenly, you become self-conscious about things you never gave a second thought. What do I do with my hands? Where do I look? What’s that hum in the background? This hypersensitivity makes it nearly impossible to perform at your best.

If you are in a studio setting, the otherworldly effect is even more acute. You are surrounded by equipment you have probably never seen and likely find intimidating. There are physical obstructions such as cords and wires, which create an obstacle course of a sort, leaving you wondering, “Can I get there from here?” The lights are always brighter than you imagined and cause even the most seasoned performers to squint initially as if it were high noon. Not to mention the whole slew of people who are there, all watching just you.

Why does the camera change everything? Perhaps the question should be “why wouldn’t the camera change everything?”

If you found this information valuable, check out my book, On-Camera Coach: Tools and Techniques for Business Professionals in a Video-Driven World, now available from Wiley Publishing. On-Camera Coach aims to take the mystery out of communicating through the camera and provides specific tips and techniques that can make your message sing—and you, the messenger, feel confident in a job well done.