I've seen it happen often enough. A senior leader is present and no one says much until the senior leader does. People then fall over themselves to comment, with the comments leaning towards different ways to restate what was just said or to pander to the leader. Group think kicks into over drive, and anyone who had an out of the box thought quickly buries it along with their pride.

This often happens because the HIPPO (the Highest Paid Person's Opinion) is crushing any diversity of thought in the room. While this sentiment isn't true for every leader that happens to be the highest paid person in a room, it applies to enough to be worthy of further discussion. And it's exactly what Wharton organizational psychologist and author Adam Grant recently posted about on LinkedIn.

Stanford professor Bob Sutton responded to Grant's post by adding that the HIPPO is also often like the namesake animal in that they have a big mouth and little ears (they're prone to talk much and listen little).

As for Grant's advice to have everyone else in the room share their views first, I've done that as the HIPPO, and it can be effective, as long as (as the leader) you've established a baseline of trust. You also must have shown that you value others opinions and that you'll commend, not condemn the opposing point of view and reward contributions from all.

But sometimes, even then, employees are still hesitant to speak up --for fear of the criticism they might receive if there is disagreement with their point of view. Having coaxed employees for three decades to speak up and speak their minds, without fearing criticism, I can offer four ways to encourage them to raise their hands and share their voice.

1. Use the movie critic metaphor.

Theater critic Albert Williams once explained why theater critics do what they do. It's not because they're mean-spirited or want to save you 13 bucks by not watching a crappy movie. Williams said they're driven to help create better art. You can encourage employees to view critical feedback the same way, intended to create better art, in the form of better input, better quality ideas, a better version of the employee.

So share this metaphor with employees and remind them that criticism is intended to create better art in the form of a better them --which only happens if they speak up. I also used to say to employees, "Let criticism feed you, not your insecurities", and "It's about seeking improvement, not approval."

2. Share the dangers of avoidance.

You can also share what happens when you don't embrace criticism. Tell employees that avoiding criticism is what makes them weaker, not the criticism itself. Tell them that avoiding criticism means they're withholding their gifts from the world. Remind them of the powerful quote (debated as to whether Aristotle or writer Ebert Hubbard said it), "The only way to avoid criticism is to do nothing, say nothing, be nothing." And ask them, "On your deathbed, will you ever say 'Whew, I avoided criticism'?"

3. Use the principle of distancing.

The distancing principle says that leaders should never make criticism about the employee as a person, it should be about their output or behavior. This is a reminder to depersonalize any criticism or corrective feedback you might give. This is similar to what psychologists teach about correcting a child, never make it about them as a person, it's about their actions or behavior.

So keep this principle in mind with your troops. Tell them, "I want a culture where everyone feels free to speak their minds. If I offer criticism or pushback on what you have to say, please don't take it personal."

4. Remind them of the law of worth.

The law of worth says that anything worth doing attracts admiration and criticism. It's worth it for employees to speak their minds, so much good can come from it. Especially if you're the leader making sure no bad comes from it (within reason). If you want to "dent the universe" as Steve Jobs famously said, sometimes you have to take dents in your armor. That's just the way of the world and it's nothing to be afraid of.

So if you're the HIPPO, encourage employees to weigh in and not get crushed under the weight of what you say.