(CNN) There is a right way and a wrong way to apologize, psychologists say. Over the course of the last few months, we've seen many high-profile examples that fall somewhere in between.

On Wednesday, NBC News announced it had fired long-time "Today" show anchor Matt Lauer amid accusations of "inappropriate sexual behavior in the workplace."

Thursday morning, Lauer released a statement that began, "There are no words to express my sorrow and regret for the pain I have caused others by words and actions. To the people I have hurt, I am truly sorry. As I am writing this I realize the depth of the damage and disappointment I have left behind at home and at NBC.

"Some of what is being said about me is untrue or mischaracterized, but there is enough truth in these stories to make me feel embarrassed and ashamed. I regret that my shame is now shared by the people I cherish dearly."

In late October, actor Anthony Rapp accused actor Kevin Spacey of making sexual advances toward him at a party in 1986. Rapp was 14 at the time; Spacey was 26. Spacey then posted a statement on Twitter the day after the allegations surfaced that read, in part, "I'm beyond horrified to hear this story. I honestly do not remember the encounter, it would have been over 30 years ago. But if I did behave then as he describes, I owe him the sincerest apology for what would have been deeply inappropriate drunken behavior, and I am sorry for the feelings he describes having carried with him all these years."

Spacey then pivoted from the serious allegations against him to confirming a longstanding rumor about his sexual orientation. "I have had relationships with both men and women," he wrote. "I have loved and had romantic encounters with men throughout my life, and I choose now to live as a gay man."

Though all three statements acknowledged at least potential wrongdoing, they did so very differently.

Lauer's statement was short, to the point and contained the words "I am truly sorry."

Spacey said he has "a lot of respect and admiration" for his accuser. He claimed to not remember the encounter, arguing that he was drunk and that it was a long time ago. Spacey did, however, employ the word "apology."

Nowhere do the words "apology" or "sorry" appear in C.K.'s statement, but he too addressed his accusers by name. He also took responsibility for his actions -- no "ifs," "ands" or "buts." He acknowledged the lessons he's learned about the complexities of power (being admired by younger comedians) and expressed remorse.

C.K. concluded his statement by writing, "I have spent my long and lucky career talking and saying anything I want. I will now step back and take a long time to listen."

Lauer said, "Repairing the damage will take a lot of time and soul searching and I'm committed to beginning that effort. It is now my full time job."

How to say 'I'm sorry'

"Comprehensive apologies are powerful tools that transgressors can use to promote reconciliation with the people they have hurt," psychologist Karina Schumann wrote in a 2014 study published in the Journal of Experimental Social Psychology . "However, because many apology elements require transgressors to admit fault, express shameful emotions and promise change, transgressors often avoid these threatening elements and instead choose to use more perfunctory apologies or even defensive strategies."

Schumann, who is now an assistant professor at the University of Pittsburgh , says there are three "core" elements of a good apology:

Express remorse, by saying "I'm sorry" or "I apologize," as well as regret, by saying "I feel terrible" or "I regret it."

Accept responsibility by stating, "I take full responsibility" or "I'm truly sorry for" whatever you did.

Offer to repair the problem you caused by saying what you will do to fix it or by telling the person you've hurt how you honestly feel about them.

If appropriate, Schumann says, an apology may require additional elements:

An explanation of your words or actions.

A promise that you will behave better in the future.

Acknowledgment that you understand how your victim has suffered.

Admission of wrongdoing, such as "It was wrong of me to say the things I said" or "I shouldn't have spoken poorly about you."

A request for forgiveness.

Equally important to what you do or say is what you don't do or don't say.

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"Transgressors may ... try to protect themselves from the negative consequences of committing an offense by responding with defensive strategies," Schumann said. "These defensive strategies can be temporarily beneficial to the transgressor by helping restore his or her self-worth but may do so at the cost of aggravating the victim and hindering reconciliation."

Four things, she says, can torpedo even those most well-intentioned apologies:

Justifying your words or actions by defending your behavior: "I'm sorry that I kicked you out, but I did it for the right reasons."

Blaming your victim for any or all of what you did or said: "If you gave me more freedom, I wouldn't feel the need to be dishonest."

Making excuses: "I was busy and in a hurry."

Minimizing or downplaying the consequences of your actions: "I'm sorry if I upset you"; "it's in the past"; "it was just a joke."

"One of the unfortunate certainties of life is that we sometimes hurt people we care about," Schumann wrote. "But if managed well, hurtful events can be transformed into constructive experiences that might even improve the relationship between the transgressor and the victim."