Masters of persuasion have an edge in an entrepreneurial career, because they leave investors convinced it was their own idea to invest.

In 1957, thousands of Americans watched captivated as a soft-spoken, unassuming New Yorker persuaded 11 people to change their mind by casting a psychological spell. His method of persuasion was so unobtrusive, the 11 hardly noticed his extraordinary manipulation.

In Sidney Lumet's classic film 12 Angry Men, 12 jurors deliberate over whether a teenage boy has stabbed his father to death. At the start of the film, 11 jurors are convinced the boy is guilty. At the end of the film, all 12 jurors are convinced that he is not.

One man -- Juror 8 -- single-handedly changed every mind, one person at a time, without once raising his voice, asserting authority, or injuring anyone's pride. His tactics offer a master class in the art of persuasion.

Here are five strategies he used:

1. Never say someone is wrong.

Juror 8 sets the scene by telling the other jurors that while he emphatically "doesn't disagree" with them, he is "not sure" the boy is guilty.

When someone tells you you're "wrong," they threaten your authority. By saying he is "not sure," Juror 8 weakens his own authority. 

The other jurors now feel safe in the company of Juror 8. Since our brains are wired to loosen hold on strongly held opinions when we think we're safe, the jurors now become more open to persuasion. 

 2. Be persuaded -- don't persuade.  

If someone tries to change your mind, you feel manipulated. If they ask you to change their mind, you feel validated. 

Juror 8 asks the other jurors to help him understand why the teenage boy is guilty. As they do so, they unwittingly place their own logic under the microscope and spot weaknesses they hadn't spotted before.

The jurors are now less reluctant to change their own minds. 

3. Create emotional impact.

Juror 8 has a knife that will prove the 11 jurors wrong. To create maximal emotional impact, he emphasizes what everyone believes to be true. When their agreement reaches a hiatus, he slams the knife on the table and mesmerizes the room.

When a group of people share an emotionally moving experience, some features of their brain waves become synchronized. This can correlate with everyone's brains processing information in a similar way in that specific context.

In the setting of a shared, emotionally powerful experience, the logic that compels you to adopt an idea becomes more likely to be compelling to those around you. The 11 jurors are now easier to persuade.

4. Amplify with attention. 

At this point in the process, Juror 8 has nudged a few of the other jurors into switching sides or sitting on the fence.

Attention acts like a magnifying glass. If your spotlight of attention falls on one outlier opinion in a crowd, you assume the outlier represents the overwhelming opinion of the crowd.

Juror 8 makes use of this when he shines the spotlight of the room's attention on those who appear to have changed their minds by asking them, "What do you think?"

The spotlight creates the illusion that their minority opinion is now the consensus. This creates a "conformity" pressure on others to also question their opinion and change their minds.

5. Trade emotions for rationality.

Persuasion is a sophisticated tango of emotion and rationality. While emotional arousal creates synchrony, rationality allows people to appreciate the logic in your argument.

Emotionality and rationality don't, however, go hand in hand. If you've aroused your audience with emotion, they will not be able to process complex, nuanced arguments until their emotions are calmer. 

Juror 8 takes this into account by creating synchrony with emotional impact early on, and harnessing this synchrony later on with nuanced, complex arguments when emotions have settled. 

Your mind is private property.

Juror 8 created the illusion he had nothing to do with changing the other jurors' minds.

The mind is private property. If ideas try to enter this private property by force, we feel the need to reject them. We dislike uninvited guests -- we only want ideas we have invited in.

The art of persuasion lies in getting another person to feel safe enough to unlock their gates and invite in ideas they have peered at cautiously over the fence, so the ideas end up staying for dinner.