I once attended a social gathering made up of the large private psychologist practice group where I worked and executives at a hospital.

I tried to interact positively with hospital executives. After I left, I saw that I had spinach stuck to the outside of my teeth - spinach from tasty food I ate at the start of the gathering.

It has been 35 years now, and I still remember that incident well and follow my no-spinach rule at social gatherings. Embarrassment is a powerful emotion.

Embarrassment occurs when we think that we are being evaluated negatively by others for something we have done. It can also occur when we expect to be evaluated negatively by others for something we are about to do.

Embarrassment can help motivate us to change our behaviour in the future and to maintain that change. 

Sometimes the change we make has value for us, as in my spinach story. Other times we over-react and start avoiding important situations.

For instance, I might have avoided social gatherings altogether after my incident.

Shy individuals often make that kind of mistake, as they live in constant fear of doing something embarrassing in front of others. They may avoid parties, malls, intimate relationships, and so on. 

Looking back on my incident, I realise that I never saw any of the hospital executives again, and no one ever mentioned my spinach teeth. Maybe I made a poor impression, but the practical cost to me was zero.

Embarrassment can have a positive social effect. Signs of embarrassment, such as blushing, acting disconsolate, and looking at one's feet, can show contriteness for harming a person accidentally.

For instance, a friend visiting my home once dropped and broke a water pitcher. She showed great embarrassment. Her emotional suffering so exceeded the importance of loss of the pitcher that she created a positive impression despite the drop. 

Individuals vary widely in how inclined they are to feel embarrassed.

Neurotic individuals tend to feel embarrassed often. Their habit of negative thinking leads them to expect critical reactions from others.

Psychopaths and narcissists tend to feel little embarrassment. Some politicians and CEOs never show the slightest sign of embarrassment, no matter what they are caught doing wrong. 

As individuals get older, they usually experience less embarrassment, perhaps because they learn that most social mistakes matter little.  

If I see you someday and notice that you have spinach on your teeth, I will consider you a kindred spirit.