Tania Luna, the co-host of the podcast Talk Psych to Me and the author of the book Surprise, describes the phenomenon as an error signal our brains produce when something unexpected or mis-expected happens. Luna believes it was an essential adaptation for our ancestors because it forced them to freeze and focus on threats and opportunities, while those who could not experience surprise could not react or learn quickly enough to survive.

"On a neural level, surprise is a dopamine trigger, producing the neurotransmitter that drives attention and motivation," Luna explained in Psychology Today. "To put it simply, surprise is a big deal to our brains. It makes us stop, notice, and learn." That's why we remember the times someone (or something) got us so vividly.

In his book The Power of Surprise, psychologist Michael Rousell reveals his favorite insight gleaned from decades of his research: surprise is a key ingredient in our formative moments. (Formative events are the experiences that have shaped who we believe we are. They form our sense of self.)

All of us are influenced by the combination of our past experiences, and the majority of our experiences are part of a slow, gradual evolution in self-perception, except for the formative events that are like a sudden revolution, resulting in a sudden shift in how we perceive ourselves.

To help understand this concept, Luna suggests this example: it took Hector many years to develop the belief that he lacked leadership potential. And it only took an instant to change his beliefs when a coworker told him, "Most folks on our team just want to hear themselves speak, but you listen and make sure everyone feels heard. You are a great leader, and you inspire me to be better too."

"This simple comment was the surprise spark that transformed Hector's self-image," Luna said. "After hearing that, confirmation bias triggered Hector's search for confirming evidence, causing him to re-label his past experiences from 'people-pleasing' to 'great leader.' The result wasn't just a change in his thinking but also a catalyst for 'self-fulfilling prophecy' actions such as volunteering for more leadership roles."

An example Rousell shares in his book is this: Samantha felt her shyness was a weakness, until her swim coach surprised her by naming her captain. He said, "She may be quiet, but when this girl says something, you're going to want to listen."

The surprise left her feeling quietly powerful, and the change in her beliefs and behaviors was instant and long-lasting.

But not all surprising moments are created equal. If you too want to catch your family member (or anyone else for that matter) off-guard, Rousell thinks there are three research-backed steps to use surprise well.

The first is to identify a perceived weakness: spot a self-criticism you'd like to help someone revise. For example, perhaps your student sees herself as a slow learner, your employee believes he lacks creativity, or your spouse beats themself up for being overly cautious.

Then transform the weakness into a strength. To do so, identify the strength that is the opposite side of the same coin. For instance, maybe the student who thinks she learns slowly is also very thorough. The employee who thinks he lacks creativity is highly logical. And the flipside of your spouse's concern is their attention to detail.

Lastly, deliver the message. Share your sincere perception of the individual's strength. Rousell suggests making your message quick and to the point, as if you're stating an empirical fact. The more you dwell on the topic or dress it up as flowery praise, the less surprising it will be, and the less power it will have to change someone's mind.

"Surprise has the power to help others change how they see themselves. But, crucially, it also gives us the power to change how we see ourselves," Luna wrote.

Possessing these new skills, you can now act as an agent of surprise—unlocking people's confidence and self-esteem wherever you go.