The Washington Post recently asked readers to anonymously share their most vivid memories, and these were some of the responses:

“Sitting on my bathroom floor after my father died.”

“My face being forced down to do something I didn’t want to do.”

“The day I heard the voice of God in my head that said, ‘My son, you have another chance.’ It happened moments before I was going to commit suicide.”

But they weren’t all about negative or difficult times. There was the person who remembered a peaceful Easter morning as a child, and the person who remembers the day they met their husband. But readers’ responses were largely retellings of trauma, or traumas turned silver linings.

Many studies suggest that we are more likely to remember negative experiences over positive experiences, and according to Laura Carstensen, a psychology professor at Stanford University, in general, we tend to notice the negative more than the positive.

Some argue that it long predates us.

“Many psychologists think that this has evolutionary roots; that is: It’s more important for people, for survival, to notice the lion in the brush than it is to notice the beautiful flower that’s growing on the other side of the way,” Carstensen said.

Carstensen, who is known for her research on aging, said one school of thought believes that our attention to negative events has adaptive value. She said there’s a lot of information to be learned in difficult or dangerous situations, and that our brains can apply that knowledge when a similar situation presents itself in the future.

But there’s more to it than that: There’s also an age factor at play.

“Emotionally speaking, the worst time in life appears to be the 20s and 30s,” said Carstensen.

Carstensen’s research group is studying what she describes as a “phenomenon”: Paying attention to negative memories is more pronounced among younger people, she said.

“We think what happens with age is that younger people, because they have these long and nebulous futures, really need to collect a lot of information, and so they remember many things that will possibly help them mange those futures,” she said. “The older people get, the more they’re able to live in the present; and so, focusing on positive information makes that present feel good.”

Simply put: Older folks are better at living in the moment and enjoying what’s around them.

Now if you’re a 20- or 30-something like me, don’t panic. Carstensen’s point is that as we get older, we’ll naturally become more likely to focus on positive things.

“Negative emotion is the purview of youth,” she said.

But our memories — much like our style, our Chipotle order and our favorite song on the radio — are ever-changing and ever-evolving.

“We’re constantly refining, pruning memories and letting some of them go while we bring in others and integrate them into networks of memories,” Carstensen said.

Memories are shaped unintentionally by, well, the person staring back at you as you brush your teeth in the morning. We shape (and sometimes reshape) a memory each time we retell it, and we become increasingly confident in its accuracy because we have told it — often as a story to friends and family — again and again, according to Carstensen. She said memory affects our goals at the time something happens, and again at the time we try to retrieve it.

“Memories are fallible,” she added. “Long-term memories are nearly always wrong.”