We remember the bad times better than the good because our emotions influence how we process memories, a new review of research shows.

When people recall significant, emotional events in their lives, such as their wedding day or the birth of their first child, they're generally very confident about how well they remember the details of the event. But whether or not this confidence is warranted is debatable, because details remembered with confidence often aren’t exactly correct, according to the review of research on emotional memories.

Memories are generally prone to distortion over time, but researchers have found some evidence to suggest that emotional memories are more resistant to the decay processes that wear away at all memories with time, says review author Elizabeth Kensinger of Boston College.

"It's clear that there's something very kind of special and prioritized about how we remember those emotional experiences," said Kensinger, whose review is published in the August issue of the journal Current Directions in Psychological Science.

Bad outweighs good

Negative events may edge out positive ones in our memories, according to research by Kensinger and others.

"It really does matter whether [an event is] positive or negative in that most of the time, if not all of the time, negative events tend to be remembered in a more accurate fashion than positive events," Kensinger said.

While we might not remember more total details about a bad event we experience, "the details you remember about a negative event are more likely to be accurate," Kensinger explained.

The details we are most likely to remember accurately are the things that directly cause our negative emotional reaction. So, for example, if you are mugged, you may remember the gun pointed at you with a high level of detail because it is what caused your fear, but you may completely forget details that are peripheral, such as the things around you on the street or what your assailant was wearing.

"It's clear that there are some aspects of events that are really well-preserved, and then people may completely forget other aspects of the event altogether," Kensinger said, adding that the phenomenon has been documented in research on eyewitness testimony.

The reasons for these sharper memories may be rooted directly in the way our brains are wired.

Memory network

Our brains have a specific memory network that kicks into gear whenever we are trying to remember something, Kensinger said.

"But it seems like when we're having an emotional reaction, the emotional circuitry in the brain kind of turns on and enhances the processing in that typical memory network such that it works even more efficiently and even more effectively to allow us to learn and encode those aspects that are really relevant to the emotions that we're experiencing," Kensinger told LiveScience.

So by narrowly focusing the memory network on the thing triggering the emotion, such as the gun from the previous example, your brain remembers details of the gun very accurately, but "at the expense of devoting any resources toward processing anything else that's going on," Kensinger said.

Conversely, events that we experience as emotionally positive, such as a wedding, or as neutral, such as an average day at work, don't trigger the brain to focus on any one specific detail, so "you're just going to kind of remember everything going on in an equally good fashion," Kensinger said.

This focusing of the memory network during a fear-inducing event makes sense from an evolutionary standpoint, said Kensinger, because your attention is focused on the details that are most likely to enhance your chances of survival if you encounter the situation again. So you want to know what the gun looks like, where it's pointed and whether the assailant seems likely to use it.

"Those sorts of details are critical," Kensinger said. "Whether or not the person is wearing a baseball cap, whether the person is short or tall—those sorts of details, in the immediate kind of survival instinct mode, probably are completely irrelevant."