This brief interview with MIT neurobiologist Matt Wilson, posted on the TIME website a few days ago, is an interesting addition to a long-standing debate about memory: do people recall good or bad events more easily?

Convincing research exists for both arguments, but according to Professor Wilson it’s much easier for people to recall negative occurrences:

“We think of memory as a record of our experience. But the idea is not just to store information; it’s to store relevant information. [The idea is] to use our experience to guide future behavior.” “…The speculation is that we process memory in order to solve problems. And things we should learn from, things that are particularly important or that have strong emotions tied to them, may be things that are going to be important in the future. If you present stimuli with a strong negative emotional component, the memories do seem to be more easily retrieved than neutral stimuli or even those that are somewhat positive…”

Other studies run counter to Walker’s ideas, however, such as this 2003 Review of General Psychology article by W. Richard Walker et al. entitled “Life is Pleasant – and Memory Helps to Keep It That Way!”.

In the study, the authors found that people generally show a positive bias toward past memories, for two reasons. First, people “perceive events in their lives to more often be pleasant than unpleasant”. Second, “the affect [feeling or emotion] associated with unpleasant events fades faster than the affect associated with pleasant events,” a phenomenon known as the fading affect bias.

Depressed people were an exception to the rule – they tended to exhibit less “fading” behavior. Overall, though, Walker and colleagues concluded that “these biases allow people to cope with tragedies, celebrate joyful moments, and look forward to tomorrow.”

So, what conclusions can we draw from these contradictory research findings? First, it’s important to note that our memories are not unchangeable recordings, as we like to imagine. Even Wilson admits this, adding towards the end of his interview:

“[Emotional content] does not necessarily mean that events are remembered more accurately, and that’s an important distinction. In fact, there’s a lot of evidence that all memories can be altered. It’s a normal process — we’re constantly taking our experience and revising it, even twisting it to our own benefit.”

Unless something is so traumatic as, say, the September 11, 2001 World Trade Center attacks (an example offered by Laura Blue, who interviewed Prof. Wilson), I like to think that time really can soften the blow of negative events, as with Walker’s fading affect bias. I have certainly found this to be the case in my own life – the painful feelings associated with negative events fade gradually over time, while happy memories reliably make me feel good when I recall them, no matter how long ago they took place.

The Persistence of Memory: Are Negative Events Easier to Recall?