Choose your daydreams about old memories carefully in order to optimize remembering of recent events. You can also choose your memory recall daydreams to help you forget.

When your mind drifts, it's hard to remember what was going on before you stopped paying attention. Now a new study has found that the effect is stronger when your mind drifts farther – to memories of an overseas vacation instead of a domestic trip, for example, or a memory in the more distant past.

Daydreaming at all impairs remembering what you are doing. So in the middle of your work day if you are trying to keep track of a lot of facts in a problem or task avoid thinking about who you seduced when you were a foreign exchange student in college.

Psychologists have known for a while that context is important to remembering. If you leave the place where a memory was made – its context – it will be harder for you to recall the memory. Previous studies had also found that thinking about something else – daydreaming or mind-wandering – blocks access to memories of the recent past. Psychological scientists Peter F. Delaney and Lili Sahakyan of the University of North Carolina at Greensboro and Colleen M. Kelley and Carissa A. Zimmerman of Florida State University wanted to know if the content of your daydreams affects your ability to access a recently-acquired memory.

For one experiment, each participant looked at a list of words as they appeared on a computer screen, one at a time. Then they were told to think either about home – where they'd been that morning – or about their parents' house – where they hadn't been in several weeks. Next, the participant was shown a second list of words. At the end of the test, they had to recall as many of the words from the two lists as possible. Participants who had thought about the place they'd been only a few hours before remembered more of the words from the first list than did participants who had thought back several weeks. The same was true for memories about place, tested in a second experiment. Those who thought about a vacation within the U.S. remembered more words than those who thought about a vacation abroad. The study is published in Psychological Science, a journal of the Association for Psychological Science.

Remember an event from a distant country in the distant past when you want to forget something that just happened.

One practical application of the research might be for people who want to forget about something. "If there's something you don't feel like thinking about, you're better off remembering a more distant event than a close event, to try to put it out of your mind for a while," says Delaney. "It can help you feel like you're in a different situation."

What I'd like to know: Does daydreaming about a total fantasy that hasn't happened do as much to interrupt memory formation as memory recall of older memories does? Is fantasy as disruptive as going down memory lane?