How long is your to-do list right now? From remembering to buy bread, to calling your mum, to replying to that e-mail, we all juggle any number of thoughts on a daily basis.
But it turns out that trying to keep several things in mind simultaneously can actually end up weakening your memory.
Neuroscientists at the University of Texas have found storing multiple thoughts in our "working memory" causes them to go into combat with one another, fighting to be remembered.
At this point, our brains step in, trying to be helpful. If you were trying to remember to call your mum and reply to an e-mail, and only remembered to do one, whichever one you ended up remembering gets filed away by your brain as more important.
If you remembered to make the phone call, your brain strengthens your memory for making calls, and weakens your memory for e-mailing, to make that subconscious decision easier for next time. Researchers Jarrod Lewis-Peacock and Kenneth Norman wrote:
Close competition can trigger weakening of memories that lose the competition, leading to subsequent forgetting.
The researchers put participants in MRI machines able to detect patterns that show what a person is thinking about. They were then shown pictures of faces and scenes, and asked to remember just the scene, and then describe what it showed. Midway through retelling, some participants were asked about the face, putting both thoughts in their mind at the same time.
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Half an hour later, researchers tested for memory of the scene, and found that participants that had had both thoughts competing had significantly weaker memory of the scene.
So if you tend to fail at multitasking, don't feel bad. In the long run, you may actually be helping your memory out.