When you try to remember something, chances are you look up and away or even close your eyes. This may seem arbitrary, but as cognitive scientist Art Markman explains in Psychology Today, shutting off your vision is actually very helpful when you're trying to dig up information in your brain.
Photo by D. Sharon Pruitt.
So why is this the case? Your brain processes a lot of information and vision is a huge input. Deciphering everything you see can take up a lot of your mind's processing power and so less complex information, like the sky or ceiling or the shade of your eyelids, means it's more available for thought. This is especially significant when you're attempting to recall visual memories. Markman explains:
If you clasp your hands behind your head, most of the area taken up by your hands reflects the amount of the brain that is devoted to making sense of the information coming in through your eyes. Those same areas of the brain are also involved in visual recollections of things that you have seen in the past. It makes sense that the brain would re-use areas devoted to vision to help in memory for visual information.
The same idea applies to other senses as well. If you're trying to remember a sound or someone's voice, complex noises can make the process more difficult. This is why, for example, you may have trouble writing when others are talking. If you hear a voice in your head as you type out a sentence, you'll find difficulty hearing it when your brain is already parsing the existing speech around you. Basically, when you need to remember something, isolate the relevant sense. It'll help you concentrate and find the information you're looking for.
Why Do You Close Your Eyes to Remember? [Psychology Today