To accelerate memorization of a fact, statistic, vocabulary item, or other consolidated piece of knowledge, close your eyes. When the eyes are open, brain energy is being used to take in information from the environment. Closing our eyes can increase focus/processing power. .
Whenever we blink—and close our eyes—our mind temporarily stops taking in visual information from the environment. My experience is that we can channel some of the brain energy used to seeing on something else—like a piece of information—which improves our ability to absorb it. People commonly close their eyes to increase focus (praying/meditation/love-making etc.) This is simply another application that occurred to me while studying.