"Oh, wait... I know this line. I can see it on the page... uh, the top of page 40. Argh, I can't remember... How does it start?"
I've heard so many actors say that sort of thing in rehearsal, and I can tell you exactly why it happens: memorizing from the page. In performance, you'll have to speak the lines, so you must use sounds (hearing and talking) for memorization early and often.
Of course, all you have to start with is the script, or your Complete Works of William Shakespeare. The problem is: if you keep using the written words to learn your lines, you'll "see" the text, and you'll have to "read" them each time you recall them. It also slows down your reactions to other characters for the same reason: you memorized the cue line as text. When you hear it said, your brain has to translate what you heard into text, recognize that it's your cue, retrieve the correct response line (as text), then translate it into the sounds you speak.
I can hear the outcry: "I have always memorized from the page, and I'm really good at it. I don't hesitate, and I don't see words floating in the air either. Poppycock!"
So, let's go over some proven facts:
1. Just because you're not aware of a mental process, doesn't mean it isn't happening. You'll never see magic text that you actually read... but the act of switching between modes of recall (vision vs. sound) takes mental energy away from your acting - and that is visible to the audience.
2. It's a tiny gap. For a natural English speaker, the translation between text and sound takes milliseconds. But that tiny pause is the difference between natural conversation and the recitation that kills so many performances.
3. The extra layer of processing harms your recall. Even if you're accustomed to learning your lines from the book, you'll find it easier and faster to learn by ear.
Have you ever noticed that you learn other actors' lines really easily during rehearsals? When they blank or call "line!", are you faster than the Stage Manager in feeding them their next words? That's because hearing Shakespeare is like hearing song lyrics (that's why they call it verse). Learning the lyrics to a song comes naturally from hearing it repeatedly, not from reading the lyrics sheet every night.
And when you hear other actors in rehearsal over and over, their lines get stuck in your head. Then it comes to your line, and you mess it up. Why?
Because you don't hear your own lines over and over... unless you get creative.
Some actors (including myself) record lines onto a mini-tape recorder. I hear only my own lines, and repeat. It's effective, but clunky. Here's some reasons it's not ideal:
1. Rewinding: Whether digital or mechanical, to go back a few lines to drill them is a pain.
2. Rhythm and tricky words: Even if you try to record with no emotion, what do you do about "incarnadine"? You can't record past that line until you check with the director about pronunciation.
3. Cues: To perform dialogue well, you should learn your cue lines by ear as well. However, you shouldn't listen to the same voice for the cue as the line, or you'll screw up even worse. So what do you do, get every other actor to record onto your mini-tape as well?
So
Memorize Shakespeare has done it all for you. Select the character you'll be playing, download the lines and cues albums, and play them on any mp3 player, or burn them to CD.
Besides learning your lines faster and more reliably, you'll find your acting improving. No more translating between visual and sound... you hear a cue, you say your line.
"I can't remember... How does it start?" Right here:
How To Learn Lines In Shakespeare