There are two things that had a significant impact on the way I handle peek-based effects. The first was the testing behind the 10% Peek. The second was showing people a well-known mentalist doing a center-tear where the information is glimpsed in the process of tearing the billet and having many of the people watching it say something like, "He looks at the word while he's tearing it."
Strip away everything you know about peeking and assume you're a layman. You're asked to write down a word (or draw a picture or whatever) and then hand that word/picture to the magician. You are never going to be more suspicious about what's happening than when you first hand that information to the performer. And yet, that is often when the peek occurs.
Here are the precepts I follow when peeking information that I find work best in my performance situations.
1. Don't Peek When Their Guard Is Up
I'm sometimes amazed that the idea of peeking the word during the process of doing a center-tear took off the way it did. There may be real logistical reasons to do it like that—for the sake of pacing and getting it done quickly. But for the sake of deceptiveness I think it's a step backwards. I think magicians/mentalists just like it because it's more clever.
Imagine that was the original way of doing the center tear (peeking the information mid-tear). If someone had come forward and said, "I've come up with a way to do the center tear where you can legitimately turn your head away, and close your eyes during the tear and immediately flush the pieces away or toss them in a fire or throw them off a cliff." Everyone would see this as a big improvement. But that's genuinely what you can do with the center tear when performed the "old" way.
Trying to surreptitiously glance the information as you tear it is a loser's proposition. Just Occam's Razor it. The notion that you can get a glimpse of the information as you tear the paper up isn't that hard to conceive. (I would say it's easier to conceive that than that you could casually tear around the needed information and then conceal a hidden piece to read later.) Especially because they often do see you looking at the pieces.
"Oh, no, Andy. I demonstrate how they should hold out their hand to take the pieces so their mind is occupied and they don't see me looking at the word. They think I'm just looking down at my other hand." First, I think you're under-estimating people abilities to gauge sight-lines. And second, while I think it's a good idea to get the glimpse under the guise of something else, you can't expect people to forget what's on the forefront of their mind because of some lame justification.
Imagine you're on a business trip with a sexy co-worker and because of some hotel snafu, you have to share a room. The bathroom is too tiny to change in so after her shower she needs to change in the room itself. You turn your back to give her privacy and every time she glances your way it's clear you're not looking at her. Your lack of guile in this moment—when she is most vulnerable—will go a long way towards building trust and allaying her suspicion.
If, on the other hand, she comes out and is slipping into her clothes and while she does that you turn and say, "Did I leave my cell phone over there?" And give a half-hearted attempt to shield your eyes, she's going to know what's up. Magician's will say, "Ah, but I fooled her by justifying looking over there as if I was trying to find my cell phone." No. Your weak justification isn't enough to make someone forget their primary concern in that moment.
Similarly, if you write a word down, I tear it up, and glance at it at the height of your suspicion (and when you hand me the word you wrote down it's going to be the height of your suspicion) even if I give some alternate reason for glancing in that direction, you're going to know what's up. You might not understand all the details, but I've concentrated the moment where something funny happens to such a small bit of time EXACTLY when your guard is up that I don't really give you any other option but to suspect it happened when it did.
Don't peek when they're expecting it. My general rule is that I like to have my head turned away completely during the time where I'm dealing with the logistics of them giving me the information. When I'm placing the billet aside, or ripping it up, or putting the business card with the drawing in my wallet, or handling the cards during the process of them looking at one, these are all the moments when I look nowhere near the information.
Even if you feel like you have a decent justification to look towards the information (like that one where you act like you spazz out and can't put your wallet back in your shirt pocket so you need to look down to guide it in), wait it out and do it a little later when their guard is down.
2. Insert a Time Delay
There should be a break in the action before you peek the information. This is what will allow your peek to take place at a point in time where there's less heat. If you take the picture they drew on the business card and put it in your wallet and then immediately start saying what the picture is, then you're suggesting you got the information in that small portion of time when the card was put in the wallet.
Similarly, if you take the billet, rip it up, then immediately start saying what you saw, you're drawing all the attention to the moment where you took and ripped the billet because that's all that happened.
Magicians and mentalists are always concerned about justifying why they rip the paper for the center-tear and why they have to put the card back in the wallet for a peek wallet. But those moments are much less problematic if they're not the only thing you do before revealing the information.
Instead, give them more to think over by extending the process. Take the drawing back and, with your head turned away, put it in your wallet and set the wallet aside. "We'll get back to that in a moment." Shift gears slightly, insert a time delay, and you can catch people off guard when you get the peek later. They are no longer at the point of highest suspicion. So when you move the wallet later on you're no longer under the same amount of scrutiny as you would be right after getting the drawing.
3. Start the Reveal of the Information Before the Peek
Whenever possible I try to do this. It definitely messes with people's ability to formulate a hypothesis of when and how you figured out the information.
So let's say I have you draw any animal and slide the drawing into my wallet, site unseen. The wallet is set aside. This all happens while my head is turned. Now I talk about something. Maybe the parable of the blind men and the elephant. I ask you to imagine touching different parts of this animal you're thinking of to see if I can pick up on the feelings and assemble them into the right creature.
I concentrate. "I think I'm getting it. There's hair on this animal isn't there." If you say yes, then I'm all set. I can say, "Yes. It's not a bird or a fish or a reptile. But it's not all fur or hair. There's...." I trail off. I start rubbing my fingers against my thumbs as if I'm feeling what they're feeling. "Touch the different parts of the animal in your mind again. Yes... I'm getting a different sensation. Almost like maybe... leather almost?" During this I'm touching different things on the table. Trying to find something similar to what I'm feeling. When I say "leather," I pick up my wallet and rub my fingers against it and peek the information as I'm squinting and trying to place the feeling. Then I just play off whatever I see. If it says "dog" I don't immediately say dog after handling the wallet. The wallet is set aside and I continue on with trying to feel the animal. "But not smooth like that. It's more rough. There's a lot of hair or fur on this animal, but also this rough area. Oh... I know what that feels like. It's like a dog's nose or his paws or something?" Of course you adlib something that makes sense depending on what you see.
The idea is just to start the process pre-peek which will screw with their timeline if you never even looked in the direction of the written or drawn information.
(But what if you're wrong on your guess? Well, I think that's not an issue. Being wrong on some sort of 50/50 guess early on in the process isn't something I'd have a hard time talking my way out of. So, for example, I say the animal has fur and they say no. "Hmmm. Okay. Well I'm getting some sort of texture." Then I'd rub my arm a little. Rub the table. Pick up the wallet and rub that (getting the peek). Rub my shirt. This is all as if I'm trying to place the feeling I'm picking up. "Feel the animal in your mind again.....I'm still getting something hair-like." It's definitely not a fish or a snake. "Oh... it could be feathers." I'd then be feeling around as if the feeling of the animal is manifesting under my hands. "But not a normal bird. Oh, I know... I think it's a penguin.")
4. Justify Your Gaze With a Motivated Action
You need to justify your gays. Remember, god created Adam and Eve, not Adam and Steve.
Whoops... confused this with my other blog (justifyyourgays.biz).
The final step is to get your peek under the guise of a motivated action. In the above example I look at the wallet in the moment I'm feeling it. Which makes sense in the context of that routine.
In the routine posted Monday, he gets the peek as he asks if the item the person is thinking of is bigger than the wallet.
If you've stolen out the center in a center-tear then you have almost unlimited justifications to peek the information because you're apparently not looking where that information is anymore.
If the information is in a gimmicked stack of business cards, don't look anywhere near the stack until you've had some kind of time delay. Then you can clear the table for some reason and set the stack aside and get your peek at that point in time.
The key word here is "motivated." A motivated action has a "because" in it that is obvious to the spectator. "He picked up the wallet because he wanted to feel it." "He picked up the stack of business cards because he wanted to clear the table."
It's these factors taken together: not peeking at the height of their suspicion, including a time delay to take the heat off the location of the information, starting the revelation before doing the peek, and then obtaining the peek in a motivated action, that I've found generates the strongest reactions from effects that are peek-based.