If I understand correctly what you want, it can be much easier - no need for expressions.
As you probably know, After Effects features a very powerful text animation engine, based on the idea of animators and selectors. I suggest you take a look at the whole chapter about Animating text in After Effects Help.
Essentially, a text animator is a property group you add in the timeline that has two basic elements - a number of properties you add for animation (position, scale, rotation, tracking, fill color, and many others) and one or several text selectors, which are the ones used to pick which text elements are affected by those properties. Animation happens above all by how some text elements go in or out from a "selected" state to an "unselected" state, going through everything in between. The beauty of this all, is that it only takes a couple of keyframes to control dozens of characters. And you can do this very quickly, once you master the basics, instead of fighting with a thousand layers like it used to be.
In this casem I believe you can achieve what you want by creating an animator for position with a wiggly selector: Twirl open the text layer and in the "Animate" menu select "position". You will see this animator has a range selector inside (this is the default selector). Delete it and in the "Add" menu next to the Animator you created, choose Selector > Wiggly (the wiggly selector is about assigning each character (or word or line if you want) a random selection intensity that changes x times per second. This intensity (amount) sets how strongly the position (or other properties in the text animator) value affects that character/word/line. So, if the wiggly selector assigned an amount of 30 per cent for the second charcter, that means it'll receive 30 per cent of the position vaue specified in the text animator. And this amount changes all the time, based on wiggles per second Confusing?
To imitate this "cold" feeling you probably want to set the wiggly selector to something fast (wiggles per second) in a short distance (small position values). You can set the wiggly selector to create random amounts on a per-character, per-word, or a per-line basis, depending on what you need.
Let us know if you need more help.
Thank you Mr. Rozenfeld. That was a thorough explanation. I will definitely look into that chapter, it's
just I looked in a part of it related to the Wiggly Expressions and it gave me difficulty. But your tips were a bit easier to make use of. Thanks a mil.
Expressions are wonderful. But I wouldn't recommend them as a starting point for these things.
The text animation engine is a very good example of how AE works really hard so thing that required dozens of layers and dozens of keyframes now can be made in minutes. The price you have to pay... is learning it
It may seem complicated, but it's just deep and powerful. I think you may find it is a lot of fun once you get your feet wet.
In case you find it useful, here's an example (AE CS4) project that shows characters or words entering this "cold" animation and then returning to the original state. Just a couple of keyframes in the wiggly selector for Max and Min. amount (ie, the maximum and minimum intensity that each character or word can have).
freezing.aep.zip 8.5 K
The wiggly Selector may be a little hard to find. Here's how you do it.
With your text selected in the time line choose Animate and pick a property. For shivering letters I'd probably use scale. You'll now have an Animator 1 property in the time line. Directly to the right you'll see add. Click there and you have the option of a property or a selector. Choose Selector and you'll find the Wiggly option. Now you'll have a bunch of options available for wiggles/second (never need to be higher than the frame rate) phase, min and max amount.
I'd then unlink the scale property and set x scale to something like 95% and y scale so something like 110%. Set keyframes for min and max amount and you're done. You might also want to add some skew to your animator 1 and turn on motion blur.
Hope this helps.