Her eye movements are so unique a while back after one of the hearings I finally sat down and watched the hearing in slow motion to watch her eyes in more detail. I finally thought she has more than a habit of looking back and forth, I think she has some condition, maybe something like a very slight "Nystagimus" or something similar. (I had known someone who had it years ago and it looked familiar, had to look it up to find the name, I think that's close, please excuse my spelling!.

). When she's looking at someone in the face her eyes tick back and forth as if looking at the other person's left eye then right eye repeatedly. When you try doing this you discover how unnatural and tiring it is.
I know in some brain conditions, people don't see other people's faces as an integrated whole but only see one feature at a time. Or, there are eye conditions where the eyes will simply shake left and right like this. For some people it's a hereditary thing (like my friend), for others it can be related to a health condition or brain injury, etc.
When she's looking in a mid-range type area, not right at someone's face, just sitting there looking into space more or less, her eyes will often follow this repeated pattern:
she starts out looking straight ahead, but her irises then drift left and slightly down. At this point she usually blinks and her eyes correct themselves by jerking back to center. Her eyes do this over and over a lot of the time. This drifting and jerking is what made me look up nystagimus. Again, it's not all the time, but you can tell watching it that it appears to be some kind of involuntary thing.
Once I saw her eyes go completely still. This was very unusual for her. It was when she was watching one of the forensics gentlemen in one of the hearings answering JB's questions regarding collection of hairs and insect evidence, and I think there was mention of decomposition. Casey's eyes were open very wide and she stared like that for a really long time without blinking, as if in a trance. It looked like she was somehow trying to understand and take in what he was saying by opening her eyes extra wide, but like she still couldn't take it in. It was very unusual, most people couldn't stare like that for that long without blinking. She looked kind of confused and surprised/dazed, like the reality of the situation was almost registering with her in that moment that this was Caylee they were talking about, but it could not quite get through, she finally snapped out of it and returned to her busy/oblivious/compulsive mannerisms.
Anyway I do wonder about her eye movements and whether she may actually have some condition that causes some of it. Nystagimus (I hope I'm not spelling that too badly) is often just hereditary but it can also be caused by brain lesions/brain injury or a period of severe alcohol abuse resulting in thyamine deficiency, also by some medications and drugs.