Focus, Attention, And Mental Filters

[zoobyshoe]

Since I got interested enough in Neanderthal man to start reading about him, and because this leads to questions about whether or not modern man could have bred with Neanderthal, I have found myself getting into the habit of constantly checking out the slope of the foreheads of every person I now see. This has become a habit: I do it automatically, and don't make any effort. I realized today that I'm hardly paying attention to any other aspect of people's faces anymore: I'm just keeping an eye on everyone, waiting fo them to offer that profile view so I can gage the slope of their forhead.
This is a pretty extreme example of an odd mental filter. Throughout my life I've gone through a long succession of less bizarre ones. Another one I can recall is going around paying particular and exclusive attention to color. This has happened a few times, sometimes in conjunction with being heavily involved in artwork, and sometimes because of reading about how the eyes and brain create and percieve color.
I wonder if anyone else has any examples they recall of especially strange mental filters, like noticing the slope of peoples' forheads all the time?

[Danger]

I always notice handedness. Although I haven't done a real survey yet (I'm going to), it appears that about 40% of our customers are lefties.

[hypatia]

Some years ago I started cutting silhouettes, just as a hobby. Not just people but plants and animals too. Befor long I began to view almost everything in a black and white profile.
And there was one time I would catch myself looking at growth patterns of body hair on males, well that was a weird summer anyways.:redface:

[hypnagogue]

What exactly do you count as a mental filter?

[zoobyshoe]

What exactly do you count as a mental filter?
If you're concerned I'm not using the term here rigorously, I probably am not. If it helps clarify: both Danger and Hypatia gave good examples of the sort of thing I was thinking about.

[hypnagogue]

I'm not worried about rigor, I'm just genuinely not sure what you would consider to count as a mental filter. Do you just mean regularly noticing certain things that you normally/previously wouldn't think twice about?

[zoobyshoe]

Do you just mean regularly noticing certain things that you normally/previously wouldn't think twice about?
I mean extreme examples of paying attention to one phenomenon, dynamic, or subject, to the exclusion of others. If, for example, I go around specifically paying attention to the colors of things, I am not noticing their shapes, and I am also not paying attention to the sounds around me, among many other things I might notice if I weren't so focused on one sort of thing.