I disagree with you VERY much. I've seen it too many times on heavily and even moderately pressured areas. They do and will learn to look up. I've seen it too many times personally. Usually it's triggered by something else, they smell something, or something isn't quite right......but they can and will learn to scan the trees when they have been educated to do so.

I know it's not a tree, but just a perfect example of how they do have the cognizant ability to learn...........and an example that I know another member here will back me up on.

At my camp, I have a food plot 320 yards in front of the cabin. We watch and observe the deer in there quite a bit. Last season, on the first two weekends in a row I had a certain mature doe with twin fawns bust me in the blind that sits on the edge of that plot. First time was due to the wind shifting, and the second time I honestly have no idea what put her on alert because wind was perfect, and there was no way she saw me in there. On the Sunday of that second weekend, I remember sitting at my cabin 320 yards away (can't hunt Sundays) the day after she busted me there, and watching her come out into the plot,on pins and needles.........staring a hole through that blind. No one was in it, but she was looking and after she had a stare down with the empty blind for several minutes....she bounded off with her tail up in the air, stopping to look back at the blind several times. The next weekend (3rd of the season) found Rob and I in that blind. Same thing, wind was completely in our favor and she had nothing to lead her to believe something bad was about to happen, but she was on pins and needles again staring directly at Rob and I in that blind (wearing all black in a blacked out blind). That doe had without a doubt "learned" that something was in that blind and checked it out thoroughly every time she went into that plot. My father watched her all season long as well and said that she would stare at the blind before entering the plot and actually eating. She almost got away with it a 3rd time that weekend,but Rob managed to let the air out of her before she got another lesson in how to outsmart a hunter.