So I'm rewatching LotR Fellowship of the Ring at present and some of the CGI is standing out to me as "fake" more so than it ever did in the past. Now I admit its been a while since I saw the film so its a little more fresh to me than it was. Now many will say "ahh the CGI looks weaker because its older and CGI today so so much better". And that is true. CGI improves all the time, especially with the higher ends of the film industry. However it still doesn't really answer why it stands out in individual films more so over time. In theory it shouldn't matter if new CGI is better as the old hasn't changed as a result; so it should still be as impressive as it once was. Thus I'm coming to the conclusion that CGI works partly by mind tricks. Our mind sees partly what our eyes see, but because our mind has to interpret information its also capable of being tricked. There are many instances of this and I think films are one of them. The first time we see a film we don't know what to "see". We don't know what to expect and thus the film is fresh and the mind has little time to really "think" on what its seeing and takes it at face value more so. Thus the CGI blends in far more easily. However as time passes we get used to seeing the same film, we start to "see" more so rather than let our minds be clouded by what it thinks we should see. I think then the CGI starts to stand out, we pick out the smaller differences and it loses the ability to trick our minds. Of course the weakness with this theory is that it makes the assumption that we remember the film; or at least have some relation with it mentally that allows us to change how we view it over time.