Are movie production companies hiring people to rate their movies on IMDB?

I noticed that older movies with a 7 - 7.5 rating are really good, while 2012 movies with that rating are quite bad, and they would most likely be rated 4 - 5.5 in 2004 for example :)

Also newer movies have many more votes then older ones. I've heard companies hire people to register random accounts and rate their movies. Is this true? IMDB ratings don't seem to be reliable anymore

Answer

I've some experiences in freelancing. I guess this answer is correct because I've seen numerous job postings like this to give positive reviews. But one point to be noted is that, to stop this sort of rating manipulation, IMDB only counts votes from regular voters. That means if you just register and give couple of movies very high ratings, you votes are not going to be included in the calculation.

Anyway, I've another explanation, but I don't have any proof to back it up. Old movies are seen mostly by people who really love movies and passionate about them. They are more like movie critic type. On the other hand, new movies are seen mostly by general audiences. And I believe ratings from critics are most of the time less than the ratings from general audiences. So for this reason, being equal in quality, newer movies enjoy better ratings than old movies.