I've noticed people who drive in a more race-y fashion after playing a fair bit of a driving game (GT and Driver). Not dangerous driving, but more dangerous/less careful. The influence of games is often quite subtle, but certainly there.
Many moons ago I was playing a lot of Captive on the Amiga. My place of work had an area who's layout was similar to captive in that it had brick walls with white guirders dividing it into blocks. One day I was walking down such a corridor and spied a plug in the bottom-centre, and the thought that crossed my mind was 'stick the hand in and get some more juice.' That's when I knew I had played too much!
I expect it would be hard for individuals to measure influences on themselves, because those influences may be very subtle (such as moving more towards the centre race-line around corners rather than staying centrally in the lane). That's where independent research comes in, as long as it's performed properly.