The whole of the research on this topic has some very, very serious methodological flaws, which mean there is currently surprisingly little evidence that video games or expert gamers are somehow 'special'. In particular, there are serious concerns regarding demand characteristics.
Don't just take my word for it, take a look at the extremely comprehensive and detailed paper by Boot et al. (2011).
It's open access, too!
Here's a choice quote:
One possible factor that could lead to the spurious conclusion of
gaming beneﬁts on cognition is differential expectations for experts
and novices. If gamers are recruited to a study because of their
gaming experience, they might expect to perform well because of their
expertise, and a belief that you should perform well can inﬂuence
performance on measures as basic as visual acuity (Langer et al.,
2010). Imagine that you are recruited to participate in a study
because of your gaming expertise, and the study consists of game like
computer tasks. If you know you have been recruited because you are an
expert, the demand characteristics of the experimental situation will
motivate you to try to perform well. In contrast, a non-gamer selected
without any mention of gaming will not experience such demand
characteristics, so will be less motivated. Any difference in task
performance, then, would be analogous to a placebo effect.
studies comparing expert and novice gamers either neglect to report
how subjects were recruited or make no effort to hide the nature of
the study from participants. Many studies recruit experts through
advertisements explicitly seeking people with game experience,
thereby violating a core principle of experimental design and
introducing the potential for differential demand characteristics
(Boot et al., 2008;Colzato et al., 2010;[Karle et al., 20104). The
problem is ampliﬁed because gamers often are familiar with media and
blog coverage of the beneﬁts of gaming, so they expect to perform better when they have been recruited for their gaming expertise.
Boot, W. R., Blakely, D. P., & Simons, D. J. (2011). Do action video games improve perception and cognition?. Frontiers in psychology, 2.
Boot, W. R., Kramer, A. F., Simons, D. J., Fabiani, M., and Gratton, G. (2008). The effects of video game playing on attention, memory, and executive control. Acta Psychol. (Amst.) 129, 387–398.
Colzato, L. S., van Leeuwen, P. J. A., van den Wildenberg, W. P. M., and Hommel, B. (2010). DOOM’d to switch: superior cognitive flexibility in players of first person shooter games. Front. Psychol. 1, 1–5.
Karle, J. W., Watter, S., and Shedden, J. M. (2010). Task switching in video game players: benefits of selective attention but not resistance to proactive interference. Acta Psychol. (Amst.) 134, 70–78.