Researchers say they've found another reason why video games are so hard to give up: They may help fulfill basic psychological needs.

In a study published in the January issue of Motivation and Emotion, investigators from the University of Rochester and Immersyve Inc. looked at what motivated 1,000 gamers to keep playing video games.

"We think there's a deeper theory than the fun of playing," lead investigator Richard Ryan, a motivational psychologist at Rochester, said in a prepared statement.

The gamers were divided into four groups, each asked to play different games. They answered questionnaires both before and after playing the games. The researchers used the questionnaires to look at the underlying motives and satisfactions that can spark players' interests and sustain them during play.

The researchers found that the games can provide opportunities for achievement, freedom and even a connection to other players. Those benefits trumped a shallow sense of fun, which doesn't keep gamers as interested. Players reported feeling the best when the games produced positive experiences and challenges that connected to what they knew in the real world.

"It's our contention that the psychological 'pull' of games is largely due to their capacity to engender feelings of autonomy, competence and relatedness," said Ryan. He believes that video games not only motivate further play but "also can be experienced as enhancing psychological wellness, at least short-term."

For the participants who played massively multiplayer online, or MMO, games -- which are capable of supporting hundreds of thousands of players simultaneously -- the need for relatedness emerged "as an important satisfaction that promotes a sense of presence, game enjoyment and an intention for future play," the researchers found.

Ryan pointed out that while not all video games are able to satisfy basic psychological needs, "those that do may be the best at keeping players coming back."