Human subjects (22) practiced a video game, an Atari Air Combat Maneuvering task, 10 trials a day for 15 days. The dependent variable was number of hits per trial (game). The group mean followed an increasing, negatively accelerated course. The group standard deviation increased slowly for the first 6 days and then followed a level course thereafter. The interday correlations showed clear superdiagonal form, with complete differential stabilization after day 6. A performance test battery for environmental research was discussed. The Air Combat Maneuvering task is an excellent prospect for such a battery.