It's been 15 years, so I'm sure some has changed, but if I recall:
Hand eye coordination; time/distance calculations; pattern recognition...
But more, you then have the team exercises and individual aptitude tests which look at leadership skills, team working ability, problem solving, communication skills etc...
I think there was also some form of test in the bar at the OASC accommodation involving beer, a dodgy juke box with nothing but Elton John and Radiohead on it, and a crooked pool table with shrinking pockets...
