You probably know the game: you put one hand on the table, the other person puts their hand on yours, then you put yours on theirs, they put theirs on yours (still following?) and as you put your hands on theirs, you try to give it a ‘gentle’ slap while they try to pull their hand away from the ‘stack’ when you are about to slap them.
You are, of course, trying to avoid the slap and pull your hand away as the other hand comes down. To win, you need a really good reaction time, to pull your hand away just about as the other hand is about to slap yours.
Not a game someone with a severe acquired brain injury would be expected to be able to play, never mind to be able to play terribly well. Because first, they would need to understand the purpose of the game, then they would need to be able to co-ordinate their hands and to be able to pile them up alternating with yours, and then they would need to be able to see yours coming down onto theirs, react quickly and pull their hand away as yours is about to slap theirs.
Mmmmhhh. That pre-conceptions was wrong… as are so many others.