I guess it depends how you view/define learning. If by learning we mean learning _any_ information, then it seems likely the rate of learning would always incr

I guess it depends how you view/define learning. If by learning we mean learning _any_ information, then it seems likely the rate of learning would always increase over time since as you gain more knowledge it's more likely that you've done something similar in the past. If we're strictly talking about learning _new_ information (As in, not closely related to previous knowledge) then I can understand the argument that someone learns slower as they age. Basically it seems like it comes down to crystalized knowledge and how you count that.