1. "The Performance Burden" If neural activity is found to differ between groups or conditions, you can't necessarily make inferences about differences in neural information processing - this could reflect behavioral differences alone. For example, if younger children perform worse than older children but also recruit a few different regions, those neural regions might be operating in exactly the same way across ages (e.g., processing errors) - there's just more errors in the younger group! Even with similar levels of performance there's the possibility that children of different ages are using different strategies, different amounts of mental effort, or are differentially reacting to the closed, loud, and claustrophobia-inducing space that is an fMRI scanner...4 Things to Keep in Mind When Reading fMRI Studies
(Image: fMRI one, a Creative Commons Attribution (2.0) image from twitchcraft's photostream)
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.