Dave: While researching an asignment, I spoke to Gemma Calvert (Reader in Cognitive Neuroscience, Department of Psychology, University of Bath) about this very point. She directed me to some papers by MairÃ©ad MacSweeney, who says “the left posterior perisylvian cortex is of fundamental importance to language processing, regardless of the modality in which it is conveyed.â€(MacSweeney et al, 2004)

I had known for some time that blind and sighted people map their worlds using the same areas of the brain (according to the research of John Geake), and now I had learned that the brain processes sign and spoken language in the same way, so I'm not convinced that learning sign will make it any easier to learn a spoken language.

However, I recognise that I have now taken this conversation deep into "anorak territory" where there be nobody but us geeks, so I shall cease and desist at this point ;-)