My apologies for the long silence. Life and family issues are taking my time at the moment.
We have been talking about finger tapping tests, such as DigiTap app a while ago, and I asked if anybody is using them. I have since had email from a colleague who says he uses it regularly, particularly when wanting to examine motor slowing or needing an indicator of a subtle weakness on one side. He uses norms from Spreen and Strauss, which he finds not to be ideal, but better than nothing. He feels that when using an iPad app people tends to get somewhat inflated scores, and tends to take notice only when both fingers are well below expectation (e.g. >1.5 SD), or if there is a big difference between fingers. Sounds to me like a good clinical rule of thumb.