Two recent studies re: attention. The first involves auditory attention. If you're not paying attention to a lecture, it probably your parietal lobes more than your frontal executive.
This doesn't jive with a simple frontal model for ADD or ADHD of course. It also suggests a simple GO- NO GO task (motor inhibition) is not a great model for understanding attention (at least auditory) problems.
The second study here finds that the working memory difficulties associated with normal aging are more due to problems inhibiting distractions than true losses of memory. This is good news. This means controlling one's environment and distractions will improve one's memory efficiency. So look for some peace and quiet, and do one thing at a time.
Auditory Attention and fMRI