I read this post and had to ask myself the question "What does this mean?" Is it about excitabilty?....I have a form of ADHD considered "Predominately Inattentive" which, I guess a type "B" personality would possibly encompass??? BTW, I'm new here and want to say 'Hi!' although I've been a PsychCentral reader for several years. I learned of my ADHD when I was 48 after trying to cram 12 credits into 1 semester. A big mistake on my part! I'm now taking Concerta for this and have seen some benefits. Yesterday, when I signed up.....that was all she wrote for me...I went on to something else.....sorry