There appears to be correlations between the three Brain Styles and the three centers of the Enneagram model (The Researcher = Head, The Diplomat = Gut, The Poet = Heart).
Did Dr. Spiegel ever do in collaborative research/discussions with Dr. David N. Daniels (Enneagram Test Scientifically Validated | Dr. David N. Daniels) (1934-2017) when he was at Stanford?