The United States, we’re told, is increasingly a house divided. Conservatives and progressives are so alienated from each other that conversation is virtually impossible. But are we really as divided as we’re led to believe? The podcast “Hidden Brain” begins a new series about how we form our political beliefs with an interview with UNC-Chapel Hill psychologist Kurt Gray, who studies how we think about our political allies and opponents — and how these insights can help us to chart a new path forward.