Works exhibited at “Outliers and American Vanguard Art” at the National Gallery of Art in Washington, Jan. 28, 2018. “Outliers” is extensive — about 280 artworks by 84 artists — and represents some five years of meticulous research by Lynne Cooke, the senior curator for special projects in modern art at the National Gallery. (Justin T. Gellerson/The New York Times)