On singularities of primitive cohomology classes

Green and Griffiths have introduced several notions of singularities associated with normal functions, especially in connection with middledimensional primitive Hodge classes. In this paper, by using the more elementary aspects of the Decomposition Theorem, we define global and local singularities associated with primitive middle-dimensional cohomology classes, and by using the Relative Hard Lefschetz Theorem, we show that these singularities detect the global and local triviality of the primitive class.