 The elements of a secondarily automatic, complex movement are tightly fused. In contrast, those in a decomplex action or idea are more loosely associated (OM 1, prop. 12); this looseness makes it possible to include a repertoire of secondarily automatic movements in a variety of decomplex ones—the same notes in an endless number of tunes. Hartley also observes that people find it impossible to perform decomplex actions—play a tune, say a sentence—backward.