This is one explanation that Hobbes gives. But he also gives the impression that the mechanism is different. It is not that the motion of a later sensation interferes with the motion of an earlier one, but that the earlier motions are obscured by later ones in the way that the light of a star is obscured by the light of the sun. Imagination and memory are the same thing. The apparent difference between them is semantic.
Memory is the perception that one has perceived.
Imagination is also the source of understanding, of which there are two kinds. In a general way, understanding is imagination caused by a voluntary sign. Contemporary linguists who believe that chimpanzees can use a finite number of signs to signal for food, and to express certain other things, would readily agree with Hobbes. But this kind of symbol manipulation is not the same as having a language.