i think u need to know a bit. for example, say in PD JAmes the skull beneath the skin, two of the characters motives are money, which fits into the themes/context with the moral and social decay, ie that money is so important u might kill your step mother or cousin or childhood friend.
i don't think we havt know a hell of lot on it but since it was in your trials maybe we need to know a little... i hadn't thought of it really. good luck anyways!!! i say just know a little that fits into context and major themes in the play.