Whitehead describes causal efficacy as "the experience dominating the primitive living organisms, which have a sense for the fate from which they have emerged, and the fate towards which they go." It is, in other words, the sense of causal relations between entities, a feeling of being influenced and affected by the surrounding environment, unmediated by the senses. Presentational immediacy, on the other hand, is what is usually referred to as "pure sense perception", unmediated by any causal or symbolic interpretation, even unconscious interpretation. In other words, it is pure appearance, which may or may not be delusive (e.g. mistaking an image in a mirror for "the real thing").
How do the senses affect causal efficacy? (If the question is unanswerable, say "unanswerable")
unmediated by the senses