Textbooks make claims like this: "studies have shown that participants subliminally primed with a word (e.g., ‘beach’) will more quickly recognise words semantically related to it (e.g., ‘sand’), even though they never consciously registered the prime." Why should you believe such a claim.
Marcel, A. J. (1983). Conscious and unconscious perception: Experiments on visual masking and word recognition. Cognitive Psychology, 15, 197–237.