In a memory study, the experimenter reads the same list of words to two groups. She asks group A to count the letters in each word, and she asks group B to focus on the meaning of each word for a later memory quiz. During a recall test, participants in group B recall significantly more words than participants in group A. Memory researchers attribute this effect to differences ina) priming b) levels of encoding/processing c) proactive interference d) procedural/implicit memory e) episodic memory