A scientist is researching the effects of a new supplement on memory improvements. They are comparing the effects of Supplement A and Supplement B (a placebo) on memory of list words. They want to measure the difference between scores on Day 1 and Day 2. They had participants memorise a list of words and complete a recall task where they write down as many words as they can remember. One day later the participants completed the same task after taking Supplement A or Supplement B.

What is the dependent variable in this example?