A cognitive psychologist believes that recall of verbal material differs with level of processing. He divided his subjects into three groups. In the low-processing-group, participants read each word and were instructed to count the number of letters in the word. In the medium-processing-group, participants were asked to read each word and think of a word that rhymes with the given word. In the high-processing-group, participants were asked to read each word and try to use it in a sentence. If the researcher wants to know whether the three groups have different amounts of recall, what type of statistical test should be used