Further evidence against the existence of a short-term memory store comes from experiments involving continual distractor tasks. In 1974, Robert Bjork and William B. Whitten presented subjects with word pairs to be remembered; however, before and after each word pair, subjects had to do a simple multiplication task for 12 seconds. After the final word-pair, subjects had to do the multiplication distractor task for 20 seconds. In their results, Bjork and Whitten found that the recency effect (the increased probability of recall of the last items studied) and the primacy effect (the increased probability of recall of the first few items) still remained. These results would seem inconsistent with the idea of short-term memory as the distractor items would have taken the place of some of the word-pairs in the buffer, thereby weakening the associated strength of the items in long-term memory. Bjork and Whitten hypothesized that these results could be attributed to the memory processes at work for long-term memory retrieval versus short-term memory retrieval.