A major challenge for elementary school students is memorizing the multiplication table. This is difficult because there are many facts to learn and they are similar to each other, which creates proactive interference in memory. Here, we examined whether reducing interference would improve the memorization of the multiplication table by first graders. In a series of 16 short training sessions over a period of 4 weeks, each child learned 16 multiplication facts – 4 facts per week. Learning was better when the 4 facts in a given week were dissimilar from each other, a situation that reduces the proactive interference among them. Critically, this similarity effect originated in the specific learning context, i.e., the grouping of facts to weeks, and could not be explained as an intrinsic advantage of some facts over others. The similarity effect persisted 5 weeks after the end of the training period, i.e., proactive interference affected the long-term memory. Furthermore, during training, the similarity effect was not observed immediately but only in later training sessions, and only when examined in the beginning of a session. This indicates that proactive interference affected the long-term memory directly – it did not originate in short-term memory processes and then “leak” to long-term memory. We propose that the effectivity of this low-interference training method, which is dramatically different from currently-used pedagogical methods, calls for a serious reconsideration of the way we teach the multiplication table in school.
Does exposure to GSM 900 MHz mobile phone radiation affect short-term memory of elementary school students?