Any of our readers who have studied education in college or graduate school may be familiar with the “primacy and recency” effect. This effect was first detected by our old friend Hermann Ebbinghaus who is, of course, most famous for his well-known forgetting curve. Ebbinghaus noticed that in a test of free recall of a serial list, learners tended to remember items at the beginning of the list (primacy) and items at the end of the list (recency) better than items in the middle of the list.
But, in our last blog post we showed evidence that learners tend to disengage from long videos after about five minutes. So, if they disengage after five minutes how can they remember what they learned at the end of the video? Doesn’t this contradict the primacy and recency effect? Actually it does.
So, was Ebbinghaus wrong? Yes and no. In his experiment he tested his learners soon after they were shown the list, so it’s likely they were just recalling the end of the list from working memory, which does not help if our goal is long-term retention.
In a 1985 study “Information Impact and Factors Affecting Recall” Ralph A. Burns presented 20 minutes of material to his students and then gave them a test of free recall afterwards. Here are the results (percent of material remembered):
As you can see there is a dramatic drop-off in recall after five minutes, a leveling off from 5 to 15 minutes and then another drop-off after 15 minutes.
Yet more confirmation of the “five minute” rule.