I was recently involved in a project where I needed to examine some research literature on learning and memory. In particular, I was investigating the spaced learning effect on memory. Memory research has been central to psychology for as long as psychology has existed as an academic discipline, and the spacing effect (also known as distributed practice) has been studied for well over an hundred years. Studies of the spacing effect have shown that when you space learning over separate learning intervals, long term retention is normally much higher compared with the equivalent amount of training from a single or “massed” session. This effect is robust across different time scales, different kinds of learning, and is even true across different species. Another effect, not quite as well studied, is the testing effect. Repeated testing over time is also beneficial for learning, mainly because testing involves effortful memory retrieval, which is advantageous for the formation of long term memories. (more…)