Methods of Memory Measurement

Because there are many distinct kinds of memory, no single experimental method is appropriate for studying all of them — a method well suited to measuring one type of memory may simply not work for another. Three major methods illustrate this.

Free Recall and Recognition are used mainly to measure memory for facts and episodes. In the free recall method, participants are given a set of words to memorise and, after some time, are asked to recall as many of them as possible, in any order; the more items a participant recalls, the better their memory is judged to be. Recognition works differently: instead of generating items from scratch, participants are shown the items they had originally memorised mixed together with new 'distracter' items they had never seen, and their task is simply to recognise which ones they had learned earlier. The greater the number of previously learned items correctly recognised, the better the memory.

The Sentence Verification Task is used to measure semantic memory specifically, since general knowledge is not tied to any particular time or place and is therefore not well suited to recall-based methods. In this task, participants are shown sentences and asked to judge, as quickly as possible, whether each one is true or false. The faster a participant responds, the better retained the underlying semantic knowledge is judged to be, since semantic memory embodies knowledge that essentially everyone shares and is not itself very susceptible to forgetting. …