Our first cognitive psychology experiment

We are now well placed to run an actual psychology experiment. What we are going to do is measure memory for lists of letters. We are interested in the ability to remember a list of letters over a short amount of time. That is over the “short-term”. Some cognitive psychologists have argued that that the ability to retain these kinds of materials over the short- term depends on a particular memory system – known as short-term memory. Short-term memory is seen to be needed for the stuff that is of only temporary significance – did he just say turn right and then left or left and then right? Long-term memory is where you store enduring facts about the world.

H2O is the molecular structure of water. Paris is the capital of France. In this experiment each list contains six letters. In order to test memory for these kinds of materials we can adopt the following three-step procedure. Step 1 – Present each letter one at a time. Step 2 - Pause. Step 3 - Have the participant write down the letters in the order in which they were presented. These three steps map onto 3 stages in memory Step 1 – is known as Presentation. The letters to be remembered are read into or encoded into memory. Step 2 – is known as Retention. The stored letters are held in memory. Step 3 – is know as Test.

The stored letters are retrieved from memory. Presentation, Retention and Test. During the middle of the 20th century when this kind of experiment was first run, it was discovered that people were much better at remembering lists of letters in which the letters sounded different from one another than lists of letters in which the letters were similar in sound. H, I, J, L, M, O all sound different from each other P, V, B, C, D, E all sound similar to one another. Memory for the first kind of list was much better than that for the second. So the first kind of lists are known as phonologically dissimilar lists and the second as phonologically similar lists.

The term phonologically refers to the nature of the spoken form of the letters. The basic finding is that Phonologically dissimilar letter lists are recalled better than phonologically similar letter lists. This has come to be known as the phonological similarity effect. Of course the critical question is why does this happen. And cognitive psychologists are still engaged in tying down exactly why this happens. In our experiment we will be slightly less ambitious and just collect some data to see just how robust the phonological similarity effect is. But you may wonder does the effect arise during encoding, retention or recollection?