Chapter 1. Serial Position

1.1 Introduction

We all have to memorize lists of items. It might be the hardness scale in Geology or a list of vocabulary words in your language class. Sometimes it is important to remember the order of the items. The hardness scale has a very specific order. Sometimes the order does not matter, as with the vocabulary words, because you will use them in all sorts of order.

In this task you will be asked to memorize a list of words, but not the order in which the words are presented. At the end you will be asked to indicate which words were in the list. It is important to know that you can report the word you remember in any order.

1.2 Experiment Setup

1.3 Instructions

You will need to press the space bar to begin the experiment. At the beginning of each trial, a fixation mark will appear. Please look at this mark. After it is removed, you will see a list of words, with each word presented for a preset length of time. Your task will be to remember the words. At the end of the list, you will be asked to remember them immediately or after a delay. If there is a delay, you will be asked to perform a tracking task to distract you during the intervening period. A box and a dot will appear on the screen. Your task will be to use your mouse to move the box and to try to keep the dot inside of the square. Once this period is over, you will be shown a list of words. You should click on the words you had been shown previously.

You will be shown two lists.

1.4 Experiment

1.5 Results

1.6 Debriefing

The serial position effect is one of the classic findings in psychology. Think of the list being presented. When the first word has been presented, you only have one word to study. No other word in the list will have so much of your attention. No wonder you generally retrieve that word best in the list. As more words are presented, you have more words to try to remember. Gradually you reach the capacity of how many items you can hold in your short-term memory. But the first items in the list can still be retrieved; with only a few items you have a better chance of storing them in long-term memory. But for items than you have not seen until your short-term memory is full, they have never had as much of your attention and are much less likely to be stored in long-term memory. This is the standard explanation given for the primacy effect.

The recency effect is different. These words do not have the advantage of being studied in a small group, so why does the recency effect happen? It is because if you try you retrieve the most recent words first, they might still be present in the short-term memory. However, the recency effect is fragile. Trying to retrieve the last words after you have retrieved other words will mean that they have been replaced in short-term memory; similarly, if you create a delay between word presentation and retrieval, you should not get a recency effect.

The serial position has wide implications, the most commonly used being that you should always present the most important information first. One place where you see the serial position effect being taken advantage of is in the list of actors in a movie or television show. The star is always presented first.

References:

Calkins, M. W. (1896b). Association: An essay analytic and experimental. Psychological Review Monograph Supplements, 1(2), 1-56.

Madigan, S. & O’Hara, R. (1992). Short-term memory at the turn of the century: Mary Whiton Calkins's memory research, American Psychologist, 47(2), 170-174.

1.7 Quiz