Serial Position Effect

You go to the supermarket and realise you've left your list at home. You can't go back, so you have to do the best that you can. Typically most people will be able to remember what they wrote at the start or the end of the list; this is a widely researched phenomenon known as the serial position effect. Murdock investigated the phenomenon in 1962.

• Before we learn about the study, we will start with learning the serial position effect definition in psychology and cover a serial position effect definition psychology example to help you understand what precisely the Murdock 1962 serial position effect theory is.
• We will then move on to the study and begin with understanding Murdock's serial position curve study aims and the procedure.
• And finally, we will discuss Murdock's serial position curve study results and evaluate the strengths and weaknesses of the study.

Fig. 1. Murdock's (1962) serial position effect study provides evidence for Atkison and Shiffrin's (1968) MSM.

Murdock 1962 Serial Position Effect

Murdock was not the first psychologist to investigate factors that affected the accuracy of memory recall.

Murdock was a psychologist who attempted to investigate the serial position effect empirically.

Serial Position Effect Definition Psychology

The serial position effect theory is that the order of words and information learned impacts how likely we are to recall these from memory later. Murdock proposed that there are primacy and recency effects in our memory.

The definition of the primacy and recency effects that Murdock proposed are as follows:

Therefore, according to the serial position effect, we are less likely to recall (or recall accurately) the information learned in the middle. Let's look at an example and see if you can identify and understand the serial position effect definition.

Serial Position Effect Definition Psychology: Example

Below is a grocery list. According to Murdock's serial position effect, which items are you likely to recall?

If you thought bananas, apples and bread (primacy effect) and cheese, salad and plain flour (recency effect) were the answer, you'd be correct.

Murdock Serial Position Curve Study: Overview

Murdock's serial position curve study investigated whether the position of words in a list effect how likely the participant is to recall the words later.

The study investigated the serial position effect theory first proposed by Ebbinghaus.

Murdock's Serial Position Curve Study Aim

Now that we defined the serial position curve let's look at the study which found supporting evidence of the phenomenon.

Murdock's (1962) serial position effect study aimed to identify whether a word's position within a list affected recall accuracy.

Murdock's Serial Position Curve Study Method

Murdock recruited 16 participants of both genders to take part in the experiment. The participants were all enrolled on a psychology course in psychology.

The study took place in a lab setting and used standardised protocols. Standardising experiments allows others to replicate the study to measure its reliability easily. It also ensures that the participants are all tested with the exact instructions and in the same manner, increasing the study's internal reliability.

The procedure required participants to try and recall lists of words that ranged from 10 to 40 words. Each of the words in the list was visually presented for one second. Once each word was shown, participants were instructed to free recall them within 90 seconds.

The experiment was repeated with the same participants but with different words and different variations of list lengths over several days.

The lists included were common unrelated words (participants were unlikely to recall them due to forming associations between words).

Murdock's Serial Position Curve Study Results

The study found a trend in the results; no matter how long the list was or what the words were, participants were better at recalling the first few and last few words. The middle words within the list were often forgotten. These findings suggest that the position of words (the serial position) in a list affects the likelihood of later recall.

Figure 1 shows how the number of words recalled is highest for the beginning (primacy) and the end (recency) of a list but dips when recalling words in the middle.

Murdock's Serial Position Curve Study Conclusion

Murdock explained that the primacy effect results from elaborate rehearsal of earlier words allowing them to move into the long-term memory store (LTM). The recency effect theory can be explained as the words can be recalled as they remain in the short-term memory store (STM).

The thing you need to remember about the memory stores is that the STM has a limited capacity and duration, and information can pass through to the LTM store depending on elaborate rehearsal processes. The middle words in the list are likely forgotten because they were not elaborately rehearsed and so could not move to LTM and were displaced from the STM by later words in the list due to the store's limited capacity.

Murdock's Serial Position Curve Study Evaluation

Let's now explore the strengths and weaknesses of the serial position curve study.

Murdock's Serial Position Curve Study Strengths

• The study used a standardised procedure so the research could be easily replicated and assessed to measure its reliability. In addition, it ensures the study has high internal reliability as the same procedure was used for each participant.

• The study was conducted in a lab setting. In lab studies, researchers have a high level of control and can prevent extraneous variables from affecting the study's validity.

• The study is beneficial as it provided evidence that there are different stores for the different types of memory, which is what Atkinson and Shiffrin proposed in their multi-store memory model (1968).

• The procedure investigated whether the number of words within a list affected later recall concerning their position in the list. As the trend remained consistent despite more or fewer words in the list, it can be inferred that recall abilities are due to their position and not other factors, such as participants forming an association between words.

• Another strength of the study is that Glanzer and Cunitz (1966) found supporting evidence. Participants were split into two groups: group one was tasked with immediate recall, and group two with recall after 30 seconds, during which they completed a distraction task. Group one were better at recalling than group two. These results also further support that the recency effect results from the STM temporarily storing the words.

Murdock's Serial Position Curve Study Weaknesses

• The study was conducted in a lab and can be criticised for lacking mundane realism.

• The study recruited a non-representative sample. The study recruited psychology students, so they may have been able to guess the study's aims and act accordingly to the Hawthorne effect. Moreover, as the study used a small sample, it isn't easy to generalise the findings to the population.

• The study can be reductionist, as it over-simplifies memory by measuring the ability based on the accuracy of recalling a list of words. Different results may be found if we measure different types of memories, names or words with associations.

• Although the repeated measures design controlled for individual differences, which may be a potential extraneous variable that affects the study, it makes practice effects an issue. Over time, the participants may have gotten better at recalling words.