The following has been adapted from IB Psychology: A Student’s Guide
Evidence for MSM: Serial position effect (primacy and recency effects)
The serial position effect (aka primacy and recency effect) is a cognitive phenomenon whereby people tend to remember the first (primacy) and last (recency) items in a series. This provides evidence for the MSM: people tend to remember the first items because they have longer to rehearse the information and they may have paid more attention to it, so it has a higher probability of being transferred to the LTS. They tend to remember the most recent information because it is still in their STS. Information in the middle may be lost because of the limited capacity of the STS. This can be shown in Glanzer and Cuntiz’s famous study.
The Primacy and Recency Effect (Glanzer and Cunitz, 1966)
A common method used to investigate memory is using free recall. This is when participants are exposed to a list of words (e.g. listening to a tape recording of words read out) and they are then asked to write down in any order (free) as many words as they can remember (recall). Using this method, researchers detected a pattern: participants can remember words better when they appear at the beginning of a list and at the end of a list. This has been dubbed the serial position effect (aka the primacy and recency effects).
Glanzer and Cunitz proposed that this was because the memories were coming from two different stores – the STS and the LTS. In order to demonstrate this, they conducted a series of experiments involving memory tests.
One of these experiments used 46 enlisted army men who were shown word monosyllabic words from the Thorndike-Lorge list on a screen using a projector. The experimenter read the words as they appeared also. The researchers used a repeated measures design by testing subjects individually and randomly assigning the word lists to one of the three conditions. The three conditions were:
- Immediate Free Recall Condition (IFR): wrote words down immediately after hearing them
- Delayed Free Recall Condition (DRF) – 10 seconds: wrote words down after a delay of 10 seconds.
- Delayed Free Recall Condition (DRF) – 30 seconds: wrote words down after a delay of 30 seconds.
Like Peterson and Peterson’s study, participants had a distraction task during the delay and had to count backwards in 3s to prevent further rehearsal.
The results showed that when there was no delay in recall (IFR) the primacy and recency effect was demonstrated as per usual. (Re-read above to see how this supports the MSM).
However, in the DFR-30 group only the primacy effect was present and the longer the delay, the more reduced was the recency effect (see graph below). This is further support for the MSM because it shows that the rehearsal has not changed the transfer to the LTS (because the primacy effect still exists), but the recency effect has gone because there was no time for rehearsal (because of the distraction task) and the 30 second delay was longer than the short-term stores capacity so the memories decayed (were lost).
It’s interesting to note that these experiments were conducted before Atkinson and Shiffrin proposed the MSM, so these experiments may have inspired the theory, not the other way around.
Glanzer, Murray, and Anita R. Cunitz. “Two Storage Mechanisms in Free Recall.” Journal of Verbal Learning and Verbal Behavior 5.4 (1966): 351-60. Web. (Link to full study)