Sensory Register:

The SR is where information from the senses (sight, sound, smell, touch and taste) is stored, but only for a duration of approximately half a second before it is forgotten.

• Duration: ¼ to ½ second
• Capacity: all sensory experience (very larger capacity)
• Coding: sense specific (e.g. different stores for each sense e.g. if you see something that is encoded by the sight sense, if you eat something that is encoded by the taste sense) The two main stores are echoic memory – sound that is coded acoustically, and iconic memory – visual information that is coded visually.

Key study for Coding of the Sensory Register:

Sperling (1960) presented students with a 3×4 grid which contained a mixture if letters and numbers. He asked participants to stare at a blue cross on a screen. The table of 12 letters and numbers flashed up for 50 milliseconds (a blink of an eye). They were then asked to write down as many of the letters and numbers as they could

The same participants were then shown a different table of letters and numbers, however this time after the grid had gone, the researcher called up ‘high’, ‘middle’ or ‘low’. Participants were required to recall only the letters in the row I specify.

Results:

Mean averages:

• Whole grid = 5/12 items recalled on average
• One Row = 3/4 items recalled on average

Theoretically participants should have been able to remember 4 items from a row, however approximately only 3 were remembered. This suggests that sensory memory cannot hold information for long, it decays rapidly in the sensory store: ¼ – ½ a second! This supports the existence of a sensory store!

Short-term Memory:

We don’t always pay attention to all of the information that is around us, therefore the info that is ignored would not move any further in the MSM. However, if attended to, sensory information moves into the STM for temporary storage, which will be encoded visually (as an image), acoustically (as a sound) or, less often, semantically (through its meaning).

STM is thought to have a capacity of 5-9 items and duration of approximately 30 seconds. This capacity can be increased through ‘chunking’, for example converting a string of items into a number of larger ‘chunks’. A good example is when we are trying to learn a mobile phone number: 01494324654, we may chunk the aerial code 01494, and then the rest of the number in chunks of three i.e. 324, 654.

• Duration: 18-30 seconds
• Capacity: 7 +/- 2 items – this means that the average capacity is 7, 5, or 9
• Coding: mainly acoustic

Rehearsing information via maintenance rehearsal (when we repeat the information to ourselves over and over again) helps to retain information in the STM, If we rehearse it for long enough it passes into LTM. If information is not rehearsed is forgotten and displaced after around 30 seconds. 

Key study for Duration of STM:

The duration of the short term memory was measured using the Peterson & Peterson (1959) technique. Participants were given trigrams which they had to recall after varying amounts of time from 0-18 seconds.

Examples of trigrams: TYF, GHW, SDT

They had to then do an interference task to prevent the participants from rehearsing. They did this by giving them a number that they had to count down from until they were told to stop. for example they could be given the number 56, and then have to count down, 55, 54, 53, 52 STOP!

Participants were asked to stop counting down after various amounts of time.

They found that only 10% of the trigrams were recalled after 18 seconds, this being the new, average duration of the short term memory, therefore our memories are very short lived according to Brown-Peterson.

Key study for Capacity of STM:

Key study for the Coding of STM:

The key study here can be used for STM and for LTM since it investigated both.

Baddeley (1966) Participants were given four sets of words to recall in order.  For the STM task they had to recall them immediately following presentation and for the LTM task they had to be recalled following a longer time interval.

• Set 1 were words that all sounded similar, for example: cat, mat, cap, map…
• Set 2 were words that sounded differently for example: dog, bin, cup, pen….
• Set 3 were words of similar meaning for example: big, large, huge, vast…
• Set 4 were words of different meaning for example: huge, good, light, blue….

The researchers then recorded how many mistakes were made in recalling the sets of words.

In the STM procedure participants made significantly more mistakes on words that sounded alike, so for example, would confuse cat and cap etc.  Similarly with letters, S and X would be confused as would M and N and P and B etc. It was concluded that in STM information is coded by its sound (acoustically) so when we recall information from STM similar sounding words get confused. It was concluded that in STM information is coded by its sound (acoustically) similar sounding words get easily confused whilst you try and rehearse them in your head.

Long-term Memory:

This is seen as a permanent memory store, something you ideally want for all the material in your Psychology A level course ;-). It is also theorised that information in the LTM is predominantly encoded semantically. This means you have an understanding of it and therefore it is remembered, they tend to be general facts and knowledge i.e. you understand that football is a sport, you understand how to calculate algebra because you understand the steps and the logically outcomes of each step.

• Duration: Unlimited
• Capacity: Unlimited
• Coding: Mainly Semantic (but can be visual and auditory)

It is important to note that when we recall info that is stored in LTM, it has to be transferred back to the STM by a process called retrieval. According to MSM, no memories can be directly recalled from the LTM.

Key study for the Coding of LTM:

Baddeley (1966) Participants were given four sets of words to recall in order.  For the STM task they had to recall them immediately following presentation and for the LTM task they had to be recalled following a longer time interval.

• Set 1 were words that all sounded similar, for example: cat, mat, cap, map…
• Set 2 were words that sounded differently for example: dog, bin, cup, pen….
• Set 3 were words of similar meaning for example: big, large, huge, vast…
• Set 4 were words of different meaning for example: huge, good, light, blue….

The researchers then recorded how many mistakes were made in recalling the sets of words.

In the LTM procedure participants recalled the information after 20 minutes. In this condition, participants were far more likely to confuse words of similar meaning replacing huge with vast or night and dark etc. It was concluded that in LTM information is encoded semantically e.g. our knowledge and understanding of the words. This is because participants would use their LTM memory by understanding that all the words were related to big. But they would struggle to recall it in the correct order because this would be utilizing the STM and therefore would be forgotten because the duration of STM is up to 18-30 seconds.

Evaluating Research in the MSM – Research: GRAVER

Weaknesses:

Here is an example of the MSM in action: 

Sensory Register: You are in a lesson listening to me blabber on about Psychology, you can see my PowerPoint on the board and you can hear my voice, these are encoded in the sight and sound stores.

Short-term Memory: You haven’t paid attention to all the information in my lesson and some of it goes in one ear and out the other, it is forgotten and displaced. However, when I start telling you a memory strategy on how to remember the ethics in Psychology, this helps you to chunk the information and helps you to remember it. You then go over PADDI WAC in your notes outside of lesson – maintenance rehearsal.

Long-term Memory:

When you return to my next lesson, I ask you to recall all of PADDI WAC, and you do this very successfully by transferring this memory into your STM. This is because you have a semantic understanding of the information and it is now a permanent memory.

https://www.youtube.com/watch?time_continue=49&v=3IJO5RBBK0I&feature=emb_title

Evaluation of the MSM – Theory: SAUNDERS 

Strengths:

• Supporting research: There is a large base of research that supports the idea of distinct STM and LTM systems as outlined in the MSM of memory e.g. Baddeley. The classic case is that of Henry Molaison (HM). When HM was 9 years old he was involved in a cycling accident. He recovered and appeared fine, until he stared having fits. This was diagnosed as epilepsy. HM was ridiculed and neglected by his family, as they believed that his fits and unusual behaviour brought shame on to the family. Medication was not working to resolve his condition and so, at the age of 27, he underwent surgery in an attempt to cure his epilepsy. A surgeon, William Scoville removed both his temporal lobes including a structure known as the hippocampus, and an area now known to be crucial to memory. He could remember some things — scenes from his childhood, some facts about his parents, and historical events that occurred before his surgery — but he was unable to form new memories. This case supported the MSM as, there were many attempts to move HM’s STM to his LTM, but it never happened. Therefore, there must be two different areas of the brain responsible for the STM and LTM.

• Supporting research – Baddeley, supports the MSM, because his study evidences a separation as it shows that STM is coded acoustic, whereas LTM is coded semantic.
• Usefulness – The MSM was a pioneering model of memory that inspired further research and consequently other influential models, such as the Working Memory Model by Baddeley and Hitch.

Weaknesses:

• Alternative explanation – Craik & Watkins disagree with the MSM’s belief that rehearsal is important in terms of how many times the info is rehearsed. They believed that this was too simplistic, and that the type of rehearsal was far more important. They found two different types of rehearsal; maintenance rehearsal as described in the MSM, but this doesn’t transfer info to the LTM, it simply maintains in it the STM, hence the name maintenance. However, elaborative rehearsal is needed in order for info to be processed into LTM. This is when you connect the information to your existing knowledge, or you think about what it means. For example, when we are learning new things in psychology, I may try to get you to think of examples of it in you own lives. This is because research suggests that it helps you to store this information in your LTM 🙂 This discredits the MSM because it is another research finding that cannot be explained by the MSM. This proves that this model may not be complex enough to fully explain memory.
• Reductionist – The model is arguably over-simplified, as evidence suggests that there are multiple short and long-term memory stores, e.g. ‘LTM’ can be split into Episodic, Procedural and Semantic memory, we will talk about this in more depth later on.

Support and Conflict:

• KF who suffered damage to his STM following a motorcycling accident still retained a near normal LTM.  Again this suggests two different memory stores, with STM and LTM being distinct. However, yet again the situation wasn’t quite that simple since KF could still recall visual information using his STM but struggled with auditory and verbal information, making conversation difficult.  This seems to suggest that STM is also more complex and may have further components.

We therefore have a situation were cases of amnesia can both support the idea of two memory stores whilst at the same time question the idea.  This is particularly good stuff to include in a discussion of the existence of two memory stores.