Memory

• Coding, capacity and duration of memory meanings

  STM = the limited-capacity memory store. Coding is mainly acoustic (sounds), capacity is between 5 and 9 items on average, duration is about 18 seconds.

  LTM = the permanent memory store. Coding is mainly semantic (meaning), it has unlimited capacity and can store memories up to a lifetime.

  Coding = the format in which information is stored in the various memory stores

  Capacity = the amount of information that can be held in a memory store

  Duration = the length of time information can be held in memory
• Research on Coding

  Baddeley (1966a,1966b) gave different lists of words to four groups of participants to remember:

  group 1: acoustically similar

  group 2: acoustically dissimilar

  group 3 : semantically similar

  group 4: semantically dissimilar

  Participants were shown the original words and asked to recall them in the correct order. When they did this task immediately, recalling from STM, they tended to do worse with acoustically similar words. When they recalled the word list after a time interval of 20 minutes, recalling from LTM, they did worse with the semantically similar words.
• findings for research on coding

  These findings suggest that information is coded acoustically in STM and semantically in LTM
• One strength of Baddeley's study is that it identified a clear difference between two memory stores.


  Later research showed that there are some expectations to Baddeley's findings. But the idea that STM uses mostly acoustic coding and LTM mostly semantic has stood the test of time.

  This was an important step in our understanding of the memory system, which led to the multi-store model.
• For example, the word lists had no personal meaning to participants. So Baddeley's findings may not tell us much about coding in different kinds of memory tasks, especially in everyday life. When processing more meaningful information, people may use semantic coding even for STM tasks. This suggests that the findings from this study have limited application.


  One limitation of Baddeley's study was that it used quite artificial stimuli rather than meaningful material
• Research on capacity (1) Digit span


  Jacobs (1887) found out by measuring digit span. For example, researcher reads out four digits and the participants recalls these out loud in the correct order. If this is correct the researcher reads out five digits and so on until the participant cannot recall the order correctly. This indicates the individual's digit span. Jacobs found that the mean span for digits across all participants was 9.3 items. The mean span for letters was 7.3
• Research on capacity (2) span of memory and chunking

  Miller (1956) made observations of everyday practice.For example, he noted that things come in 7's such as 7 deadly sins, 7 days a week etc. Miller thought that the span of STM is about 7 items, plus or minus 2. But he also noted that people can recall five words as easily as they can recall five letters. We do this by chunking- grouping stes of digits or letters into units or chunks
• One strength of Jacobs' study is that it has been replicated


  The study is a very old one and early research in psychology often lacked adequate controls.For example, some participants' digit spans might have been underestimated because they were distracted during testing. Despite this, Jacobs' findings have been confirmed by other, better controlled studies since e.g. Bopp and Verhaeghen 2005. This suggests that Jacobs' study is a valid test of digit span STM.
• One limitation of Miller's researach is that he may have overestimated STM capacity.


  Cowan (2001) reviewed other research and concluded that the capacity of STM is only about 4 (plus or minus 1) chunks. This suggests that the lower end of Miller's estimate is more appropriate than seven items
• Research on duration (1) Duration of STM

  Peterson and Peterson (1959) tested 24 students in 8 trials each. On each trial the student was given a consonant syllable to remember. They were also given a 3 digit number. The student counted backwards from this number until told to stop. The counting backwards was to prevent any mental rehearsal of the consonant syllable. On each trial they were told to stop after varying periods of time: 3, 6, 9, 12, 15 or 18 seconds.
• Research on duration (1) Duration of STM findings

  After 3 seconds, average recall was about 80% after 18 seconds it was about 3%. Peterson and Peterson's findings suggested that STM duration may be about 18 seconds, unless we repeat the information over and over.
• Research on duration (2) Duration of LTM

  Bahrick et al. (1975) studied 392 American participants aged between 17 and 74. High school yearbooks were obtained from the participants or directly from some schools. Recall was tested in various ways, including: (1) photo-recognition test consisting of 50 photos, some from the participants' high school yearbooks,(2) free recall test where participants recalled all names of their graduating class.
• Research on duration (2) Duration of LTM findings

  Participants tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 years, recall declining to about 70% for photo recognition. Free recall was less accurate than recognition-about 60% after 15 years, dropping to 30% after 48 years. This shows that LTM may last up to a lifetime for some material.
• One limitation of Peterson and Peterson's study is that the stimulus material was artificial.


  The study is not completely irrelevant because we do sometimes try to remember fairly meaningless material e.g phone numbers. Even so, recalling consonant syllables does not reflect most everyday memory activities where what we are trying to remember is meaningful. This means the study lacked external validity.
• One strength of Bahrick et al'.s study is that it has high external validity.


  This is because the researchers investigated meaningful memories such as people's names and faces. When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower (for example Shepard 1967). This suggests that Bahrick et al.'s findings reflect a more 'real' estimate of the duration of LTM.
• The multi-store model of memory

  Multi-store model (MSM)= A representation of how memory works in terms of three stores called the sensory register, STM and LTM. It also describes how information is transferred from one store to another, what makes some memories last and what makes some memories disappear.
• The multi-store model of memory

  Sensory register = the memory stores for each of our five senses, such as vision and hearing . Coding in the iconic sensory register is visual and in the echoic sensory register it is acoustic. The capacity of sensory registers is huge and information lasts for a very short time.
• The multi-store model

  Atkinson and Shiffrin's MSM describes how information flows through the memory system.The model suggests that memory is made up of three stores linked by processing.
• Sensory register

  All stimuli from the environment pass into the sensory register (SR). This part of memory comprises several registers (sensory memory stores), one for each of our five senses. Coding in each store is modality-specific. For example, the store coding for visual information is iconic memory and the store coding acoustically is echoic memory. There are other sensory stores for touch, taste, smell information.
• Sensory register (p2)

  Duration of material in the SRs is very brief-less than half a second. the SRs have a very high capacity, for example over one hundred million cells in one eye, each storing data. Information passes further into the memory system only if you pay attention to it.
• Short-term memory (STM)

  Information in STM is coded mainly acoustically and lasts about 18 seconds unless it is rehearsed, so STM is more of a temporary store. STM is a limited-capacity store, because it can only contain a certain number of 'things' before forgetting occurs. Maintenance rehearsal occurs when we repeat material to ourselves over and over again. We can keep the information in our STMs as long as we rehearse it. If we rehearse it long enough, it passes into LTM.
• Long-term memory

  This is the potentially permanent memory store for information that has been rehearsed for a prolonged time. We have already seen that LTMs are coded mostly semantically. Psychologists believe that its duration may be up to a lifetime. According to the MSM, when we want to recall information from LTM, it has to be transferred back into STM by a process called retrieval.
• One strength of the MSM is support from studies showing that STM and LTM are different

  For example, Baddeley found that we tend to mix up words that sound similar when we are using our STMs. But we mix up words that have the same meanings when we use our LTMs. Further support comes from the studies of capacity and duration. These studies clearly show that STM and LTM are separate and independent memory stores as claimed by the MSM.
• One limitation of the MSM is evidence of more than one STM store.

  Shallice and Warrington (1970) studied a client they referred to as KF who had a clinical memory disorder called amnesia. KF's STM for digits was very poor when they were read out loud to him. But his recall was much better when he read the digits to himself. Further studies of KF showed that there could even be another short-term store for non-verbal sounds. This evidence suggests that the MSM is wrong in claiming that there is just one STM store processing different types of information.
• Another limitation of the MSM is that prolonged rehearsal is not needed for transfer to LTM.


  According to the MSM, what matters about rehearsal is the amount of it-the more you rehearsal something, the more likely it is to transfer to LTM. This is prolonged rehearsal. But Craik and Watkins (1973) found that the type of rehearsal is more important than the amount. Elaborative rehearsal is needed for long-term storage. This occurs when you link the information to your existing knowledge, or you think about what it means.
• limitation-prolonged rehearsal is not needed for transfer to LTM findings

  This suggests that the MSM does not fully explain how long-term storage is achieved.
• Types of LTM

  Episodic memory

  Semantic memory

  Procedural memory
• Episodic memory


  a long-term memory store for personal events. It includes memories of when the events occurred and of the people, objects, places and behaviours involved. Memories from this store have to be retrieved consciously and with effort.
• Semantic memory


  A long-term memory store for our knowledge. This includes facts and our knowledge of what words and concepts mean. These memories usually also need to be recalled deliberately.
• Procedural memory


  A long-term memory store for our knowledge of how to do things. This includes our memories of learned skills. We usually recall these memories without making a conscious or deliberate effort.
• Types of long-term memory-research

  Tulving (1985) was one of the first cognitive psychologists to realise that the multi-store model's view of LTM was too simplistic and inflexible. Tulving proposed that there are in fact three LTM stores, containing quite different types of information.He called them episodic memory, semantic memory and procedural memory.
• Episodic memory-detailed

  refers to our ability to recall events from our lives. This has been linked to a diary, a record of personal experiences.One example is the breakfast you ate this morning and these memories are complex.
• Episodic memory- detailed(p1)

  First, they are 'time-stamped'- in other words you remember when they happened as well as what happened. Episodic memories also store information about how events relate to each other in time.
• Episodic memory-detailed (p2)

  Secondly, your memory of a single episode will include several elements, such as people and places, objects and behaviours. All of these memories are interwoven to produce into a single memory
• Episodic memory-detailed (p3)

  Third, you have to make a conscious method to recall episodic memories. You do this quickly, but you are still aware that you are searching for your memory of what happened.
• Semantic memory-Detailed (p1)

  This store contains our shared knowledge of the world. It has been likened to a combination of an encyclopaedia and a dictionary. So it includes knowledge of such things as e.g. how to apply for uni or what an orange tastes like or the meaning of words. Your semantic memory contains your knowledge of an impressive number of concepts such as 'animals', 'love', 'frozen'.
• Semantic memory - detailed (p2)

  These memories are not 'time-stamped'. Semantic knowledge is less personal and more about facts we all share. It contains an immense collection of material which, given its nature, is constantly being added to. According to Tulving. Its less valuable to distortion and forgetting that episodic memory
• Procedural memory - detailed

  This is our memory for actions and skills. We can recall these memories without conscious awareness or much effort.E.g. driving a car. Our ability to do this becomes automatic through practice. We change gear without having to recall how. These sort of skills we might even find hard to explain to someone else
• Types of LTM- one strength is evidence from the famous case studies of HM and wearing

  Episodic memory in both men was severely impaired due to brain damage. But their semantic memories were relatively unaffected. They still understood the meaning of words.E.g. HM could not recall stroking a dog half an hour earlier but he did not need to have the concept of 'dog' explained to him.
• Types of LTM- one strength is evidence from the famous case studies of HM and wearing. (p2)


  Their procedural memories were also intact. They both still knew how to walk and speak, and Wearing knew how to read music, sing and play the piano. This evidence supports Tulving's view that there are different memory stores in LTM - one store can be damaged but other stores are unaffected.