CODING, CAPACITY AND DURATION OF MEMORY

WHAT IS CODING

Coding refers to the format or "type' of information which is stored in each memory store. Coding is acoustic in short-term memory, and semantic in long-term memory, as demonstrated by

What was Baddeley’s experiment on acoustic and semantic words

He found that more mistakes are made when recalling acoustically-similar words straight after learning them, whilst more mistakes are made when recalling semantically-similar words 20 minutes after learning them (LTM recall).

WHAT IS CAPACITY

Capacity refers to the volume of information/data which can be kept in any memory store at any one time.

What is the capacity of STM meant to be

The capacity of STM is thought to be 7 +/- 2 items (Miller)

What is the capacity of LTM meant to be

The capacity of LTM is unlimited.

What is the unlimited capacity of LTM based on

This is based on Miller's idea that things come in groups of 7 (e.g. 7 days of the week)

What does the unlimited capacity of LTM suggest

That we are predisposed to remembering this quantity and that such a 'chunking' method can help us recall information.

WHAT IS DURATION

the amount of time that information can be stored in each memory store.

What is the duration of STM

The duration of STM is 18-30 seconds,

Who demonstrated the duration of STM

Petersen et al (1959),

What did Petersen find

Increasing retention intervals decreased the accuracy of recall of consonant syllables in 24 undergraduates, when counting down from a 3 digit number (preventing mental rehearsal).

What is the duration of LTM

The duration of LTM is unlimited

Who showed that duration is unlimited

Bahrick et al (1975)

What did Bahrick find

Photo recognition of graduating classmates of 396 participants decreased from 90% to 70% between 15 years and 46 years of graduating.

WEAKNESS of research on coding capacity and duration in memory - BADDELY - low ecological validity

Much of the research on memory, such as studies by Baddeley (coding), Miller (capacity), and Peterson and Peterson (duration), relies on highly controlled laboratory settings that may not accurately reflect real-life memory use.

WEAKNESS OF CODING -BADDELY

Baddeley's study on acoustic and semantic coding in short-term and long-term memory uses artificial word lists, which might not mirror the types of information we encounter daily. This limits how we can generalize the findings to real-world memory processing.

What do these weaknesses highlight

These weaknesses highlight that while these studies provide valuable insights, the findings may not always translate to real-world memory performance.

WEAKNESS of capacity - MILLER

Capacity: Miller's famous finding of the "magic number 7" might not be applicable in everyday life, where our memory capacity may be influenced by factors like expertise, chunking, or individual differences that are not accounted for in the study.

WEAKNESS of duration

Peterson and Peterson's study on the duration of short-term memory uses meaningless trigrams, which may not represent the types of meaningful material people typically try to remember. This artificiality may reduce the relevance of the findings to everyday memory tasks.

WEAKNESS of Petersen

Conversely, the key issues with the Petersen et al and Miller et al studies is that they feature methodologies with low mundane realism, thus producing findings with little ecological validity. This is due to the use of artificial stimuli which has little personal meaning to the participants, and so does not accurately reflect everyday learning experiences. This therefore limits the generalisability of such findings.

WEAKNESS capacity - MILLER

More recent research has suggested that Miller may have over-exaggerated the capacity of STM, and that the capacity is more similar to 4 chunks as opposed to the original 5-9 limit. This may reflect the outdated methodologies adopted by Miller and specifically, the lack of control over confounding variables which may have contributed to this inaccurate estimate.

STRENGTH of Bahricks study - Use of meaningful stimuli and realism

• A strength of Bahrick et al's 1975 study is the use of meaningful stimuli, and a methodology which is high in mundane realism. This suggests that the findings have high ecological validity because they can be easily generalised to real-life, due to the stimuli reflecting those which we would often try to learn and recall in our day to day lives: information with personal and meaningtul value!

STRENGTH (CODING) - BADDELY - Showed info is coded acoustically in stm and semantically in lt,

Baddeley’s study showed that information is coded acoustically in short-term memory (STM) and semantically in long-term memory (LTM). The clarity of these findings supports the notion that different types of memory systems use different coding processes. This strengthens our understanding of memory systems and the processes involved.

STRENGTH (MILLER, CAPACITY)

• Miller (1956) found that the capacity of STM is around 7±2 items, which was a groundbreaking insight. This finding has been widely replicated, suggesting a consistent characteristic of STM’s capacity across different contexts. This provides a solid foundation for understanding how much information can be retained for short periods of time.

STRENGTH - Chunking

Miller also introduced the concept of "chunking," whereby individuals group information into larger, meaningful units to increase capacity. This is a practical insight into how the memory system works and how people can extend their memory capacity using strategies.

STRENGTH (DURATION) Peterson study

Peterson & Peterson’s study on the duration of STM showed that without rehearsal, memory decays quickly within 18 seconds, supporting the idea of limited duration in STM. On the other hand, Bahrick et al. (1975) showed that LTM can store information for many years, highlighting the long-lasting nature of LTM and providing empirical evidence of the differences in duration between STM and LTM.

Strength of Peterson - real life application

The understanding of memory duration has practical applications, such as in education, where repeated rehearsal can improve long-term retention. Similarly, the recognition that LTM can retain information over a lifetime provides insights into how memories form over time.