Coding. capacity & duration

What is coding? AO1

The way in which info is changed & stored in memory

Coding - STM & LTM AO1

• Baddeley

• Participants were asked to recall a list of acoustic or semantic words

• They had to recall either the words immediately to test STM, or after a 20 minutes, to test LTM.

• Immediate recall was worse for acoustically similar words, indicating that STM relies on acoustic coding, as the similarity in sounds interfered with word storage.

• Delayed recall was worse for semantically similar words, suggesting that LTM relies on semantic coding, as the similarity in meaning disrupted the storage process.

What is capacity? AO1

The maximum amount of info that can be retained in memory

Capacity - STM AO1

• Jacobs

• Participants had to complete the digit span task where they had to immediately recall a sequence of numbers in the correct order

• Sequence length increased after each correct response

• Participants could recall on average 9.3 numbers and 7.3 letters.

• Miller

• Found ‘Magic Number’ 7±2

• Can be increased through chunking – grouping information into meaningful units.
  CAPACITY IS LIMITED

Capacity - LTM AO1

• Anokhin found capacity is unlimited

• Info may be lost due to decay & interfernce but losses don’t happen due to limitation of capacity

What is duration? AO1

How long a memory can be held for before it’s forgotten

Duration - STM AO1

•  Peterson & Peterson

• Ppts were asked to recall consonant trigrams after intervals (3,6,9,12,15 or 18 seconds) while doing a distraction task (counting backwards)

• After 3 seconds average accurate recall was 80%.

• After 18 seconds average accurate recall was less than 10%, showing STM has a duration of 18-30 seconds.

Duration - LTM AO1

• Bahrick et al

• Approx 400 ppts aged 17-74 years from USA.

• Ppts took part in a recognition test of naming classmates from a set of 50 photos from high school yearbooks and a free recall test, where they had to recall names from their graduating class without any prompts

• For the recognition test after 15yrs recall accuracy was 90% and after 48yrs recall accuracy was 70%. In the free recall test average accuracy after 15yrs was 60% and after 48yrs it was 30%

• Duration is unlimited & may last a lifetime
  

Badeley AO3

• P - lab experiment

• E - highly controlled environment & used standardised procedures. For example, all participants were given the same instructions, the same types of word lists, and the same recall tasks, meaning the procedure was consistent across conditions. This standardisation ensures that each participant had an equal experience, reducing the influence of extraneous variables such as differences in presentation or testing conditions. As a result, any differences in recall can be more confidently attributed to the type of coding used in memory (acoustic in STM and semantic in LTM) rather than inconsistencies in the method. Because the study can also be replicated to check for inconsistencies using the same standardised procedure, it strengthens the reliability of the finding

• T - increases internal validity & reliability of his theory that coding in the STM is acoustic & semantic in LTM

• P - lab experiment

• E - unnatural lab setting which used artificial tasks. For example, study required participants to learn and recall artificial word lists under highly controlled conditions, which is not representative of how memory is used in everyday life. In real-world situations, people are more likely to remember meaningful, contextual information rather than isolated words presented without any personal relevance. Because the task is so artificial, participants may also use strategies such as rehearsal or chunking that they would not normally rely on in natural settings, which can further distort the findings. This means that although the study has high internal validity, it may not accurately reflect how short-term and long-term memory coding operates in real-life situations.

• T - reduces ecological validity & findings may lack generalisability to everyday memory use, limiting the overall usefulness of the research in explaining real-world memory processes.

Miller AO3

• P - overestimated Magic number

• E - Miller concluded that the STM has a capacity of 7+-2, suggesting that it is limited. However, more recent research, such as Cowan (2001), suggests that the true capacity of STM is closer to around four items under more controlled conditions. This means Miller’s conclusion may not be an accurate reflection of actual memory limits, as later findings consistently show a smaller capacity than he proposed.

• T - research may have exaggerated how much information STM can hold at one time, which reduces the validity of his findings

Bahrick et al AO3

• P - meaningful tasks

• E - Bahrick tested participants’ ability to recognise and recall the names and faces of their former high school classmates, some of whom they had not seen for up to 48 years. This task closely reflects how memory is used in everyday life, as it involves personally meaningful information that participants had genuinely learned and experienced, rather than meaningless stimuli such as word lists or digits often used in lab studies. Because the memories were naturally formed over many years, the study avoids the problem of artificial learning conditions and is more representative of how long-term memory operates in the real world. As a result, the findings are more generalisable to everyday memory performance, showing that long-term memory can last for several decades under natural conditions.

• T - increases ecological validity, therefore we can apply Bahrick’s duration of the LTM being unlimited to real world contexts outside of lab settings

• P - confounding variables

• E - Although the study aimed to test long-term memory for faces and names over many years, participants may have been exposed to the material after leaving school, rather than relying solely on long-term memory. For example, some participants may have looked at old yearbooks, photographs, or social media posts, or may have discussed former classmates with others over the years. This means their ability to recognise or recall names and faces may not have been entirely due to their stored long-term memory, but instead influenced by later rehearsal of the information. As a result, it is difficult to be certain that the high levels of recognition reported in the study are purely a measure of long-term memory duration

• T - This weakens the validity of the conclusions. suggesting the study may overestimate the duration of the LTM