Memory: types of memory Flashcards
What are the 3 types of memory
- Sensory register
- Short-term memory (STM)
- Long-term memory (LTM)
What is the sensory register
- Temporarily stores info from senses -> constantly receives info from the environment.
- Unless you pay attention, this disappears quickly through spontaneous decay.
-> trace just fades. - Limited capacity and very limited duration.
- info is coded depending on the sense that has picked it up.
-> e.g. visual or auditory.
What is short-term memory (STM)
- STM has limited capacity and limited duration.
-> coding is usually acoustic (sound).
What is Long-term memory (LTM)
- has an unlimited capacity -> permanent -> coding usually semantic (the meaning of the info).
Types of info:
-> Episodic memory
-> Semantic memory
-> Procedural memory
What is episodic memory
- Info about the EVENTS experienced, e.g. a concert or restaurant visit.
-> Info of the time visit + place, emotions and what happened. - memories are declarative -> can be consciously recalled.
What is semantic memory
- stores facts + knowledge we learnt and can recall this consciously.
-> no detail about the time + place where you learnt the info, simply the knowledge.
What is procedural memory
- the knowledge of how to do things, e.g. walking, playing the piano.
-> can’t be consciously recalled.
List the key studies on the duration of memory
- Sperling (sensory register)
- Peterson + Peterson (duration of STM)
- Barhrick (very long-term memories VLTMs)
Explain Sperling’s study on duration of memory (Sensory register)
- Method: lab experiment, ppts shown grid with 3 rows of 4 letters for 0.5 secs.
- Results: When recalling whole grid, only managed to recall 4 or 5 letters on average.
-> when a particular row was indicated, participants recall average of 3 items no matter which row was selected. - Conclusion: Participants were able to recall 3 items from ANY row -> almost the whole grid was held in the sensory register.
-> couldn’t report the whole grid because the trace faded before they could finish recall.
Evaluate Sperling’s study on the duration of memory (sensory register)
(+) lab experiment, high control of variables and easy to replicate -> highly scientific.
(-) artificial setting -> lacks ecological validity.
-> results and the task does not represent what would happen in the real world.
Explain Peterson + Peterson’s study on the duration of STM
- Method: ppts were shown nonsense trigrams (3 random consonants, e.g. CVM).
-> Asked to recall after either 3, 6, 9, 12, 15 or 18 secs.
-> During the pause, were asked to count back a certain number -> this was an interference to prevent repeating letters internally (rehearsal). - Results: after 3 seconds, participants recall about 80% of the trigrams correctly.
-> after 18 seconds, only about 10% of the trigrams were recalled. - Conclusion: When rehearsed prevented, little can stay in the STM for longer than 18 secs.
Evaluate Peterson + Peterson’s study on the duration of STM
(+) Lab experiment = reliable results.
(-) Nonsense trigrams artificial -> lacks ecological validity.
-> meaningful / real-life memories may last longer in the STM.
(-) only one type of stimulus was used -> the duration may vary with the stimulus.
(-) ppts saw many trigrams -> can lead to confusion.
Explain Bahrick’s experiment on VLTMs (duration of memory)
- Method: 392 people were asked to list names of ex classmates (Free-recall test).
-> shown photos and were asked to recall names (photo-recognition test).
-> or given names and asked to match them to a photo (name-recognition test). - Results: Within 15 years, participants recognise 90% of names and faces -> 60% accurate on free recall.
- After 30 years -> free recall declined to 30% accuracy.
- Conclusion: evidence of VLTMs in ‘real-life’ setting.
- Recognition is better than recall, so there may be a huge store of info, but not always easy to access all of it.
-> About 40% accurate.
Evaluate Bahrick’s experiment on VLTMs (duration of memory)
(+) field experimented -> high ecological validity.
-> (-) however it is hard to control variables -> findings are less reliable.
(+) showed better results than other studies on LTM, this may be because meaningful info is stored better.
(-) Info could have been rehearsed (e.g. may still be in touch, talked to friends about their memories) which increases recall.
-> (-) results are not generalisable to other types of info in LTM.
List the key studies on the capacity of memory
- Jacobs (capacity of STM)
- Miller (capacity of STM)
Explain Jacobs experiment on capacity of STM
- Method: ppts were presented with a string of letters or digits.
- had to repeat them back in the same order.
-> the number of digits or letters increased until the participant failed to recall the sequence correctly. - Results: most times, ppts recalled about 9 digits and about 7 letters.
-> the capacity increased with age during childhood. - Conclusion: Based on a range of results -> STM has limited storage capacity of 5-9 items.
-> STM increased with age, possibly due to use of memory techniques such as chunking. - Digits are easier to remember (10 digits vs 26 letters).
Evaluate Jacobs experiment on the capacity of the STM
(-) research is artificial and lacks ecological validity.
(-) lacks meaningful info -> meaningful info could be recalled better -> showing STM to have an even greater capacity.
(-) previous sequences ppts recalled might have confused them on future trials.
Explain Miller’s research on the capacity of STM
1) reviewed research into capacity of STM -> people remembered about 7 items.
2) argued the capacity of STM is 7 + or -2, Miller’s magic number.’
3) suggested we use ‘chunking’ to combine individual letters or numbers into larger, meaningful units.
-> E.g. 2, 0, 0, 3, 1, 9, 8, 7 is about all the digits the STM can hold.
-> ‘Chunked’ into meaningful recent years of 2003 and 1987, makes this easier to remember.
- the STM is able to hold about 7 pieces of chunked info, increasing the STM’s capacity.
What is coding
- the way info is stored in memory.
- in the STM -> we keep info active by repeating it to ourselves -> this involves acoustic coding.
-> acoustic coding -> how info sounds.
-> semantic coding -> the meaning of info. - In the LTM -> coding is generally semantic.
Explain Baddeley’s study on coding in the STM and LTM (acoustic and semantic coding)
- Method: participants were given 4 sets of words:
-> were acoustically similar (e.g. man, med, mat).
-> acoustically dissimilar (pit, cow, bar).
-> Semantically similar (big, large, huge).
-> or semantically dissimilar (good, hot, pig). - the experiment used the independent groups design.
- asked to recall immediately or following 20 minute task.
- Results: had problems recalling acoustically similar words when recalling immediately (from the STM).
-> If recalling after an interval (from LTM), had problems with semantically similar words. - Conclusion: there was confusion between similar words which suggests LTM more likely relies on semantic coding and STM on acoustic coding.
Evaluate Baddeley’s study on coding in the STM and LTM
(-) lacks ecological validity.
-> Other LTM types (episodic, procedural) and other ways of coding (e.g. visual) which are not considered.
(-) independent groups design -> no control over ppt variables.
