Memory Flashcards
What is memory?
Memory is the process by which we retain and recall information about events that have happened in the past.
What is coding?
The format in which information is stored in the memory stores. It’s the process of converting information from one format to another.
What is capacity?
The amount of information that can be stored.
What is duration?
The length of time information can be held in the memory store
According to Jacobs, what is the capacity of STM? How did he study this?
Jacobs (1887) developed a technique to measure digit span. The researcher gives, for example, four digits and then the participant is asked to recall these in the correct order out loud. If this is correct, the researcher reads out five digits, and so on until the participant cannot recall the order correctly. This determines 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.
According to Miller, what is the capacity of STM?
From a review of psychological research, Miller (1956) found that the span (capacity) of human memory is about 7 items (plus or minus 2). People cope well with counting 7 flashing dots but not much more – same for digits, numbers and even words. He also noted that people can recall 5 words as easily as 5 letters. They do this by chunking – grouping sets of letters or digits into units or chunks.
What is the capacity of LTM?
Potentially unlimited
Evaluate research into the capacity of memory in at least two ways
Jacobs - However, Jacobs’ study was conducted a long time ago. Early research in Psychology often lacked adequate control. For example, some participants may have been distracted while they were being tested so they didn’t perform as well as they might. This would mean that the results might not be valid because there were confounding variables that weren’t controlled. Therefore, we can’t be certain that the results are a valid reflection of the capacity of STM. However, the results have been supported in other research, supporting its validity.
Miller - However, he may have overestimated the capacity of STM. Cowan (2001) reviewed other research and concluded that the capacity of STM was only about four chunks. This suggests that the lower end of Miller’s estimate (5 items) is more appropriate than 7 items.
What did Peterson and Peterson do and find?
Aim: To investigate the duration of short-term memory and provide empirical evidence for the multi-store model.
Procedure: A lab experiment was conducted in which 24 undergraduate students took part in 8 trials (8 tests). On each trial they were given a consonant syllable or trigram (meaningless three-consonant syllables, e.g. TGH) to remember and a three-digit number. The student was then asked to count backwards from the number in either 3s or 4s until told to stop. The counting backwards was to prevent any mental rehearsal of the consonant syllable (which would increase the student’s memory). On each trial, they were told to stop after a different amount of time - 3, 6, 9, 12, 15 or 18 seconds. This is called a retention interval. After this, they were asked to stop counting and to repeat the trigram. The percentage of trigrams correctly recalled was recorded for each retention interval.
Findings: The longer the interval delay the less trigrams were recalled. Participants were able to recall 80% of trigrams after a 3 seconds delay. However, after 18 seconds less than 10% of trigrams were recalled correctly.
What did Peterson and Peterson conclude the duration of STM is?
Information must be rehearsed in order to keep it in STM. Short-term memory has a limited duration (up to 18 seconds) but in the exam we can say up to 30 seconds, when rehearsal is prevented. The results of the study also show the short-term memory is different from long-term memory in terms of duration.
What did Bahrick et al. do and find?
Aim: To investigate the duration of LTM.
Procedure: Participants were an opportunity sample of 392 American ex-high school students aged 17-74 years. High school yearbooks were obtained from the participants directly or from some schools. Recall was tested in various ways, including: (1) free recall test - where participants recalled the names of as many of their former classmates as possible; (2) photo recognition test - where they were asked to identify former classmates in a set of 50 where some were from their yearbook and some weren’t.
Findings: Participants who were tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 years, recall declined to about 70% for photo recognition. Free recall was less good. After 15 years, this was about 60% accurate, dropping to 30% after 48 years.
What did they conclude the duration of LTM is?
LTM has a seemingly unlimited duration.
Evaluate research into the duration of memory in at least two ways
Peterson and Peterson - a limitation of this is that the stimulus material was artificial. Trying to memorise consonant syllables does not reflect most real-life memory activities where what we are trying to remember is meaningful. So we might say that the study lacked external validity and may therefore underestimate the duration of STM for more realistic information. However, we do sometimes try to memorise fairly meaningless things e.g. phone numbers, so the study is not totally irrelevant and may tell us something about the duration of STM in these circumstances.
Bahrick et al - this study has higher external validity as real-life memories were studied. When studies on LTM have used meaningless pictures, recall rates were lower. Therefore the study seems to tell us about the duration of LTM with realistic tasks. The downside of such real-life research is that confounding variables are not controlled e.g. participants may have looked at their yearbook photos and rehearsed their memory over the years. Therefore, the study lacks internal validity and we can’t be certain that the results reflect the true duration of LTM without rehearsal.
How did Baddeley study the coding of STM and LTM? What did he find?
Baddeley (1966) gave different lists of words to four groups of participants to remember:
Group 1 – acoustically similar – words that sounded similar e.g. cat, cab, can
Group 2 – acoustically dissimilar – words that sounded different e.g. pit, few, cow
Group 3 – semantically similar – words with similar meanings e.g. great, large, big
Group 4 – semantically dissimilar – words with different meanings e.g. good, huge, hot
Participants were shown the original list of words and asked to recall them in the correct order. When they had to do this recall task immediately after hearing it (STM recall), they tended to do worse with acoustically similar words. This suggests that information is coded acoustically in STM.
If participants were asked to recall the word list after a time interval of 20 minutes (LTM recall), they did worse with the semantically similar words. This suggests that information is coded semantically in LTM.
What did he conclude about the coding of STM and LTM?
STM is coded acoustically
LMT is coded semantically
Evaluate research into the coding of memory in (just Baddeley)
The study used quite artificial stimuli rather than meaningful material. The word lists had no personal meaning to participants. This means that we should be cautious about generalising the findings to different kinds of memory task e.g. 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 about the coding of STM and LTM.
What is the Multi-Store Model of Memory (MSM)?
A structural model (representation) of memory. It was the first complex model of human memory. They suggest that each store is different/separate (unitary) and information is transferred from one store to another in a fixed, linear sequence.
What is meant by a unitary store and how many are there according to the MSM?
It means different or seperate. The MSM is made up of three
What is the sensory register?
The sensory register is the memory stores for each of our five senses e.g. iconic store for visual information, echoic store for sound information.
What is the coding, capacity and duration of the sensory register?
Coding - each store of the sensory register are coded differently (iconic coded visually, echoic coded acoustically etc.).
Capacity - high capacity e.g. over one hundred million cells in one eye
Duration - less than half a second
According to the MSM, how is information transferred from the sensory register to STM?
If you pay attention to it
According to the MSM, how is information transferred from STM to LTM?
Prolonged rehearsal
According to the MSM, how is information transferred from LTM to STM?
Retrieval
What are the strengths of the MSM?
Supporting evidence from previous studies
Supporting evidence - Baddeley’s study - supports that STM and LTM are coded differently which supports that they are unitary
Supporting evidence - Peterson and Peterson found that duration of STM is up to 30 seconds without rehersal and Bahrick et al. Found that the duration of LTM is up to a lifetime which supports that they are unitary (separate)