Memory Studies Flashcards
What did Jacob’s study research?
The capacity of STM by determining the individual’s digit span.
What were the results of Jacob’s (1887) study?
Jacobs found that the mean span for digits across all participants was 9.3 items. The mean span for letters was 7.3.
What was the method for Jacob’s (1887) research?
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.
Strengths of Jacob’s (1887) research
The results have been supported in other research, supporting its validity.
Weakness of Jacob’s (1887) research
Jacobs’ study was conducted a long time ago and early research in Psychology often lacked adequate control. E.g. 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.
What did Miller’s (1956) study research?
He researched the span (capacity) of human memory in items.
What was the method for Miller’s (1956) research?
Participants count and remember an increasing number of flashing dots, digits, numbers or words.
What were the results of Miller’s (1956) study?
Miller (1956) found that capacity of STM is 7 +- 2. People can recall 5 words as easily as 5 letters by chunking – grouping sets of letters or digits into units or chunks.
What were the weaknesses of Miller’s (1956) study?
He may have overestimated the capacity of STM as 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 was the aim of Peterson and Peterson (1959)
research?
To investigate the duration of short-term memory and provide empirical evidence for the multi-store model.
What was the procedure of Peterson and Peterson (1959) research?
A lab experiment with 8 trials.
1. On each trial they were given a meaningless consonant trigram (e.g. TGH) to remember and a three-digit number.
2. The student was then asked to count backwards from the number in either 3s or 4s until told to stop to prevent any mental rehearsal of the consonant syllable (which would increase the student’s memory).
3. On each trial, they were told to stop after a different amount of time - 3, 6, 9, 12, 15 or 18 seconds (a retention interval).
4. 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.
What was the sample of the Peterson and Peterson (1959) research?
24 undergraduate students
What were the findings of the Peterson and Peterson (1959) research?
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 conclusions were made from the findings of Peterson and Peterson’s (1959) research?
Information must be rehearsed in order to keep it in STM. Short-term memory has a limited duration (up to 18 seconds) when rehearsal is prevented. It also showed that short-term memory is different from long-term memory in terms of duration.
Weakness of Peterson and Peterson’s (1959) research.
The stimulus material was artificial as trying to memorise consonant syllables does not reflect most real-life memory activities where what we try to remember something meaningful. So we might say that the study lacked external validity and may therefore underestimates the duration of STM for more realistic information.
Strength (of weakness) of Peterson and Peterson’s (1959) research.
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.
What was the aim of Bahrick et al.’s (1975) study?
To investigate the duration of LTM.
What was the procedure of Bahrick et al.’s (1975) study?
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.
What was the sample of Bahrick et al.’s (1975) study?
nationality, number, type, age
Participants were an opportunity sample of 392 American ex-high school students aged 17-74 years.
What were the findings of Bahrick et al.’s (1975) study within 15 years of graduation?
Participants who were tested within 15 years of graduation were about 90% accurate in photo recognition. Free recall was less good. After 15 years, this was about 60% accurate.
What were the findings of Bahrick et al.’s (1975) study for 48 years after graduation?
Recall declined to about 70% for photo recognition. Free recall was less good, dropping to 30% after 48 years.
What was the conclusion of the findings of Bahrick et al.’s (1975) study?
LTM has a seemingly unlimited duration.
What were the strengths of Bahrick et al.’s (1975) study?
The 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.
What were the weaknesses of Bahrick et al.’s (1975) study?
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.
