Short-term Memory and Long-term Memory Flashcards
(21 cards)
What is memory?
The prcoess by which we retain information about past events
What is memory duration?
How long a memory lasts before it is no longer available
What is memory capacity?
How much information the memory can store
What is memory coding?
How information is processed in order to be stored by memory
What was the main study into duration of LTM? What were its aims and procedures?
Bahrick’s study
Aim: To investigate long term memory where the things to be remembered were of personal significance
Procedure:
1. Tested a group of 400 people of various ages (17-74)
2. Used two tests: a free recall test (names from graduating class) and a photo recognition test (50 photos from their yearbook and other photos, picking out students they went to school with)
What were the results of Bahrick’s study? What did these results help him conclude?
Free recall test:
* 60% accuracy (15 years after graduation)
* 30% accuracy (48 years after graduation)
Photo-recognition test:
* 90% accuracy (15 years after graduation)
* 70% accuracy (48 years after graduation)
Conclusion:
* People could remember certain information, e.g names and faces, for almost a lifetime
* These results support the multistore model and the idea our LTM has a lifetime duration (>48y)
What is the evaluation for the strength of Bahrick’s study?
High external validity
* High economic validity
* Real life meaningful memories were studied, like ones you would see in real life
* Recall rates were extremely low with random pictures
What is the evaluation for the weakness of Bahrick’s study?
Lack of control
* Natural experiment means there is less control than a lab
* Confounding variables cannot be controlled
* E.g participants may have looked at year book since school
What was the main study into STM? What were its aims and procedures?
Peterson and Peterson’s study
Aims:
* To investigate the duration of STM when verbal rehearsal was prevented
* Systematic and controlled lab experiment
Procedures:
1. 24 psychology students in a lab experiment
2. Given a nonsense trigram
3. Had to count backwards from a 3-digit number in 3s or 4s
4. Participants were then asked to recount the nonsense trigram
5. 2 practice trials and 8 real trials
6. TIme interval to count were either 3, 6, 9, 12, 15 or 18
What were the results of the Petersons’ study? What did this help them conclude?
- Information remains in STM for less than 18 seconds without verbal rehearsal
- Reinforces the multistore model and discrete components
- STM has a limited duration of ~18s
What is the evaluation for the strength of the Petersons’ study?
Highly controlled lab experiment
* Extraneous variables are controlled, and cause + effect pairs are established
* Eliminated other factors such as noise
* Standardised procedures make sure every participant takes the same test
* Scientific, so it can be replicated and checked
What is the evaluation for the weakness of Petersons’ study?
Low validity
* The participants were psychology students which would not represent the population
* Psychology students may have studied memory before and understood how to remember better
* Low ecological validity as nonsense trigrams are not seen in everyday life
What was the main study into capacity of STM? What were its aims and procedures?
Jacobs (1887)
Aims:
* See how much information can be held in STM before it is forgotten
Procedures:
1. Digit span technique
2. Participant is presented with a series of items, usually digits
3. Participant is required to repeat the sequence of items back in the same order. If the participant is correct, then the next line is read to them with an extra item
4. Continue until the participant makes a mistake
5. The maximum number repeated back is the capacity of their STM
What were the results of Jacobs’ test?
- Average span for digits was 9.3
- Average span for letters is 7.3
What was Miller’s review of STM?
- Article published states that the magic number for memory is 7±2
- Stated that we can hold 7±2 items in STM
- STM stores chunks of information rather than individual numbers or letters
- Capacity can be increased through chunking (converting a string of numbers into a number of larger, more memorable chunks)
- This increases capacity to an average of 7 chunks
What is the theorised capacity of LTM?
LTM is said to have an unlimited capacity as research has not been able to measure a finite amount
What are the evaluations for the weaknesses of the STM capacity study?
Capacity of STM may be more limited
* Miller’s original studies have not been replicated
* Cowan reviewed a variety of studies and concluded STM is limited to four chunks
* Visual information seemingly limited to four items
* This suggests STM may not be as expansive as previously thought
The size of the chunk matters
* The size of the chunk affects how many chunks you can remember
* Simon proved that people have a shorter memory span for larger than smaller chunks
* Supports the view that STM has a limited capacity and refines our understanding
Individual differences
* The capacity of STM is not the same for everyone
* Jacobs found that the recall increased steadily with age
* e.g 6 year olds remembered 6.6 words, 19 year olds remembered 8.6
* Age increase may be due to damages in brain capacity and/or the development of strategies such as chunking
What is the main study into memory coding? What were its aims and procedures?
Baddely’s study
Aims:
* Explores the effects of acoustic and semantic coding in STM/LTM
Procedures:
1. Participants were presented with a list of words in an independent design
2. LTM memory was tested by quizzing the participants 20 minutes after
What were the outcomes of Baddely’s study? What did these help him conclude?
STM:
* Acoustically similar has a 10% recall rate
* Others had 60-80% recall
LTM:
* Semantically similar has a 55% recall rate
* Others had 70-85% recall
Conclusion:
* Coding is acoustic in STM
* Coding is semantic in LTM
What is the evaluation for the strength of Baddely’s study?
Applications of the study
* Other cognitive psychologists built upon Baddley’s research
* Particularly with STM research, developing a brand new memory model known as working memory
* Applied to students’ revision. If LTM encodes semantically, mind maps make semantic links. Reading passages is acoustic and effective for STM, but ineffective for LTM
What is the evaluation for the weakness of Baddley’s study?
Articifical stimuli
* Stimuli are artificial rather than meaningful, and the word lists had no meaning to participants
* Caution needed when generalising findings to different types of memory tasks
* People may use semantic coding even for STM tasks to remember meaningful information
* This suggests that findings have a limited application
