# Memory: models, processes and research

## Jacobs (1887): Capacity of STM

AIM: find out the capacity of STM

PROCEDURE: Participants were given standarised instructions, telling them to recall specific digits adn letters immediately in the correct order. If recalled correctly, they'd move on to a longer sequence of digits and letters - this would continue until the particiapnt could no longer accurately recall the sequence. The final sequence they raeched is called their "digit span".

FINDINGS: found that the average digit span was 9.3 and that the average letter span was 7.3

CONCLUSION: concluded that out STM has the capabilities to 'hold' 7+ / -2 (between 5 and 9) pieces of information

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## Peterson & Peterson (1959): Duration of STM

AIM: find out the duration of STM

PROCEDURE: Lab experiment where 24 pscyhology students were asked to recall trigrams (meaningless three-consonant syllables , e.g TGH). To prevent rehearsal and create an interval, participants were asked to count backwards in threes from any chosen number, these intervals lasted 3,6,9,12,15,18 seconds, in which then they were asked to recall the trigram

FINDINGS: The longer the interval, the less trigrams accurately recalled. Participants were able to recall 80% of trigrams after 3 seocnds, but less than 10% after 18 secodns.

CONCLUSION: STM ahs a limited duration when rehersal is prevented, it is thought information is lost due to trace decay. Results show that teh STM is different from LTM in terms of duration

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## Bahrick (1975): Capacity and Duration of LTM

AIM: find out duration and capacity of LTM

PROCEDURE: 392 graduates of up to 50 years from a US high school, were shown pcitures from their yearbook. Each participant was paced into the recall or the recognition group. The recognition group were given the names and told to match them to the pictures. Recall group were given the photos and were told to name them

FINDINGS: Recall group - 60% remembered if graduated up to 7 years prior, and less than 20% remembered if graduated up to 47 years prior. Recognition group - 90% recalled if graudated up to 15 years prior, adn 60% remmebered if graduated up to 47 years prior.

CONCLUSION: The capacity adn duration of the long-term memory is potentially unlimited and for a lifetime.

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## Baddeley (1966): Coding of STM and LTM

AIM: See whether the meory stores code semantically or acoustically

PROCEDURE: Presented 75 parrticipants with a list of 4 words. The 4 possible lists of words were;

• Acoustically Similar (e.g. mad, map, mat, cap, cat)
• Acoustically Dissimilar (e.g. pen, cow, day, pit, and, cog)
• Semantically Similar (e.g. tall, high, broad, wide, bag)
• Semantically Dissimilar (e.g. foul, thin, late, safe, and, strong)

To test coding of STM, participants were given the list with the words in the wrong order, and told to rearrange them back into the original order. To test coding of LTM, participants were given the list with the words in the wrong order, and then following a 20 minute interval doing another task (to avoid rehersal), they were told to rearrange them back into the original order.

FINDINGS: For STM, list A was recalled the worst (10%). For LTM, list C was recalled worst (55%)

CONCLUSION: LTM codes semantically beacuse semantically dissimilar words caused most confusion. STM codes acoustically, as acoustically similar words caused most confusion

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## Robbins (1996): Testing Central Executive

AIM: Study role of central executive

PROCEDURE: 20 chess players were given 10 seconds to remember 16 positions from a chess game. They were then given 2 tasks; generate random no. sequences, and to carry out articulary suppression tasks

FINDINGS: Letter generation - poor memory and performance, Articulary suppression task - good memory and performance.

CONCLUSION: Phonological loop plays a role n remembering chess positions, not central executive

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## Baddeley and Hitch (1977): Interference

AIM: Study inteference

PROCEDURE: Real life study, asked rugby players ton recall the names of teams they've recently played. Most players don't play all games, due to injury and suspensions, so for one player their last game may have been yesterday, but for another it could have been 2 months ago.

FINDINGS: Recall was not due to decay, but was related to the number of intervening games up until the interview.

CONCLUSION: Demonstarates that interference is a reason ofr forgetting in everyday life - external validity.

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## Henck & Schmit (2000): Retroactive Interference

AIM: Assess influence of retroactive interfeerernce

PROCEDURE:700 bnames rnasdomly selected from a database of 1700 former students of a primary school, they wwre sent a quewstionairre. 211 ppts responded (aged 11-79), they were given a map of the school neighbour, ofwhich the 48 street names were replaxced with numbers, they were told t recall as many as they coulds rememebr. Questrionaiire also gathyered how many times the poeple had moved house, where they had lived, how long for, and how often they visited the school neighbiurhood.

FINDINGS: The amount of retroactive interference experienced waa assessed by the number of times people had moved house. 25% had never moved, BUT one paticipant had moved 40times. Found a positive correleaiton- more times people had moved house, the more street names tehy forgot.

CONCLUSION:Suggests learning new street names when moving, makes recalling old street names harder to do. Supporting idea of retroactive interference.

EVALUATION: Extraneeous variables have confouunded teh results. Example - people who played out in teh streets when a child, will know the street names bertter than those that did not.

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## Postman (1960): Retroactive Interference

AIM: Study retroactive interference

PROCEDURE: Lab experiment - ppts split inot 2 groups. Both groups told to remember a list of paired words, e.g. jelly-moss, cat-tree. Group B were also asked to remember a list of paired words in  which the 2nd paired word was different from the first list, e.g. jellytime, cat-grass. Group A were not given teh second list to lkearn. Then all particiapmnts were asked tor ecall the paired words from teh first list.

FINDINGS: Group A were better at recalling the first list than Group B

CONCLUSION: Leanring items i the second list interfered wityh ppts ability to recallk first list. This is an example of retroactive interefrence

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## Carter and Cassaday (1998): Retrieval Failure

AIM: Study retrieval failure as an explantion of forgetting

PROCEDURE: Gave anti-histamines to ppts, making them drowsy. Meaning a specific physiological state was created from their normal state of being alert. Ppts split into 4 groups (matching and mismatching learning and recall states) and were asked to learn a list of words.

FINDINGS: Demonstarted that a mismatching of physiological states resulted in higher retreival failure

CONCLUSION: Increases reliabilityand provides strong empirical evidece of retrieval failure.

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## Loftus (1979): Effect of anxiety of EWT

AIM: See is anxiety affects accuracy

PROCEDURE: Ppts left in waiting area outside a lab, waiting for the 'real study' to start, whilst expereincing one of two conditions:

1. Ppts overheard a discussion in teh lab about equiptment failure, followed by a man leaving the lab holding a pen with grease all over his hands.

2.Ppts overheard argument in lab, with sound of breaking galss and crashing chairs, followed by a man leaving the lab carrying a paper knife and covered in blood.

FINDINGS: Ppts were later asked to identify the man from a set of 50 images. 49% correctly identified man holding PEN, but only 33% correctly idenftified man with bloodstained KNIFE.

CONCLUSION: Accuracy is affected by anxiety

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## Loftus & Palmer (1974): Effect of Misleading Info

AIM: Investigate impact of misleading of information

PROCEDURE: Arranged ppts to watch car accident clip. Then asked Qs aout the accident, including a critical question about the speed of the cars. There were 2 conditions.

1. Critical question - " About how fast were the cars going when they HIT eachother?"

2. Critical question - " About how fast were the cars going when they CONTACTED / BUMPED / COLLIDED / SMASHED?"

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## Loftus & Palmer (1974): Effect of Misleading Info

AIM: investigate impact of misleading info

PROCEDURE: 150 students were shown a short clip of a car driving through the countryside followed by 4 seconds of a multiple-car traffic accident. They were then asked Qs about what they saw. The IV was the type of question asked. There were 3 conditions.

1. Asked 50 students - "How fast were the cars going when they HIT eachother?", 2. Asked 50 students - "How fast were the cars going when they SMASHED eachother?",  3.Asked last 50 students no question - Control Group.

After a week, without rewatching the footage, were all asked 10 Qs inclu. CQ "Did you see any broken glass yes or no?" This was to measure the DV. There was NO broken glass in footage.

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## Gieselman (1985): Effect of Cognitive Interview

AIM: investigated effectiveness of cognitive interview

PROCEDURE: Ppts view a film of a violent crime. 2 days later they were intervied by a policeman using 1 of 3 methods.  1. Cognitive Interview,  2. Standard Interview by the LA Police Department,  3. Interview using hypnosis. Number of facts accurately recalled and the number of errors made were recorded.

FINDINGS: No. significant difference in number of errors of each method. The average number of correctly recalle facts were;

Method 1: 41.2

Method 2: 29.4

Method 3: 38.0

CONCLUSION: The cognitive interview leads to better memory of events, with witness able to recall more relevant information compared with a traditional interview method.

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