Cognitive

Cognitive

1. MEMORY: the process of retaining information about events that happened in the past

2. Capacity of memory

   • STM
     • Capacity: 7+/-2
       • Miller. AIM: test the capacity of STM. PROCEDURE: observed everyday things that come in sevens, (e.g. days in the week). Reviewed studies that have investigated the span of STM, (e.g. where participants count dots flashed on a screen or were tested on word recall). RESULTS: participants were accurate when 7 dots flashed, but not with 15. People can recall five words as well as they can five letters, they do this by chunking. CONCLUSION: capacity of STM is 7+/-2.
         • A problem is that Miller may have over estimated the capacity of STM. COWEN: capacity of STM is more liekly to be about four chunks, not seven chunks. VOGEL: found four tems was the limit for visual items. Means that the lower end of Miller's range is more appropriate.
         • Researchers have questioned the assumption that the chunk was the basic unit in STM, see it as vague. SIMON: found that the span as measured in chunks depends on the amount of information contained in the chunk. Larger chunks take up more space in STM.
         • When reading aloud the digit span increases. This is because the digits are also then stored briefly in the echoic store which strengthens the memory trace.
   • LTM
     • Infinite
   • Real world applications: the UK postcode system. BADDELEY: used chunking to make recommendations about what combinations of letters and numbers are easily remembered. Numbers best remembered if between city code and random letters. Phone numbers and car licence plates also use chunking. Shows that research on chunking has led to useful applications.
   • Jacobs. AIM: test our capacity of digits. PROCEDURE: participants heard fur digits, had to then say them in the right order. If correct they went to five digits and so on, until they got the order wrong. This determined their digit span. RESULTS: mean digit span was 9.3 and for letters it was 7.3. Digit span increased with age, for 8 year olds it was 6.6 digits, for 19 year olds it was 8.6 digits. May be as we develop strategies to improve digit span as we get older, like chunking.
     • A weakness is that it's very old as it was conducted in 1887. This means that it may not have adequately controlled the study as research wasn't formal. The instructions he used with adults and children may differed, acting as an EV. This may explain why adult performed better, rather than there being any real difference.

3. Duration of memory

   • STM
     • Duration: between 3 and 18 seconds
       • Peterson and Peterson. AIM: study the duration of STM. PROCEDURE: 24 students, each tested over eight trials. On each trial they were given a consonant syllable and a three digit number. Had to recall the consonant syllable after a retention interval of 3, 6, 9, 12, 15 or 18 seconds. Also had to count backwards from their three digit number during the retention interval. RESULTS: on average participants were 90% correct over 3 seconds, 2% correct after 18 seconds. CONCLUSION: STM has a very short duration, less that 18 seconds if verbal rehearsal is prevented.
         • Lacked ecological validity: stimulus material was artificial. Trying to memorise consonant syllables doesn't truly reflect most everyday memory tasks where what we're trying to remember is meaningful.
           • But , we remember meaningless things like groups of numbers in a phone number or post code. So it does have some relevance to everyday life.
         • An issue with the study is that the finding may be explained by displacement rather than spontaneous decay. Counting numbers in STM may have displaced the syllables.
           • Reitman: used auditory tones, not numbers to stop displacement. Duration of STM was longer than in the Petersons' study. Forgetting in the Petersons' study was likely to be due to displacement not decay.
         • It was a repeated measures design meaning that order effects, practice effects and demand characteristics may all be present. Thus reducing the validity of the results, so the duration may be shorted or longer than stated.
   • LTM
     • Bahrick. AIM: test the duration of LTM. PROCEDURE: tested 400 people aged 17-74 on their memory of classmates. Tests included photo recognition of 50 photos from their high school yearbook, and free recall where they listed who they could remember from their graduating class. RESULTS: those tested within 15 years of graduation were 90% accurate in identifying faces, after 48 years this declined to 70%. Free recall was 60% after 15 years. after 48 years it was 30%. CONCLUSION: duration of LTM is long if the information isn't meaningless.
       • A weakness is that the results may be due to rehearsal, some participants may look in their yearbooks regularly, so that's why their recall is good. Rehearsal is acting as an EV. Means that Bahrick's findings lack validity.

4. Encoding

   • Baddeley. AIM: investigate encoding in STM and LTM. PROCEDURE: group A given acoustically similar words (e.g. cab, can , mad, max). Group B given acoustically dissimilar words (e.g. pit, few, cow, pen). Group C given semantically similar words (e.g. great, large, bin, huge).Group D given semantically dissimilar words (e.g. good, huge, hot). On each trial five words were read out, after and interval they were shown 10 words, then asked to pick the right five words and put them in the right order. RESULTS: when STM was tested, those with acoustically similar words had the lowest recall. When LTM was tested (interval of 20 minutes), those with semantically similar words had the lowest recall. CONCLUSION: words in STM are encoded acoustically. Words in LTM are encoded semantically.
     • A weakness with this study is that a quite artificial stimuli used. This means that we should be cautious about generalising the findings to different kinds of memory task. E.g. if people were processing meaningful information they may use semantic encoding even for STM tasks. Means that this study only tells us a limited amount about encoding in STM/LTM.
     • A weakness with this study is that the LTM memory task wasn't very long term, only 20 minutes. It's possible that different kinds of encoding processes are involved when information is stored over months and years. However, the study does clearly show there's a difference over time.
   • Brandimote. Participants used visual encoding in STM when given a visual task and were prevented from doing verbal rehearsal.
   • Frost. LTM is also linked to visual categories participants encoded items visually.

5. Mullti-store model

   • Research evidence supports the MSM showing the existence of STM and LTM as separate stores. BEARDSLEY: used brain scanning and found that the prefrontal cortex is active during STM but not LTM tasks. SQUIRE: used brain scanning and foundthat the hippocampus is active when LTM is engaged. Ths research shows that different areas of the brain are active when people are doing STM tasks or LTM tasks.
   • Another study that supports the MSM was the case study of HM. His hippocampi were removed which led to an inability to transfer STM to LTM. HM was still able to remember things that occurred prior to the operation, i.e. his long term memory wasn't affected by the operation. This shos there's a distinction between short and long term memories.
   • One criticism is that the MSM is a very simplified model of memory. STM can be further subdivided into verbal and visual stores, as suggested by the working memory model. Research has shown that LTM can be subdivided into different kinds of memory, including semantic, episodic and procedural memory (SCHACHTER). The MSM just has one STM store and one LTM store).
   • Transfer may be possible to LTM without rehearsal. CRAIK and TULVING: suggested that the processing was more important than the rehearsal. They found that deeper processing leads to enhanced memory.
   • The model was influential as it was one of the early models of memory. Atkinson and Shriffrin introduced the notion of processes between the stores, as well as the sensory store.
   • More rehearsal doesn't always mean transfer from STM to LTM. BEKERIAN and BADDELEY: found that people didn't recall the BBC radio wavelength changes even thougb they heard the information over 1000 times.

6. Working memory model

7. EWT

   • A legal term that refers to an account of an event they have witnessed
   • Misleading information
     • Loftus and Palmer (1). AIM: investigate the effects of misleading information on memory. PROCEDURE: 45 American college students, shown clips of traffic accidents, split into groups of 9. 'About how fast were the cars travelling when they <verb> each other?' Each group had a different verb: hit, smashed, collided, bumped or contacted. RESULTS: group given 'smashed' estimated the highest speed (40.8mph), group given 'contacted' estimated the lowest speed (31.8mph). CONCLUSION: post-event information (misleading information) can have a significan
       • This study lacked ecological validity as they were shown a video, so their responses aren't reflective of a real crash. Participants may be less serious than they would be if they witnessed an actual accident. YUILLE and CUTSHALL: participants saw a real life armed robbery. Interviews had misleading questions but recll of events were accurate after four months. Suggests that EWT in the real world may not always be inaccurate.
     • Loftus and Palmer (2). AIM: to see whether misleading information alters storage or retrieval. PROCEDURE: 150 American college students viewed a car accident, asked a question about the speed. Three groups with different verbs: smashed, hit and a control group with no question. A week later they were asked more questions, including if there was any broken glass. RESULTS: 'smashed' were more likely to remember the broken glass (there was none) than the other groups. Responses about the broken glass for the 'hit' and the control were similar. CONCLUSIONS: post event information affects initial storage.
   • Loftus and Palmer (3). AIM: see whether participants in experiment 2 gave an incorrect response because the leading questions were verbal

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