Memory

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  • Memory
    • Coding, Capacity and Duration of memory
      • Coding
        • Research: Baddeley (1966) gave different lists of words to remember. Group 1: Acoustically similar, Group 2: Acoustically dissimilar. Group 3: Semantically similar and Group 4: Semantically dissimilar
          • Procedure and findings: shown the original words and asked to recall them in the correct order, (STM recall) they tended to do worse with acoustically similar words.
            • 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.
      • Capacity
        • Digit Span
          • Joseph Jacobs 1887: Developed a technique to measure digit span. The researcher sees how many digits can be recalled in the correct order, slowly increasing until no more can be remembered. Mean span for for digits: 9.3, letters: 7.3
        • Span of memory and chunking
          • Span of memory and chunking: Miller made observations of everyday practice. Things come in 7s. Span of capacity of STM is about 7 items +- 2. Also noted that people can recall 5 words as well as 5 letters. They do this by chunking.
      • Duration
        • LTM:
          • Bahrick et al. 1975: studied 392 participant aged 17-74. Year books were obtained. Recall was tested by photo recognition of 50 photos and then recall of their graduating class.
            • Aged within 15 years of graduating = 90% in photo recognition , 48 years = 70%. Free recall was less good than photo recognition. after 15 years = 60%, dropping to 30% after 48 years. LTM can last a long time indeed
        • STM
          • STM: Peterson and Peterson 1959: tested 24 undergraduates. 8 trials. On each trial the student was given a trigram and a 3 digit number. They had to count backwards from the 3 digit number. They were told to stop at different times. 3,6,9,12,15 or 18 seconds.
            • Shows that STM may have a very short duration.
    • The multi-store model of memory
      • Atkinson and Shiffrin's model 1968
        • LTM
          • Maintenance rehearsal loop
          • Retrieval
    • Types of long-term memory
      • Semantic memory: A long-term memory store for our knowledge of what worlds and concepts mean. Need to be recalled deliberately.
      • Episodic memory: A long-term memory store for our knowledge of how to do things. This includes our memories of learned skills. Recall without making conscious or deliberate effort.
      • Procedural memory: A long term memory store for our knowledge of how to do things. Includes our memories of learned skills. We usually recall these memories without making a conscious or deliberate effort.
    • The working memory model
      • WMM: by Baddeley and Hitch (1974)  a  representation of short-term memory.
        • CE: coordinates the activities of the three subsystems in memory.
          • PL: processes information in terms of sound.
            • VSS: process the visual and spatial information in a mental space
              • EB: brings together material from the other subsystems into a single memory. Provides a bridge between WM and LTM
    • Explanations for Forgetting
      • Interference
        • Proactive interference: forgetting occurs when older memories, already stored, disrupt the recall of newer memories. Forgetting is greater when the memories are similar.
        • Retroactive interference: forgetting occurs when newer memories disrupt the recall of older memories already stored. Forgetting is more likely when the memories are similar.
      • Retrieval failure
        • Encoding specificity principle: Tulving (1983) received research into retrieval failure. He summarised the pattern found as the esp. This states that if a cue is available at encoding and at retrieval then it helps us remember.
        • Context dependent forgetting: Godden and Baddeley (1975), sea divers. Land - Land, Land - Underwater, Underwater- Underwater and Underwater- Land. Found that where they did not match accurate recall was 40% lower.
        • State- dependent forgetting: Carter and Cassaday (1998) gave anti- histamine drugs to their participants. Had to learn different words. Drug- drug, Drug - no drug, No drug- drug, and  no drug- no drug. Mismatch = much worse recall.
    • Factors affecting the accuracy of eyewitness testimony
      • Misleading information
        • Leading questions
          • Procedure: Loftus and Palmer (1974) got students to watch film clips of car accidents and then gave them questions about the accident. The critical question ( a leading question) was "About how fast were the cars going when they hit each other?".
            • Leading questions because hit describes the speed of the car. 5 groups, each was given a different verb: Hit, contacted, bumped, collided and smashed.
              • Findings: mean estimated speed was calculated. Contacted = 31.8 mph. Smashed= 40.5 mph.
        • Why do leading questions affect EWT?
          • The response- bias explanation suggests that the wording of the question has no real effect on the participants' memories but just how the decide to answer.
          • Substitution explanation: the wording of a leading question actually changes the participants memory of the film clip.
            • Loftus and Palmer (1974) conducted a second experiment that supported the substitution explanation. This was demonstratedbecause participants originally heard 'smashed' later were more likely to report seeing broken glass (there was none) than those who heard hit,
      • Anxiety
        • Negative effect on recall
          • Johnson and Scott (1976) led participants to believe that they were going to take part in a lab experiment. While seated they heard an argument. Then a man walked in with an greasy pen (low anxiety).
            • Other participants    heard the same argument but followed by the sound of breaking glass. The man walked out holding a paper knife covered in blood. (high anxiety condition)
              • Findings: picked out the man from a set of 50 photos, 49% of low anxiety identified him, 33% for high anxiety.
        • Positive effect on recall
          • Yuille and Cutshall (1986) did a study on a real life shooting in Vancouver. Shop owner shot a thief dead. 21 witnesses, 13 did the study. Interviews were held 4-5 months after. Accuracy was determined but detail and were asked to rate how stressed they felt, using a 7 point scale and asked if they had any emotional problems after the event.
            • Findings: the witnesses had very accurate in their accounts and there was little change in the amount of accuracy after 5 months. Some details were less accurate like colour of items, age, height , weight estimates. Those participants who reported the highest levels of stress were most accurate ( about 88% compared to 75% for the less stressed groups.)
    • Improving the accuracy of eyewitness testimony: Cognitive Interview
      • Fisher and Geiselman (1992): The cognitive interview is a method of interviewing to help them retrieve more accurate memories.     1) report everything      2) reinstate the context     3) reverse the order        4) change perspective
        • Fisher et al. (1987) developed some additional elemenst. For example the interviewer needs to establish eye contact and should know when to relinquish it. Also reduce anxiety, minimising distractions, witness to speak slowly and ask open- ended questions.

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