Memory

Memory

1. Multi-Store Model

   • Processes of encoding, storage and retrieval.
     • Information is detected by the sense organs and enters the sensory memory. If attended to this information enters the short term memory. Information from the STM is transferred to the long-term memory only if that information is rehearsed. Rehearsal was initially described by Atkinson and Shiffrin as maintenance rehearsal, but Shiffrin later suggested that rehearsal could be elaborative (Raaijmakers, & Shiffrin, 2003). If rehearsal does not occur, then information is forgotten, lost from short term memory through the processes of displacement or decay.
   • Sensory Memory
     • • Duration: ¼ to ½ second • Capacity: all sensory experience (v. larger capacity) • Encoding: sense specific (e.g. different stores for each sense)
   • Short Term Memory
     • • Duration: 0-18 seconds • Capacity: 7 +/- 2 items • Encoding: mainly auditory
   • Long Term Memory
     • • Duration: Unlimited • Capacity: Unlimited • Encoding: Mainly Semantic (but can be visual and auditory)
   • EVALUATION OF MSM
     • STRENGTH - Many memory studies provide evidence to support the distinction between STM and LTM (in terms of encoding, duration and capacity). The model can account for primacy & recency effects. The model is influential as it has generated a lot of research into memory. The model is supported by studies of amnesiacs: For example the HM case study. HM is still alive but has marked problems in long-term memory after brain surgery. He has remembered little of personal (death of mother and father) or public events ( Watergate , Vietnam War) that have occurred over the last 45 years. However his short-term memory remains intact.
     • WEAKNESS - The model is oversimplified, in particular when it suggests that both short-term and long-term memory each operate in a single, uniform fashion. We now know is this not the case. It has now become apparent that both short-term and long-term memory are more complicated that previously thought. For example, the Working Model of Memory proposed by Baddeley and Hitch (1974) showed that short term memory is more than just one simple unitary store and comprises different components (e.g. central executive, visuo-spatial etc.). In the case of long-term memory, it is unlikely that different kinds of knowledge, such as remembering how to play a computer game, the rules of subtraction and remembering what we did yesterday are all stored within a single, long-term memory store. Indeed different types of long-term memory have been identified, namely episodic (memories of events), procedural (knowledge of how to do things) and semantic (general knowledge). The model suggests
   • Studies
     • Loftus & Palmer (1974) Aim: To test their hypothesis that the language used in eyewitness testimony can alter memory.
       • Procedure: Forty-five American students formed an opportunity sample. This was a laboratory experiment with five conditions, only one of which was experienced by each participant (an independent measures experimental design). 7 films of traffic accidents, ranging in duration from 5 to 30 seconds, were presented in a random order to each group. After watching the film participants were asked to describe what had happened as if they were eyewitnesses. They were then asked specific questions, including the question “About how fast were the cars going when they (smashed / collided / bumped / hit / contacted) each other?” Thus, the IV was the wording of the question and the DV was the speed reported by the participants.
         • Findings: The estimated speed was affected by the verb used. The verb implied information about the speed, which systematically affected the participants’ memory of the accident. Participants who were asked the “smashed” question thought the cars were going faster than those who were asked the “hit” question. The participants in the “smashed” condition reported the highest speed estimate (40.8 mph), followed by “collided” (39.3 mph), “bumped” (38.1 mph), “hit” (34 mph), and “contacted” (31.8 mph) in descending order.
           • Conclusion: The results show that the verb conveyed an impression of the speed the car was travelling and this altered the participants' perceptions. In other words, eyewitness testimony might be biased by the way questions are asked after a crime is committed.
       • Experiment 2 - Procedure: 150 students were shown a one minute film which featured a car driving through the countryside followed by four seconds of a multiple traffic accident. Afterwards the students were questioned about the film. The independent variable was the type of question asked. It was manipulated by asking 50 students 'how fast were the car going when they hit each other?', another 50 'how fast were the car going when they smashed each other?', and the remaining 50 participants were not asked a question at all (i.e. the control group). One week later the dependent variable was measured - without seeing the film again they answered ten questions, one of which was a critical one randomly placed in the list: “Did you see any broken glass? Yes or no?" There was no broken glass on the original film.
         • Findings - Participants who were asked how fast the cars were going when they smashed were more likely to report seeing broken glass.
           • Conclusion: This research suggests that memory is easily distorted by questioning technique and information acquired after the event can merge with original memory causing inaccurate recall or reconstructive memory.
       • One limitation of the research is that it lacked mundane realism / ecological validity. Participants viewed video clips rather than being present at a real life accident. As the video clip does not have the same emotional impact as witnessing a real-life accident the participants would be less likely to pay attention and less motivated to be accurate in their judgements. A study conducted by Yuille and Cutshall (1986) conflicts the findings of this study. They found that misleading information did not alter the memory of people who had witnessed a real armed robbery. This implies that misleading information may have a greater influence in the lab rather and that Loftus and Palmer's study may have lacked ecological validity.
         • A further problem with the study was the use of students as participants. Students are not representative of the general population in a number of ways. Importantly they may be less experienced drivers and therefore less confident in their ability to estimate speeds. This may have influenced them to be more swayed by the verb in the question. A strength of the study is it's easy to replicate (i.e. copy). This is because the method was a laboratory experiment which followed a standardised procedure.

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