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STM: Coding, Capacity and DurationSTM: Coding,In short term memory (STM) it is widely accepted that the coding is mainly acoustic.? When a person is presented with a list of numbers and letters, they will try to hold them in STM by rehearsing them (verbally).? Rehearsal is a verbal process regardless of whether the list of items is presented acoustically (someone reads them out), or visually (on a sheet of paper). However, it is also recognised that visual coding does occur in STM, as does some semantic coding.Supporting evidence: Baddeley (1966) found that lists of words that sounded the same were harder to immediately recall in order than words that sounded dissimilar. The greater confusion shows that words tend to be coded acoustically,Examples of similar sounding words: man ban can fan panExamples of dissimilar sounding words: pit few cow pen dayAnswer the following: Baddeley Gave different lists of words to four groups of participants to remember.What type of experimental design is this?_________________________Acoustic means:___________Semantic means:____________Fill in the types of words givenGroup 1Acoustically similar Group 2Acoustically dissimilar Group 3Semantically similarGroup 4Semantically dissimilarResults- When asked to recall word list immediately (accessing the STM)- When asked to do a task which took 20 minutes before recalling (accessing the LTM)-This suggests Evaluation of Baddeley’s study- artificial stimuli________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________STM: CapacityHow much information can be held in STM is limited. Notwithstanding that there are differences in capacity depending on the type of information, it is universally agreed that people can hold about seven things in STM.Supporting evidence: Jacobs (1887) presented participants with random sequences of letters or digits and recorded their memory span, requiring them to repeat them back in the same order. (The pace was controlled at half second intervals using a metronome). He found that on average, 9.3 digits were correctly recalled in order, and 7.3 letters were recalled in correct order. Participants recalled more digits (9 items) than letters (7 items)Jacobs also found that capacity increased steadily with age; in one sample of school girls he found that 8 year olds remembered an average of 6.6 digits whereas for 19 year olds it was 8.6 digits.Miller (1956) found that not only could people recall about 7 individual items, but could also recall 7 chunk of information. Miller suggested that the capacity for STM is 7 ± 2 chunks (in other words, nearly all people can recall between 5 and 9 small chunks of information). However, more recent research that managed to eliminate the possibility of letters being passed to LTM, and has found that on average, only 3.87 items could be correctly recalled (Cowan et al, 2005; Mathy and Feldman, 2012) suggesting that in Jacobs’ and Miller’s research, some of the information had been rehearsed and passed to LTM, thus over exaggerating the capacity of STMAnswer the following questions: How was the capacity of STM of an individual decided?Average span for digit?Average span for letters?Difference in spans across ages?Are there individual differences?Why is it useful?Evaluation of Miller- not so many chunks______________________________________________________________________________________________________________________________________________________________________________________________This suggests______________________________________________________________________________________________________________________________________________________________________________________________STM: Duration How long information can stay in short-term memory ranges from a few seconds up to a minute, but for most of us, it is somewhere in between.Supporting evidence: Peterson and Peterson 1959 presented three consonants, known as trigrams (ex. VGH, JSK), to participants for varying short-periods of time (3, 6, 9, 12, 15 and 18 seconds). The researchers also asked participants to count backwards in threes from a random three digit number to supress rehearsal. It was found that correct recall diminished quickly the longer the delay. After just 3 seconds, 80% of trigrams were recalled; after 6 seconds, 50%; after 18 seconds, 3% of the trigrams were recalled. This demonstrates that without rehearsal, information is rapidly lost from STM.Draw a line graph to illustrate the results of Peterson and Peterson researchAnswer the following questions: What is a trigram?What were the time delays?What was the interference task? Why do it?What was the % recall after 3 and 18 seconds?What about the validity?Exam consolidation: Answer the following questions to test your learning of today’s contentQ1.?Research has suggested that the encoding and capacity of short-term memory are different from the encoding and capacity of long-term memory.Explain what is meant by coding. (Total 2 marks)Q2.?Describe one way in which psychologists have investigated the duration of short-term memory. In your answer, you should include details of stimulus materials used, what participants were asked to do and how duration was measured. (Total 4 marks)Q3.?(a)???Read the item and then answer the questions that follow.??A researcher investigating the multi-store model of memory tested short-term memory by reading out loud sequences of numbers that participants then had to repeat aloud immediately after presentation. The first sequence was made up of three numbers: for example, 8, 5, 2. Each participant was tested several times, and each time the length of the sequence was increased by adding another number.Use your knowledge of memory to explain the purpose of this research and the likely outcome (4)(b)??After the study was completed, the researcher decided to modify the study by using sequences of letters rather than numbers.Suggest one 4-letter sequence and one 5-letter sequence that the researcher could use. In the case of each sequence, give a justification for your choice. Use a different justification for each sequence. (Total 4 marks) ................
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