Coding, Capacity, and Duration of Memory PDF

**Coding \[1\], Capacity \[2\], Duration \[3\] of memory** \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-...

**Coding \[1\], Capacity \[2\], Duration \[3\] of memory** \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **KEY TERMS** **STM** - The limited-capacity memory store. In STM, coding is mainly acoustic (sounds), capacity is between 5 and 9 items on average, duration is about 18 seconds. **LTM** - The permanent memory store. In LTM, coding is mainly semantic (meaning), it has unlimited capacity and can store memories for up to a lifetime. **Coding** - The format in which information is stored in the various memory stores aka the process of converting information between different forms **Capacity** - The amount of information that can be held in a memory store. **Duration** - The length of time information can be held in memory. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **Research on coding** - Information is stored in memory in different forms, depending on the memory store Baddeley (1966a, 1966b) gave different lists of words to four groups of participants to remember: - Group 1 (acoustically similar): wards sounded similar (eg, cat, cab, can). - Group 2 (acoustically dissimilar); words sounded different (eg. pit, few, cow). - Group 3 (semantically similar words with similar meanings (eg great, large, big). - Group 4 (semantically dissimilar): words with different meanings (eg good, huge, hot). \-- Participants were shown the original words and asked to recall them in the correct order. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **Findings on Baddeley's study** - When they did this task immediately, recalling from STM, they tended to do worse with acoustically similar words - When they recalled the word list after a time interval of 20 minutes, recalling from LTM, they did worse with the semantically similar words - These findings suggest that information is coded acoustically in STM and semantically in LTM. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **Evaluation on coding** **SEPARATE MEMORY STORES** - One strength of Baddeley\'s study is that it identified a clear difference between two memory stores. - Later research showed that there are some exceptions to Baddeley\'s findings. But the idea that STM uses mostly acoustic coding and LTM mostly semantic has stood the test of time. - This was an important step in our understanding of the memory system, which led to the multi-store model. **ARTIFICIAL STIMULI** - One limitation of Baddeley\'s study was that it used quite artificial stimuli rather than meaningful material. - For example, the word lists had no personal meaning to participants. Meaning, Baddeley\'s findings may not tell us much about coding in different kinds of memory tasks, especially in everyday life. - When processing more meaningful information, people may use semantic coding even for STM tasks. - This suggests that the findings from this study have limited application. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **Research on capacity** **DIGIT SPAN PROCEDURE** - Jacobs (1887) researched capacity through measuring digit span. - Researcher reads out four digits and the participant recall these out loud in the correct order. - If correct, the researcher reads out five digits and so on until the participant cannot recall the order correctly - this indicates the individual\'s digit span. **DIGIT SPAN FINDINGS** - Jacobs found that the mean span for **digits** across all participants was 9.3 items. - The mean span for **letters** was 7.3. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **SPAN OF MEMORY AND CHUNKING: PROCEDURE** - Miller (1956) made observations of everyday practice. - He noted that things come in sevens: - seven notes on the musical scale - seven days of the week - seven deadly sins **SPAN OF MEMORY AND CHUNKING: FINDINGS** - Miller said capacity of STM = 7 items +/- 2 - He also noted that people can recall five words as easily as they can recall five letters - we do this by chunking (grouping sets of digits or letters into units **Evaluation on capacity** **A VALID STUDY** - One strength of Jacobs\' study is that it has been replicated - The study is a very old one and early research in psychology often lacked adequate controls - For example, some participants\' digit spans might have been underestimated because they were distracted during testing (confounding variable) - Despite this, Jacobs\' findings have been confirmed by other, better controlled studies since (e.g. Bopp and Verhaeghen 2005) - This suggests that Jacobs\' study is a valid test of digit span in STM **NOT SO MANY CHUNKS** - One limitation of Miller\'s research is that he may have overestimated STM capacity - Cowan (2001) reviewed other research and concluded that the capacity of STM is only about 4 +/- 1 chunks - This suggests that the lower end of Miller\'s estimate (five items) is more appropriate than seven items \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **Research on duration** **DURATION OF STM PROCEDURE** - Peterson x2 (1959) tested 24 students in eight trials each - On each trial the student was given a consonant syllable to remember - They were also given a 3-digit number - The student counted backwards from this number until told to stop **\[because I said so\]** - The counting backwards was to prevent any mental rehearsal of the consonant syllable (which would increase the duration of STM memory for the syllable). **DURATION OF STM FINDINGS** - On each trial they were told to stop after varying periods of time: 3, 6, 9, 12, 15 or 18 seconds (the retention interval) - After 3 seconds, average recall was about 80%, after 18 seconds it was about 3% - Peterson x2 findings suggested that STM duration may be about 18 seconds, unless we repeat the Information over and over (i.e., verbal rehearsal) \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **DURATION OF LTM PROCEDURE** - Bahrick et al. (1975) studied 392 American participants aged between 17 and 74 - High school yearbooks were obtained from the participants - Recall was tested in various ways: - \(1) photo-recognition test consisting of 50 photos, some from the participants\' high school yearbooks - \(2) free recall test where participants recalled all the names of their graduating class. **DURATION OF LTM FINDINGS** - Participants tested within 15 years of graduation were about 90% accurate in photo recognition - After 48 years, recall declined to about 70% for photo recognition - Free recall was less accurate than recognition-about 60% after 15 years, dropping to 30% after 48 years - This shows that LTM may last up to a lifetime for some material. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- **Evaluation on duration** **MEANINGLESS STIMULI IN STM STUDY** - One limitation of Peterson x2 study is that the stimulus material was artificial - The study is not irrelevant because we do sometimes try to remember fairly meaningless material (e.g., phone numbers) - Even so, recalling consonant syllables does not reflect most everyday memory activities where what we are trying to remember is meaningful - This means the study lacked external validity **HIGH EXTERNAL VALIDITY** - One strength of Bahrick et al\'s study is that it has high external validity - This is because the researchers investigated meaningful memories (i.e., of people\'s names and faces) - When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower (eg Shepard 1967) - This suggests that Bahrick et al\'s findings reflect a more \'real\' estimate of the duration of LTM. **QUESTIONS:** 1\. Explain what is meant by \'duration of short-term memory. \[1 mark\] 2\. Explain what is meant by \'coding\' in long-term memory. \[1 mark\] 3\. Outline the difference between the duration of short- term memory and the duration of long-term memory. \[4 marks\] 4\. Outline and evaluate research related to the features of short-term memory (coding, capacity and duration). \[16 marks\]