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Chapter 5

Chapter 5.doc

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Department
Psychology
Course Code
PSYCH 2H03
Professor
Judith Shedden

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Chapter 5 THE ROUTE INTO MEMORY • Information processing: Complex mental events such as learning, remembering, or deciding actually involved a large number of discrete steps • Figure 5.1: Each enclosed shape represents a separate event or process, and the arrows represent the flow of information from one event to the next. The research goal was to make the charts more and more complete by analyzing each box into still smaller boxes, continuing until the entire process could be described in terms of elementary information-processing components. The Modal Model • Our information processing involves different kinds of memory (short-term and long-term memory) • Short-term memory holds on to information currently in use o Limited in how much it can hold but, most important, information in short-term memory is instantly and easily available to you • Long-term memory (LTM) contains all of the information you remember • At any point in time, much of the material in LTM lies dormant, neither influencing nor influenced by your current thoughts. Correspondingly, the process of retrieving information from LTM, and thus making the information available for use, often requires some hunting, and this can sometimes be effortful and slow. Working Memory and Long-Term Memory: One Memory or Two? • Free recall procedure: o Participants are read a series of words o Use lists of about 30 words o Immediately after the last word is read, participants are asked to repeat back as many words as they can • People usually remember 12 to 15 words in such a test o More likely to remember the first few words on the list (primary effect) o Likely to remember the last five or six words on the list (recency effect)  The U-shaped serial position curve shows the relation between position within the series and likelihood of recall (Figure 5.2) • As participants try to keep up with the list presentation, they will be placing the words just heard into working memory, and this will bump the previous words out of this memory. o As participants proceed through the list, their working memories will contain only the half dozen words that arrived most recently o Any words earlier than these will have been pushed out by later arrivals o The last few words stay in place (don’t get bumped out) • Materials in working memory are readily available – easily and quickly retrieved. When the time comes for recall, working memory’s contents are accurately and completely recalled. • According to the modal model, the transfer of material from working memory to LTM depends on processes that require time and attention. o When participants hear the first word, they repeat it over and over to themselves (memory rehearsal). o The first few items on the list are privileged  For a brief moment, “bicycle” was the only word participants had to worry about, and so it had 100% of their attention lavished on it o Words later in the list receive even less attention. o Words later in the list literally are rehearsed fewer times than words early in the list. • Early words have a greater chance of being transferred into LTM because they didn’t have to share attention with other words, and so more time and more rehearsal were devoted to these early words than to any others. o With a greater chance of being transferred into LTM, the list’s early words also have a greater chance of being recalled after a delay, and that’s what shows up in our data as the primacy effect. • A modification of the procedure: Immediately after hearing the list, participants count backward by threes, starting from 201. They do this for just 30 seconds, and then they try to recall the list. o The chore of counting backward will displace working memory’s current contents; that is, it will bump the last few list items out of working memory.  The simple chore of counting backward will eliminate the recency effect o The counting backward should have no impact on recall of the items earlier in the list: These items are being recalled from long-term memory, not working memory. LTM is not dependent on current activity. • Figure 5.3: With immediate recall, or if recall is delayed by 30 seconds with no activity during this delay, a strong recency effect is detected. In contrast, if participants spend 30 seconds on some other activity between hearing the list and the subsequent memory test, the recency effect is eliminated. This interpolated activity has no impact on the pre-recency portion of the curve. • Working memory is limited by its size, not by ease of entry or ease of access. o The slower list presentation should have no influence on working-memory performance. o Figure 5.4: Presenting the to-be-remembered materials at a slower rate improves pre-recency performance but has no effect on recency. • Using more familiar or more common words would be expected to ease entry into long-term memory and does improve pre-recency retention, but it has no effect on recency. • The recency and pre-recency portions of the curve are open to separate sets of influences and obey different principles. This strongly indicates that these portions of the curve are the products of different mechanisms, just as the modal model proposes. A CLOSER LOOK AT WORKING MEMORY The Function of Working Memory • When information is currently in use or likely to be needed soon, it is held in working memory. • Someone with a larger-capacity working memory is likely also to be a more efficient reader, confirming the role for working memory in reading. • Likewise, people with a larger capacity are better off in many types of reasoning skills, making it clear that working memory matters here, too. The Holding Capacity of Working Memory • For many years, working memory’s capacity was measured with a digit-span task. o People are read a series of digits and must immediately repeat them back. • “7 plus-or-minus 2” items  working memory’s capacity is around seven items or, more cautiously, at least five items and probably not more than nine items • George Miller proposed that working memory holds 7 plus-or-minus 2 chunks. The term “chunk” is a deliberately unscientific-sounding term; instead, he proposed, working memory holds 7 plus-or-minus 2 packages, and what those packages contain is largely up to the individual person. • The flexibility in how people “chunk” the input can easily be seen in the span test because performance in this task turns out to depend enormously on how the person thinks about or organizes the items. • This chunking process does have a cost attached. o In remembering the chunks, the person can sometimes lose track of what the original items actually were. o If a person memorizes the sequence “H,O,P,T…” by chunking it as “ho,pit,” and so on, this could easily produce a memory error: The person might remember “I” as the fourth letter in the sequence, when, in truth, this letter was inserted merely to make the second chunk pronounceable. • The chunking process takes some effort. o Attention is required to repackage the materials when assembling the letters into syllables, or the syllables into words. o The greater the amount of repackaging, the fewer the items that can be retained. • Example of a guy who is a fan of track events o When he hears numbers, he thinks of them as finishing times for races. o With strategies and with a considerable amount of practice, he has increased his apparent memory span from the “normal” 7 digits to 79 digits. o But what has changed through practice is merely this person’s chunking strategy, not the size of working memory itself. o When tested with sequences of letter, rather than numbers, his memory span was a six consonants. The Active Nature of Working Memory • Operation span: designed to measure the efficiency of working memory when it is “working” • After participants were asked to read a series of sentences, they were asked to recall the final words in the sentences. If the participant can do this successfully with two sentences, she is asked to do the same task with a group of three sentences, and then with four, and so on, until the limit on her performance is located. o This task involves storing some materials (the ending words) for later use in the recall test, while simultaneously working with other materials (the full sentences). o This juggling of processes is exactly what working memory must do in its function in day-to-day life. o Thus, performance in the operation-span test is likely to reflect the efficiency with which working memory will operate in more natural settings. • There are strong positive correlations between working-memory capacity (WMC) and many other measures: the verbal SAT, tests of reasoning, reading comprehension, and so on. o These correlations are all obtained when the more active measure of working memory – namely, operation span – is used. o These findings strengthen the overall claim that working memory is not a passive storage box but is instead a highly active information processor. The Working-Memory System • Working memory is a system built out of several components. o At the center of the system is the central executive, a multipurpose processor capable of running many different operations on many different types of material. o It is the central executive that does the real “work” in working memory, and so if one has to plan a response or make a decision, these steps require the executive. o Working memory often relies on low-level helpers, which serve as internal scratch pads, storing information you will need soon but don’t need right now.  Visuospatial buffer: used for storing visual materials  Rehearsal loop: used for storing verbal materials o Try reading the next few sentences while holding on to the list of numbers: “1, 4 ,6, 4, 9.”  The numbers were maintained by one of working memory’s helpers – namely, the rehearsal loop. While the helper provided this maintenance, the central executive was free to continue reading.  While mere storage handled by the helpers, the executive is available for other, more demanding tasks. The Rehearsal Loop • Storing numbers while reading o Working memory’s central executive must first identify the numbers, but then the executive needs to shuffle these numbers off to storage so that it’s not burdened with them.  That way, the executive will be free to work on other things.  To do this, the executive relies on the rehearsal loop. o Specifically, the executive uses the process of subvocalization (you silently say the numbers to yourself) to pronounce the numbers. o Once the executive has initiated the speech, and once the speaking is underway, the executive can turn to other matters. The burden of holding on to the numbers is now carried by the “inner voice,” not the executive. o Subvocalization produces a representation of these numbers in the phonological buffer.  An auditory image is created in the “inner ear.”  The executive “reads” the contents of the buffer; then the executive initiates the next pronunciation by the inner voice, to begin another cycle, and at that point it can go back to its other business. o In this way, the executive is needed only once per cycle: to read the contents of the buffer and launch the
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