Lecturer: Dr. Benjamin Amponsah, Dept. of Psychology, UG, Legon Contact Information: bamponsah@ug.edu.gh College of Education School of Continuing and Distance Education 2014/2015 – 2016/2017
Session Overview • We turn our attention to how we access or retrieve information stored in short-term/working memory. Think about the equivalent question of how we retrieve information from long-term memory which is more meaningful to us. Such a question is particularly interesting when retrieval, whether short- or long-term memory, is extremely rapid and out of conscious awareness. So the question is how does the rapid process of retrieval happen in the STM/Working memory? Slide 2
Session Objectives At the end of the session, the student will be able to • Conceptualize short-term memory and its brief trace life • Discuss serial versus parallel search in the short-term memory • Explain the concepts self-terminating search and exhaustive search in the short-term memory • Appreciate pronunciation time as important in retrieving information from short-term memory • Affirm that without rehearsal the active information stays maximally for approximately 30 seconds Slide 3
Session Outline The key topics to be covered in the session are as follows: • Topic One: Retrieval from STM/Working Memory • Topic Two: Self-terminating or exhaustive Search • Topic Three: Word-length effect on retrieval Slide 4
Topic One RETRIEVAL FROM STM/WORKING MEMORY Slide 5
Reading List • Ashcraft, M. H. (2006). Cognition (4 th edn.), London: Pearson Education Int. • Galotti, K. M. (2004). Cognitive Psychology: In and out of the laboratory (3 rd Edn.). Belmont, CA: Wadsworth. • Hunt, R. R. & Ellis, H. C. (1999). Fundamentals of Cognitive Psychology (6 th edn.), New York: McGraw-Hill. • Willingham, D, B. (2001). Cognition: The thinking animal . NJ: Prentice-Hall. Slide 6
Retrieval from STM/Working Memory • Evidence converge on the fact that many cognitive psychologists are reluctant to endorse the concept of short- term memory that is structurally different from long-term memory. • For that reason, we will combine the two as we discuss retrieval from the short-term/working memory. Sternberg’ s Ideas on the Search Process • Saul Sternberg (1969) in several experiments found some surprising things about how we retrieve information from short-term memory. Slide 7
The Search Process • Before considering his experiments, let us look at the search process in the STM. • Sternbergs foremost question was whether we search for information held in STM in a parallel or in a serial manner. • Parallel search involves a search for information in which several stores or slots of information are simultaneously examined to match the target. Slide 8
The Search Process • Serial search on the other hand involves a search for information in which several stores or slots of information are sequentially examined to match the target. • In serial search, the longer the list is, the longer it should take to decide if there is a match. • We can also determine whether the search is: self-terminating or exhaustive . Slide 9
Topic Two SELF-TERMINATING OR EXHAUSTIVE SEARCH Slide 10
Self-terminating/Exhaustive Search • Self-terminating search stops when a match is found. If you engage in a self-terminating search, you will stop when you find a match. On the average, successful search takes less time because you do not continue searching after you have found the match. • Exhaustive Search on the other hand means that even after a match is found, you continue looking through every other item in the set. This means that even after you have found the target, you check the remaining lot until you have finished. With this kind of search, it takes just as long for successful as for unsuccessful searches . Slide 11
Stenberg’s Experiment Stenberg’s Experiments on Memory (STM). • Participants were first presented with a set of seven or fewer letters . These were to be encoded and held in STM and may be called “memory set”. • After, a single letter, called a probe , was presented, the participant’s task was to decide, as quickly as possible, whether the probe was in the memory set . Slide 12
Stenberg’s Experiment • Next, a single letter, called a probe , was presented, the participant’s task was to decide, as quickly as possible, whether the probe was in the memory set . • For example, the memory set might be B K F Q P M and probes might be K (Yes, in the memory set) and D (No, not in the memory set). • Stenberg’s results argue for serial, exhaustive search as the way we retrieve information from STM. Slide 13
Stenberg’s Experiment • His explanation is that: a) the search process itself may be so rapid and have such momentum that makes it hard to stop when it starts. b) From a processing point of view, it may be more efficient just to let the search process finish and then make one decision at the end, instead of making several decisions, one after each item in the memory set. Slide 14
Further Evidence of Search • Hunt (1978) findings showed that people of all sorts including college students, senior citizens, people with exceptionally good memories, retarded people etc., showed results consistent with the idea that retrieval from STM uses serial, exhaustive search ( and not parallel self- terminating search) , although search rate changes with the group, being faster for people with exceptional memories and slower for aged. Slide 15
Further Evidence of Search • Later work by other investigators shows an important twist. • For example, DeRosa and Tkacz (1976) suggests that STM handles ordered, organized material differently from unorganized material . • Their study makes an important point. Memory processes apparently work differently as a function of the material (stimuli) to be remembered. Slide 16
Topic Three WORD-LENGTH EFFECT ON RETRIEVAL Slide 17
Other Factors • Beyond the search process we can also look at what happens to the information to be retrieved. • Note that as items in short-term/working memory decay in level of activation the speed of our access to them slows. Slide 18
Other Factors • A fact of short-term memory is that without rehearsal information decays rapidly (about 30 sec). • Another compelling evidence on retrieval from the short- term/working memory concerns word length effect on retrieval (Baddeley, 1975). • For example, how long it takes to pronounce Burma on one hand, and Czechoslovakia has effects on the memory span and the ability to retrieve. Slide 19
Summary • Summary (about retrieval of information from STM/working memory) • The crucial factor in recall from the short- term/working memory seems to be the word length or how long it takes to pronounce a word . • the ability to r ehearse has also been critical and it has been demonstrated through the prevention of Rehearsal Prevention Task that without rehearsal information simply decays in the STM • To keep and extend the trace life of the information we need to constantly refresh the information. Slide 20
Summary • Finally, the nature of information , whether it’s organized or unorganized will affect recall of information from STM. • Search is based on serial and exhaustive protocols. Slide 21
Sample Questions • Describe what you understand by exhaustive search. • What is the distinction between serial and parallel search? • Describe factors that determine retrieval from short- term/working memory . Slide 22
References • Baddeley, A. D. (1976). The Psychology of memory . New York: Basic Books. • DeRosa, D. V., & Tkacz, D. (1976). Memory scanning of organized visual material. Journal of Experimental Psychology: Human learning and Memory, 2, 688-694. • Hunt, E.B. (1978). Mechanics of verbal ability. Psychological Review , 85, 109-130. Slide 23
References • Stenberg, S. (1966). High-speed scanning in human memory. Science, 153, 652-654. • Sternberg, S. (1969). Memory scanning: Mental processes revealed by reaction time experiments. American Scientist , 57, 421-457. Slide 24
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