chapter 4

1. Chapter 4 Short-Term or Working Memory

3. The Modal Model of Memory

4. Memory systems can be distingushed on the basis of : Structural characteristics. Immutable qualities of the physical system. Control processes. Cognitive operations performed on information in a store. Presumably, control processes are under the volitional control of the person.

5. Examples of Structural Characteristics Duration: How long information persists in the memory store (e.g., seconds, minutes, hours, days) Capacity: How much information can be stored in the memory store (e.g., small amount, large amount, unlimited amount) Coding format: The form in which information is stored (e.g., visual, acoustic, meaningful)

6. Examples of Control Processes Selective Attention: Focusing attention on some information to the exclusion of other. Rehearsal: The process of repeating information to one’s self. Visual Imagery: Converting information into mental images

7. Characteristics of Sensory Memory (Iconic Memory) Structural Characteristics: Brief duration (perhaps 1/2 second) Large capacity (more information is available than the person can report) Sensory coding (information in original or veridical form) Forgetting – rapid decay, erasure process Control Processes: Selective attention Pattern recognition

8. Characteristics of Short-Term Memory Structural Characteristics: Short duration (perhaps 20 or 30 seconds) Limited capacity (about 7 +/- items) Acoustic coding (?) Forgetting – decay, possibly interference Control Processes: Rehearsal Chunking

9. Characteristics of Long Term Memory Structural Characteristics: Long duration (some information is stored permanently) Large capacity (perhaps infinite) Semantic encoding (meaning is stored) Forgetting: interference, possibly decay Control processes Elaborative coding Retrieval

10. Memory systems also differ with regard to function Sensory memory: Hold information for identification. Short-term memory: Hold information for immediate use. Long-term memory: Hold information for later use.

12. Research with the Brown-Peterson Paradigm

13. Basic Paradigm On each trial, the participant is typically given three things to remember (three letters, three numbers, three words etc.) The retention interval varies between trials. Typical retention intervals vary from 0 sec (immediate recall) to 18 sec. The participant is required to engage in a rehearsal prevention task during the retention interval

14. Demonstration

19. Results from Peterson and Peterson (1959)

20. Conclusions There is a system that stores information for no longer than 20 to 30 seconds if the information is not rehearsed. This contrasts with long-term memory where information can be held indefinitely without rehearsal.

21. Forgetting in STM

22. Forgetting in STM

23. Interference theory

24. Two sources of interference Retroactive interference: When “new” learning interferes with “old”. Proactive interference: When “old” learning interferes with “new”.

25. Retroactive interference in STM

26. Proactive Interference

28. Release from proactive interference

32. The magical number 7 (+/- 2)George Miller (1957)

33. The memory span task Present short string of items to participant. Test memory for string immediately. Gradually increase length of string until participant makes an error. Longest string the participant can recall without error represents memory span.

34. Demonstration

35. X B J

39. L T Z D B

43. M G C V K R P

47. H W R Q B F L D X

51. N C G S Z T J V M P Y

56. Chunking

57. Chunking

58. Chunking

59. Chunking

60. SWA EPT CTA HTE RHE

62. SWA EPT CTA HTE RHE

64. PET THE WAS CAT HER

69. THE CAT WAS HER PET

70. Acoustic coding in short-term memory (Conrad, 1964)

71. Basic experiment A string of letters is presented visually to the participant Memory is tested immediately Conrad looked at the pattern of confusion errors

72. Confusion Errors Confusion errors occur when the participant recalls one letter instead of another, i.e., the participant confuses the two letters. Conrad was interested if confusion errors were the result of visual similarity or acoustic similarity

73. Example

74. What Conrad found Acoustic confusion errors were more likely than visual confusion errors (even though the presentation of the letter strings was visual). The pattern of acoustic confusion errors mirrored those that occur on an acoustic letter recognition task.

75. Conclusion

76. Additional evidence supporting the notion of short-term memory The serial position curve Anterograde amnesia

77. The Serial Position Curve

78. A possible explanation

79. A Test:

81. What would happen if . . .

83. What would happen if . . .

85. Conclusion

86. Anterograde Amnesia

87. Characteristics of Anterograde Amnesia Patients display “normal” memory for events that occurred prior to the brain damage. Patients appear to have “normal” short term memory abilities. Difficulty is that patients don’t appear to be able to form new long-term memories.

89. Implication of Anterograde Amnesia

90. Doubts about Short-Term Memory

91. Doubts based on Logical arguments Data

92. Logical Arguments against Short-Term Memory It is more parsimonious to have one system where representations vary in strength than two systems which store information for varying abounts of time There is no clear means for measuring the capacity of short term memory. Therefore, it is not possible to distinguish between short and long-term memory on the basis of capacity

93. Findings which do not support the notion of short term memory Visual coding in short term memory Long term recency effects Implicit memory in amnesic patients

94. Visual Coding in Short Term Memory (Posner, 1969)

95. The Experiment Participant is presented a pair of letters Participant responds as quickly as possible if the two letters are the same (“yes”) or not (“no”). The time taken to respond (reaction time) is recorded.

98. Modification of original experiment Present letters successively with a visual mask following the first letter Vary the time interval between the letters

99. Predictions What should we predict if all information is coded acoustically in short-term memory? What should we predict if visual information can be maintained in short-term memory?

101. Conclusion

102. Long-term recency effects Recency effects are not necessarily related to short-term memory This is certainly true of long-term recency effects Long-term recency effects occur when the last portion of a sequence is well remembered, but the time intervals are so long that it is not apparent how short-term memory could be involved.

103. Example of long-term recency effects Write down all of the Presidents of the US that you can remember. How many of the first 5 did you recall? (Washington, J. Adams, Jefferson, Madison, Monroe) How many of the middle 5 did you recall? (Hayes, Garfield, Arthur, Cleveland, Harrison) How many of the last 5 did you recall? (Carter, Reagan, G. Bush, Clinton, G. W. Bush)

106. Other explanations of the serial position curve Distinctiveness: Beginnings and endings are distinctive and consequently are well remembered Interference: memory for the early items is interfered with by later items memory for later items are interfered with by early items memory for middle items are interfered with by both early and late items

107. Implicit memory in amnesic patients

108. Implicit Memory

109. Examples of Implicit Memory Driving on the right side of the road without consciously recalling having learned to do so. Avoiding a particular food without consciously recalling the fact that you got sick when you ate it last. Disliking someone without consciously recalling the horrible things they have done to you.

110. A Laboratory Paradigm Present learning material under some other pretext (i.e., so that the participant doesn’t know that his or her memory for the material will be tested. Test memory with something that doesn’t appear to be an explicit or obvious test of memory.

111. Example Have participants rate words with regard to their pleasantness food psychology alcohol Have participants solve the following word anagram problems yopolgyshc mpentterda

113. Critical Finding

114. Implication

115. Conclusions about Short-Term Memory Short-term memory is a popular concept that helps us to understand a great deal of research Psychologists can and have raised questions about its veracity There maybe alternative frameworks for thinking about memory

116. Working Memory: Another Name for Short-Term Memory or Something New?

118. The Workbench Analogy Like a workbench, working memory provides work space storage space Like a workbench, the more space taken up by storage, the less space is available for work

119. Working Memory and Intelligence

120. An Illustration

121. An Illustration

122. A Test of the Working Memory Hypothesis (Baddeley, 1986) Participants asked to engage in a grammatical reasoning task (True or false? “B is not preceded by A” -- AB) At the same time they are also asked to remember a short string of digits which are presented just before the reasoning task The length of the string (memory load) is varied

123. Results:

124. Conclusions As predicted by the working memory hypothesis, reasoning ability decreased with increasing memory load. Maximizing memory load, however, did not produce a catastrophic failure of working memory This suggested to Baddeley that working memory was more complex

125. Baddeley’s Notion of Working Memory

126. A Test of his Model

127. The Experiment The participant is given two tasks The first task involves keeping a mental count of the number of times a figure shows up on a computer screen The second task involves either: saying “the” as rapidly as one can tapping a finger on the table as rapidly as one can

128. Prediction

129. Results

130. A revision to Baddeley’s model of working memroy