Introduction to Long-Term Memory

Transcription

1 Introduction to Long-Term Memory Psychology 355: Cognitive Psychology Instructor: John Miyamoto 04/26/2018: Lecture 05-4 Note: This Powerpoint presentation may contain macros that I wrote to help me create the slides. The macros aren t needed to view the slides. You can disable or delete the macros without any change to the presentation.

2 Outline Finish discussion of the central executive (part of working memory) Introduction to long-term memory HM - a patient with a famous memory impairment What were his memory problems? Why did he display a specific pattern of memory abilities and disabilities? Multi-component model of long-term memory How do we know that short-term memory and long-term memory are based on different memory systems? Episodic memory versus semantic memory: How are they different? Implicit memory - how does it different from explicit (a.k.a. declarative) memory? Lecture probably ends here Summary: Frontal Lobe Damage & Functions of the Central Executive Psych 355, Miyamoto, Spr '18 2

3 Frontal Lobe Damage & Impaired Functioning of the Central Executive Central executive controls attention to relevant information and responses. Inhibits irrelevant information and responses. Frontal lobe damage leads to difficulty inhibiting irrelevant information and responses. Stroop task, Wisconsin card sort task, face recognition with irrelevant scenes: To respond correctly, you need to inhibit a response. People with frontal lobe damage have difficulty inhibiting tempting but mistaken responses. People differ in how effective they are at inhibiting irrelevant information. People who are better at inhibiting irrelevant information are better at performing cognitive tasks that require focusing on relevant stimuli. Return to Baddeley s List of Central Executive Functions Psych 355, Miyamoto, Spr '18 3

4 Baddeley s List of Functions of the Central Executive Only partially understood. Very active area of current research. Alan Baddeley chief developer of working memory theory (Baddeley calls the theory of the central executive a "ragbag") Controlling and allocating attention. Coordinating current activity of working memory with goals. Task switching. Multi-tasking. Selection and launching of responses. Inhibiting associated but inappropriate responses. Controlling the interface between STM and LTM, especially LTM search & retrieval. Chunking Introduction to Long-Term Memory Psych 355, Miyamoto, Spr '18 4

5 Psych 355, Miyamoto, Spr '18 5 Picture Showing the STM/LTM Distinction Outline - Introduction to Long-Term Memory Reminder: Distinction between STM / WM and LTM Different types of long-term memory Explicit versus implicit memory (declarative vs non-declarative memory) Episodic versus semantic memory Procedural memory Associative memory HM a famous clinical case What was HM's main memory problem? Evidence for distinction between STM & LTM Evidence for distinction between episodic and semantic memory Evidence for distinction between explicit memory and implicit memory.

6 Figure 6.1: Example of the STM/LTM Distinction LTM STM Diagram of Modal Memory Model Encoding, Retrieval & Consolidation Psych 355, Miyamoto, Spr '18 6

7 Control Processes Retrieval External World Sensory Store Short-Term Store Encoding Long-Term Store Encoding, Retrieval & Consolidation Encoding creating an LTM out of currently processed information. Retrieval bringing information that is stored in LTM back to STM Consolidation - creating a strong LTM by repeatedly retrieving and manipulating an LTM; and by associating it with other memories. List of Functions That Are Included in LTM Psych 355, Miyamoto, Spr '18 7

8 LTM Includes... Important information about the self and events in the world, but also,... Trivial information about what has happened in the recent past, Semantic knowledge, e.g., what is an apple, a pencil; which is bigger, a mouse or a moose; etc. How to do things: Tie your shoes, drive a car, dial a phone number, cook a meal,... Learned associations that are not explicit, e.g., the atmosphere of a dentist s office makes you feel apprehensive. Diagram Showing the Major Components of the LTM System Psych 355, Miyamoto, Spr '18 8

9 Different Types of Long-Term Memory Figure Different Types of Long-Term Memory Declarative memory (explicit memory) facts, knowledge, images Non-declarative memory (implicit memory) non-conscious memory that is expressed through change in behavior; it doesn t necessarily include conscious recollection. Intro to HM Psych 355, Miyamoto, Spr '18 9

10 HM A Famous Clinical Case HM initials of a man See links to his biography on the Psych 355 website. Intractable epilepsy. August 25, 1953: Medial temporal lobes (left and right) were surgically resectioned to treat his epilepsy. Removal of the hippocampus. Following surgery, HM had much milder symptoms of epilepsy, but he was found to have severe problems with memory.. Where is the Hippocampus? Psych 355, Miyamoto, Spr '18 10

11 This slide is based on instructional material that was downloaded from the Pearson Publishers website ( for Smith & Kosslyn (2006; ISBN ). Where is the Hippocampus? HM underwent bilateral removal of much of the hippocampus, amygdala and surrounding medial temporal cortices. Amygdala Hippocampus Schematic head facing up. Hippocampi are in red. HM s Memory Problem Psych 355, Miyamoto, Spr '18 11

12 HM s Memory Post-Surgery HM could carry on a conversation, understand current situations. Severely impaired memory for any events occurring after brain injury. (Severe anterograde amnesia) Some impaired memory for events occurring before injury. (Some retrograde amnesia) Could learn new skills like sewing. Could learn some new semantic information, e.g., his brain surgery was in 1953, but he learned that there was a president named Kennedy who was assassinated. Diagram Showing Multiple Memory Systems Psych 355, Miyamoto, Spr '18 12

13 Episodic & Semantic Memory HUMAN MEMORY SHORT-TERM MEMORY Memory Terminology Including Types of Amnesia Psych 355, Miyamoto, Spr '18 13

14 Discussed on Earlier Slide More Memory Terminology Explicit memory (declarative memory) Episodic memory - memory for personal experiences Semantic memory - memory for facts Implicit memory (non-declarative memory) Priming exposure to one stimulus can affect ability to perform a cognitive task. Procedural memory - memory for how to do things, e.g., how to type at a computer. Associative and non-associative learning Amnesia Anterograde amnesia for events occurring after brain injury. Retrograde - amnesia for events occurring before brain injury. Psych 355, Miyamoto, Spr '18 Back to HM s Memory Problems 14

15 HM's Memory Problems Anterograde amnesia very severe; he could not form new permanent episodic memories. Retrograde amnesia very severe for preceding 4 days; some impairment up to 11 year preceding. Retrograde amnesia was temporally graded, i.e., less amnesia for events that were farther in the past Declarative memory severely impaired Episodic memory very severe Semantic memory severe but he could still learn some new general facts. Procedural memory relatively intact HM learned to sew. HM learned to draw mirror images. Diagram Showing that HM s Memory Problem Pertains to Encoding Psych 355, Miyamoto, Spr '18 15

16 HM's Explicit Memory Problem Control Processes Retrieval External World Sensory Store Short-Term Store Encoding Long-Term Store (Remember that this diagram is an over-simplification) HM's worst problem was encoding from STM (WM) to LTM. Impaired transfer from STM to LTM. STM (WM) was still functioning because he could understand the current situation. Note: This diagram omits the role of the hippocampus in consolidation (probably HM had difficulty with consolidation as well as encoding). Diagram Showing Multiple Memory Systems Psych 355, Miyamoto, Spr '18 16

17 Episodic & Semantic Memory HUMAN MEMORY Next: How do we know that STM & LTM involve different brain mechanisms? SHORT-TERM MEMORY Serial Position Curve Provides Evidence for STM / LTM Distinction Psych 355, Miyamoto, Spr '18 17

18 How Do We Know that STM and LTM Involve Different Brain Mechanisms? % Recalled Evidence from the Serial Position Curve: Figure 6.3 Serial Position Curve Subject views list of 20 words, one word at a time. Each word is presented for 2 seconds. After viewing the list, subject attempts to recall as many words as possible. "Serial position" refers to the position of a word in the list, i.e., 1 st, 2 nd, 3 rd,..., 19 th, 20 th. Serial Position Curve shows the percentage of times a word in each position was recalled correctly. Interpretation of Standard Result for Serial Position Curve Psych 355, Miyamoto, Spr '18 18

19 % Recalled Interpretation of Standard Result for Serial Position Curve Claims (to be substantiated in subsequent slides) Figure 6.3 Serial Position Curve Primacy effect is due to transfer to LTM. Recency effect due to words retained in STM. Standard result for serial position curve is evidence for STM/LTM distinction. Primacy Effect Serial Position Recency Effect Psych 355, Miyamoto, Spr '18 How to Prove that Primacy is Due to Transfer to LTM? 19

20 How to Prove Primacy Effect Is Due to Transfer to LTM? Rundus (1971) presented words at the rate of 1 word per 5 seconds. 20 words in the list. Subjects were instructed to rehearse words aloud. What Subject Sees What Subject Says car car, car, car,... stone car, stone, car, stone, car,... top car, stone, top, car, stone, top, This study has 2 dependent variables: Frequency of recall for words in each position Number of rehearsals for words in each position Results for Rundus Experiment Psych 355, Miyamoto, Spr '18 20

21 % Recalled Number of Rehearsals Results for Rundus (1971) Study Figure 6.4 to the right: Red solid line: Serial position curve (standard result) Blue dotted line: Number of times a word in each position was rehearsed. Figure 6.4 Effect of Overt Rehearsal Serial Position Blue dotted line correlates perfectly with the serial position curve (red dotted line) except for the recency effect. This supports claim that primacy effect is due to transfer to LTM. How to Prove that Recency Effect Due to Retention in STM? Psych 355, Miyamoto, Spr '18 21

22 % Recalled How to Prove Recency Effect Is Due to Retention in STM? Dashed line shows effect of counting backwards by 3 s for 30 seconds after presentation of list. Glanzer, M., & Cunitz, A. R. (1966). Two storage mechanisms in free recall. Journal of Verbal Learning and Verbal Behavior, 5, Figure 6.5 Effect of Counting Backwards Counting backwards prevents retention of words in STM, so recency effect disappears. This result supports the hypothesis that the recency effect is due to retention of recent words in STM. Serial Position No recency effect Psych 355, Miyamoto, Spr '18 How We Know that STM & LTM Are Different Mechanisms - Summary 22

23 How Do We Know that STM and LTM Involve Different Brain Mechanisms? (Conclusion) Assumption of separate STM & LTM explains facts about the serial position curve. Neuropsych evidence of double dissociation between STM & LTM. o o HM & Clive Wearing had normal memory span, e.g., 5-8 digits KF had reduced memory span, e.g., about 2 digits. LTM was ok. STM LTM HM, Clive Wearing OK Impaired K. F. Impaired OK Psych 355, Miyamoto, Spr '18 Surprise Memory Test Items 23