Psychology 439G/572B

1. Psychology 439G/572B Semantic Memory

2. What is Semantic Memory?

3. What is Semantic Memory? • General World Knowledge

4. What is Semantic Memory? • General World Knowledge • Facts

5. What is Semantic Memory? • General World Knowledge • Facts • Rules Thou Shalt Not Cheat

6. What is Semantic Memory? • General World Knowledge • Facts • Rules • Mathematics 2x2x2x2 = 16 Thou Shalt Not Cheat

7. What is Semantic Memory? • General World Knowledge • Facts • Rules • Mathematics • Categories 2x2x2x2 = 16 Thou Shalt Not Cheat

8. What is Semantic Memory? • General World Knowledge • Facts • Rules • Mathematics • Categories • Concepts 2x2x2x2 = 16 Thou Shalt Not Cheat

9. What is Semantic Memory? • General World Knowledge • Facts • Rules • Mathematics • Categories • Concepts • Language 2x2x2x2 = 16 Thou Shalt Not Cheat

10. What is Semantic Memory? • General World Knowledge • Facts • Rules • Mathematics • Categories • Concepts • Language • Meaning 2x2x2x2 = 16 Thou Shalt Not Cheat

11. This Class • No text; readings available from me • One paper, due at the end of classes • Research Paper (40%) • Literature Review on topic in semantic memory • Summarize current state of literature • 20-25 pages; follow APA guidelines • Undergraduates: at least 12 articles, 8 experimental, no more than 4 from class • Class Participation (40%) • First, you really, really have to show up • Second, you really, really have to participate in discussion of articles • Third, you have to present an article at least once in the term, and moderate the following discussion • Weekly Thought Paper (20%)

12. Weekly Thought Paper • Students will be required to write a weekly thought paper on the readings they were assigned for that week. • No more than 1-2 pages long • Should reflect if/how the various articles agreed or came into conflict, • Concerns the student had with methodology or interpretations in empirical articles, or • Other issues regarding the assigned articles that the student found interesting. • These will be collected at the end of class each week.

13. What We Will Be Studying… • The first week(s) should be review for some, new for others; A general summary of human cognition and especially the memory system • Methodologies of studying semantic memory • Models of Semantic Memory (including, why bother?) • Hierarchical Models, Feature List Models, Spreading Activation, Connectionist Models, High-dimensional Models • Perceptual Views of Semantic Memory • Effects of Age and Dementia on Semantic Memory • Categorization • Semantic Memory and the Brain

14. The Articles (for the undergraduates) • Since articles advance the science, they are the primary focus of the seminar • Some articles are review, more are empirical • It is important to understand both types of articles • Experimental papers • What is the theory or hypothesis being tested? What are the competitors? • Methods: How was the experiment done? What subjects, equipment, statistics were used? What are the IV and DV • Results: What happened? Was the theory supported? What would competing theories predict? • Conclusions: How do the results relate to the theory? Do you agree with this interpretation?

15. A Quick Intro (or Review) of Cognition • Cognition: The group of mental processes and systems used in learning, thinking, comprehending, remembering, planning, imagining, perceiving, attending, and communicating.

16. A Quick Intro (or Review) of Cognition • Cognition: The group of mental processes and systems used in learning, thinking, comprehending, remembering, planning, imagining, perceiving, attending, and communicating. • Or to be easier, cognition is thought • Memory: • The cognitive processes of acquiring, maintaining, and retrieving information for later use. • Storage “space” in which these processes take place

17. Memory • “Memory is the most important function of the brain; without it life would be a blank. Our knowledge is all based on memory. Every thought, every action, our very conception of personal identity, is based on memory…. Without memory, all experience would be useless” • Eldridge-Green, 1900, p. 1 • “Life is all memory except for the one present moment that goes by you so quick you hardly catch it going.” • Tennessee Williams • “Semantics. The curse of man.” • Maxwell, 1976

18. Methods of Studying Memory • Experimental cognitive psychology: • Reaction time experiments, priming, accuracy • Well controlled experiments • Indirect measures of internal processes • Modeling (Cognitive Science) • Computational models to understand memory and cognition • Semantic networks, connectionist networks • Simulations of human performance • Cognitive Neuropsychology • Brain damaged patients • Category specific deficits, dementia, aphasics, lesion data • Cannot provide adequate controls • Cognitive Neuroscience • Imaging technology: PET, fMRI, ERP, MEG • Either bad temporal or bad spatial resolution. Localization problematic

19. The Information Processing System Permanent memory Stimulus Sensory Store Short-term working memory Attention Response

20. Sensory Store • A very complete but brief (<1 second) representation of the stimulus • One for each sensory system; different lengths of time for each • Stimulus is encoded for further processing • Quickly decays; attention must be paid to stimulus or the information will not enter working memory • Because it decays so quickly, how can it’s capacity be measured (or properly reported by experimental subjects)?

21. Sperling (1960) • A clever experiment in which subjects are presented with an array of letters for 50 msec • If subjects are asked what they saw, they can only report about 4 letters However, in a second condition a tone is played after the array has been removed. Subjects are told that a low tone means report the bottom row, a middle tone means the middle row, and a high tone the high row. Subjects can remember 3 out of 4 letters. Since the tone is played after the array is no longer present, we can infer that people are actually recalling 9 out of 12 letters, and can only average 4 letters in the first condition because the memory decays before they can complete the report

22. The Information Processing System Permanent memory Stimulus Sensory Store Short-term working memory Attention Response

23. Working Memory • Also called Short-term memory • Both storage and processor; The more processing that needs to be done, the less storage is available • Quite limited capacity, compared to sensory store (very complete but brief) and permanent memory (limitless over a human lifespan) • The famous number: 7 ± 2 (Miller, 1956) • Once can hold 7 ± 2 items in working memory • However, this can be moderated, somewhat, be re-encoding the data. This process is sometimes called “chunking”

24. Working Memory Example • How many letters can you remember: A D F B I G U I B R B C I A B M W T V D C I B M Now, try again: A D F B I G U I B R B C I A B M W T V D C I B M • Re-encoding the letters into larger but more meaningful chunks allows you to remember more of the letters (Miller, 1956). This is why phone numbers, SIN numbers, etc. are separated into sections • 519-661-2111 • This process does require some mental effort (takes longer). It also requires the help of permanent memory.

25. Baddeley & Hitch (1974) • A more detailed version of working memory

26. The Information Processing System Permanent memory Stimulus Sensory Store Short-term working memory Attention Response

27. A Competing Theory of Memory • Craik and Lockheart proposed a “levels of processing” system. • Any perceived stimulus will receive processing • However, those that receive minimal attention are only processed in shallow memory • Those that receive more intentional processing are stored more deeply and more meaningfully in memory

28. Levels of Processing • Imagine a task in which pairs of words are presented queen broom In one condition of the experiment, subjects have to mentally count the number of vowels for both words 5 In another level, subjects have to mentally make a sentence out of the target words: The queen had never held a broom Then the subjects are presented with a recall task for the target words. Guess which group did better?

29. Permanent Memory • Also called Long-term memory. Informally, it’s what’s gotten past your attentional and working memory bottlenecks and actually been stored permanently in your brain. • “Divided” into Episodic Memory and Semantic Memory • Episodic memory, simply, is memory tied to specific events in your life • For instance, your 13th birthday • Your episodic memory and mine are quite different • Semantic Memory is all information not tied to a specific episode: language, world knowledge, concepts, etc. • Semantic memory can be inferenced: Does a tiger breathe? • Your semantic memory and mine are quite similar

30. Memory Example • Bird, cold, antarctic, feathers, beak, eggs, swims, aquatic, warm-blooded, can’t fly, eats fish, waddles, black and white, tuxedo

31. Related Issues for Memory • Automatic vs. Controlled Processing • Top-down (conscious) processing vs. bottom-up (data-driven) processing • Representation • Brain Function

32. Automatic vs. Controlled Processing • Automatic Processes • Performed without conscious awareness • Often unintentional (Stroop task) Green, Red • Generally performed in parallel • Consume few attentional resources • Controlled Processes • Require conscious control • Performed serially • Take longer to execute • fully controlled<-----------------------------> fullyautomatic (learning affects this) • 4 x 4. Now, 444 x 44

33. Top-Down vs. Bottom-Up Processing • Also called conscious process vs. data-driven processing • Examine the following pictures: Top-down processing relies on permanent memory to overcome problems with actually present stimuli Usually used automatically and without effort

34. Representation • How are things stored in memory? What form do these mental representations take? • External representations: words, pictures • Internal representations: Symbolic, distributed

35. Brain Function • How the brain functions is much more important to cognitive psychology now than 20 years ago • Neural networks use attributes of neuronal function to solve complex problems • Neuroimaging studies are exploding; these attempt to locate the neural substrate of cognitive tasks • Brain changes in older adults, demented adults, schizophrenia, etc. • Category specific deficits in lesioned patients and what this can tell us about semantic storage in the brain

36. The Spatial Metaphor for Memory • The concept of memory as a “space” in which things are “stored” is far older than the study of psychology • This space tends to be imagined in three dimensions • Things closer in this space tend to be related • This concept is even carried on in modern semantic models • Spreading activation models • High-dimensional models (but more than 3 dimensions) • This metaphor has gone hand in hand with the metaphor for memory that was dominant through the 70s and even 80s: the computer • None of these simple metaphors for memory is really flexible enough to account for all that memory can do, and do easily

37. The Information Processing System Permanent memory Stimulus Sensory Store Short-term working memory Attention Response

38. The Computer Metaphor Hard Disk Human Input Keyboard, Mouse, Disk CPU/Memory Input Monitor

39. Multiple Memory Stores • Increased sophistication over older, unitary stores • Most memory researchers still think in these terms, even when their own models are a good deal more complex • Multiple stores (sensory store, WM, etc) allow for a relatively easy explanation of why different memory tasks are performed with greater or lesser amounts of difficulty • For instance, why do you remember your 5th grade teacher but you can’t remember the phone number you just heard 5 minutes ago? • For the most part, these constructs have held up in the intervening 30 years, but each memory store has become considerably more complicated in theory • STM  Working Memory • LTM  Semantic vs. Episodic Memory; Semantic vs. Associative Memory; Implicit vs. Explicit Memory

40. Long Term Memory • How do we use long-term memory? • Recall: Yes, I remember my ex-girlfriend’s e-mail address • Recognition: Hey, isn’t that the prof who failed me? • Procedural: It’s like riding a bicycle… you never really forget • Musical: How did that song go again? • Linguistic: How can you finish the word: dip_ _ _ _ • It’s DIPLOMA. Get your mind out of the gutter! • Episodic: “So, that’s when the police showed up…” • Semantic: An ostrich is a bird. A whale is a mammal. • Explicit memory: Yes, the word AARDVARK was on the list • Implicit memory: How can I complete the word stem WH___ • Top-down processing: “I’m guessing they meant “Public Worship” • Note: there exists some overlap between some of these concepts, like explicit memory and recall/recognition

41. Recall vs. Recognition • These both involve conscious processes • Recognition: Have I seen something before? • Recall: What did I see? • Cued recall: OK, you saw some animals. What were they? • Free recall: Write down all the words you saw on the list • Recognition tends to be a lot better than recall. Up to 95% of a 1500-word word list can be identified as “previously seen”, i.e. recognized. • Why is recall more problematic than recognition? • Two-process model? • Recall: 1) search process, 2) recognition process • Recognition: 1) Recognition process • Accounts for frequency paradox: for recall, high frequency words are better, but for recognition, low frequency words are better. • Common words have more associative links; search is easier • Uncommon words have less baggage: old/new judgment is easier • But, what is recognition? Theory is vague.

42. More complex theories of recall/recognition • Multiple route approaches: There are 2 or more ways of encoding information in both recall and recognition • Recall (Jones, 1982) • Direct route: Cue allows direct access of TBR information • DOG  CAT • Indirect route: Cue allows recall via inference • LEASH  DOG  CAT • Recognition (Gardiner & Java, 1993) • Familiarity: (know response) “I know I’ve seen that guy before” • Contextual information (remember response) “Oh yeah, that’s the guy who ran into my car.” • Both familiarity and actual recall are part of recognition • These processes may be related to the distinction between semantic and episodic memory

43. Implicit and Explicit Memory • Explicit memory: These are the processes tapped by recall and recognition processes: conscious remembering • Implicit memory: When previously presented stimuli affect subsequent behavior, though they cannot consciously be recalled. • Example: • A list of words is presented; the subject studies the list • The subject is then given a word-stem completion task: • WH______ -- CH______ -- JU______ and told to complete the words with any valid English word, but not to use any words in the list previously studied • Results: subjects much more likely to complete the word stems with words in the lists, though A) they were told not to, and B) these completions are not the most frequent for those word stem (e.g. whale vs. whisper)

44. Implicit and Explicit Memory • This process is called “repetition priming” and is similar to the “semantic priming” we will learn much about. • An exposure to an instance “primes” that word for later use, though the word is below the conscious threshold • The distinction between implicit and explicit memory was first demonstrated in anterograde amnesiacs • As expected, the people with amnesia were very poor at conscious (explicit) retrieval attempts. • However, they demonstrated normal or near normal performance on implicit tasks (word-stem completion, anagram solution, degraded picture identification) • All a good deal of evidence that implicit memory is less affect by aging than explicit (though this is controversial) • These results all suggest a distinction between implicit and explicit memory processes.

45. Semantic vs. Episodic • Tulving (1972) proposed the distinction between semantic and episodic memory, though concepts of personal and impersonal knowledge had been around for decades. • Semantic memory: World knowledge, facts, language • Episodic memory: Memory tied to specific events • Now Tulving and collaborators (Wheeler, Stuss, and Tulving (1997) argue the essential feature of episodic memory is its autobiographical nature, rather than the type of material encoded or stored • Also, the creation of semantic memory necessarily requires episodes, so episodic memory is integral to semantic memory. • How does semantic memory affect episodic memory?

46. Autobiographical and Episodic Memory • Is there a distinction between the two? • Nelson, 1997, p. 357: “What I ate for lunch yesterday is today part of my episodic memory, but being unremarkable in any way it will not, I am sure, become part of my autobiographical memory – it has no significance to my life story” • There are often errors in autobiographical memories as in episodic memories. For instance, up to 40% cannot remember minor hospitalizations when asked about them only a year later. • Structures of Autobiographical memory: • Lifetime periods (school, work) • General events (holiday in Europe) • Event-specific : memories and images for a single event

47. Do we forget things from LTM? • Or are they just “retrieval failures?” Forgetting itself as a concept needs to be defined. • First theory: Decay • Memories actually fade over time, like an old B&W photo • Supported by behaviorist theory: memories are just like habits • However, not supported by cognitive theory (or experimental results). This theory would predict that older information is always remembered more poorly than newer information • Second Theory: Interference • Instead, some researchers argued that intervening information interfered between the encoding and retrieval processes

48. An example of an interference study: • Subjects learn a paired-word list: • List A tall-bone park-flea plan-leaf grew-cook nose-fight rabbit-few • They learn this list so that when any first word is presented, they can reply the second word • However, then they are asked to learn a new list: • List B tall-safe park-house plan-window grew-pencil nose-bench rabbit-card • When this is done, they are asked to use the List A pairs one more time. As you might guess, they cannot do it well.

49. But is this forgetting? • Let’s define forgetting as actual disappearance from memory. It’s gone, caput, finito. Does this actually happen? • Evidence suggests that LTM is actually permanent, except for: • Alzheimer's and other dementias • Brain injury • Instead, the current thought on LTM, now often called “Permanent Memory” (what a giveaway) suggests that retrieval failures are the reason we cannot instantly and perfectly recall information. • So, what are these “retrieval failures” and what causes them?

50. Retrieval failures • First, however: Did we really learn it? • “We must never underestimate one of the most obvious reasons for forgetting, namely, that the information was never stored in memory in the first place” (Loftus, 1980, p. 74) • Attention must be paid to a stimulus. The stimulus must be rehearsed in some manner. Both of these bottlenecks must be overcome in order for information to get into PM • OK, so we learned it. What are Retrieval Failures? • A RF familiar to you is the Tip-of-the-tongue (TOT) phenomenon. • You are in “TOT state” when you are unable to access information you know you have stored in PM • However, you usually have access to some information about the word, often phonological