2 Example: A Card Trick. 4 Example: A Card Trick

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1 1 Sensory & Primary 2 Example: A Card Trick How much of what we perceive can we remember? Does your answer depend on anything? Delay? Amount of information? How long you get to study it? Select one of these six cards at random. Memorize it. Memorize it really well. Got it? How much of similar information you ve already seen? 3 Example: A Card Trick 4 Example: A Card Trick oops.. I lost one of the cards.. well, at least you can pick yours out of the remaining five... Is your card there?

2 5 Other Examples: Videos 6 Sensory & Primary Person change. Conversation. Door person change. Environment Sensory (iconic, echoic..) Attention Short Term (STM) Rehearsal Retrieval Long Term (LTM) This is the Modal model of memory (e.g., Atkinson & Shiffrin, Waugh & Norman) Attention = the gateway from sensory memory to STM. Rehearsal = maintaining information in STM. 7 Sensory & Primary : In the Brain 8 Iconic (Residual Activation in Vis. Cortex) Frontal planning control auditory episodes soma motor Temporal Parietal action language objects space vision Occipital What is span of sensory memory (e.g., how many beans can you perceive?) Jevons: throw beans out, glance at them, then report number. 3-4: 100% correct; 9 = 50% mark. Two kinds of memory, happens everywhere: Iconic/STM = Residual activation: lasts only as long as neurons fire.. (rehearsal keeps neurons firing) LTM = Synaptic changes: long-lasting encoding of memory (only strongly activated stuff is learned). Content of memory determined by where activations, synapses are. Residual activation lasts longer the higher in brain you go! 1920 s: Tachistoscope (T-scope): shutters tightly control time: 8.4 = 50% mark. Key problem: memory fades as subjects report items!

3 9 George Sperling to the Rescue: Partial Report Sensory Sperling s Experiments (pp ) Full report: Subjects report 33% of entire 12 item array: 4. Sensory information is briefly (< 1 sec) held in a Partial report: 3 out of 4 (75%) of cued line (3?). Sensory Register But itvision: could have Iconic been any line: must encode 3x3=9 items! Audition: Echoic Partial Report 10 Run Yourself.. Ready.. Short-Term (STM) Often Measured with Span Tests Normal capacity is about 7 +/- 2 Items Chunking Capacity can be improved by organizing information into groups. NFLCBSIRAMTV--> NFL CBS IRA MTV 11 Encode! A Q Recall bottom answer: 2Y6L T P W 1 2 Y 6 L

4 13 Iconic : Properties 14 Echoic (Auditory version of Iconic) Not an afterimage. Large capacity (esp. in the dark why?) Decays spontaneously (even while reporting): 500ms - 1s. 250msec of prior auditory information preserved (tones unaffected by masking after 250msec). But with language sounds, it is hard to draw line between pure auditory echo and higher-level linguistic representations. (Ignore convoluted discussion of suffix effect in book). Can be erased or masked Semantic vs. just visual content? graded mixture.. All these properties fall out of residual activation.. Except fact that it has no purpose: neurons need to fire long enough to activate higher-level representations! 15 Short-Term (Primary) 16 Capacity of STM Measured by digit span task. Environment Sensory (iconic, echoic..) Attention Short Term (STM) Rehearsal Retrieval Long Term (LTM) I will show you some digits, you encode them and then repeat them back. What is capacity of STM? How does occur? What is maintained?

5 17 Encode 18 Recall What were the digits? Answer: George Miller (1956; classic): capacity = 7 2 (Current magic number for non-verbal stimuli: 3 1) Second main point: it s 7 2 chunks! NFLCBSIRAMTV NFL CBS IRA MTV By developing very big chunks, Steve Faloon could encode nearly 100 digits! 19 The Brown-Peterson Task 20 Encode You will see three letters followed by a three digit number. Remember the three letters while counting backwards by threes from the three digit number.. QPZ 312

6 Percent Correct 21 Count! 22 Recall... And the three letter sequence was? QPZ Typical Brown Peterson Results Retention Interval (secs) decays over several seconds.. (much longer than iconic). Counting backwards interferes with the rehearsal process. 23 The Classic Dichotomy of Forgetting 24 Retro-Pro Examples Is just decay? What about interference? Of course, it s both. Also, two kinds of interference: Retroactive interference: present interferes with the past. Proactive interference: the past interferes with present. Retroactive: Interference 8am 9am 10am None Study French Sleep Take French Test Retroactive Study French Study Spanish Take French Test Proactive: Interference 8am 9am 10am None Sleep Study French Take French Test Proactive Study Spanish Study French Take French Test Retro/Pro describe the thing being interfered with.

7 25 Interference & Brown-Peterson Would you expect Retroactive interference in B-P? No, you don t need to recall the previous items! What about Proactive Interference (PI)? Yes! Trial % Correct In a follow-up study, Wickens (1972) used words as stimuli. For the first three trials, all words belonged to a single semantic category, fruits. On the fourth trial, the category shifted to meats, flowers, vegetables, or professions. A control group was given types of fruit on all four trials. The results of this follow-up experiment are given in Figure 4-5. First consider the condition in which fruits were given on all four trials. In this case, you can see that memory steadily declined over the four trials. Now consider the other conditions. The figure shows that in most cases, there was a release from proactive interference; that is, performance rebounded on Trial 4 when the material changed to a new category. Moreover, it appears that the magnitude of this rebound depended on how much the new material differed from the old material. When the new items were similar to fruits (e.g., vegetables) there was little or no release from proactive interference, but when the new items were very different from fruits (e.g., 26 Release from (Magnum) PI professions), the rebound was quite large. This demonstrates that the build-up and release of proactive interference applies to situations in which there is a change in the semantic category of items as well as to B-P with three words to remember. situations in which there is a shift in the type of item. First three trials are always fruits. Fourth trial was either fruits or.. Proportion Correct Professions Meats Flowers Vegetables Fruits Trial Figure 4-5. Proportion correct in free recall as a function of the number of trials (Wickens, 1972). For the first three trials, items consisted of types of fruit. Items given on the fourth trial were selected from the semantic category indicated above. CLASS RESULTS 27 Serial Position Curves: STM Decay Serial Position = position of item within overall list of items to be remembered: List: window, cat, frog, small, battery, drawing position 1 = window, 2 = cat, etc.. 28 Serial Position Curves: STM Decay Let s now examine whether a similar pattern of results is obtained for our experiment by looking at data from the Fall 1996 class. Keep in mind that our design is a bit different than that used by Wickens and colleagues. In our experiment, the first four trials consisted of items from one category, the next four trials consisted of items from a second category, and the last four trials consisted of items from a third category. Thus, there were three sets of four trials each. The data from these three sets were averaged together and then graphed in Figure 4-6, with the mean proportion correct plotted as a function of trials. To clarify, the value for Trial 1 represents the average of the first trial from each set, Trial 2 represents the average of the second trial from each set, and so on. By presenting the data in this fashion, we can directly compare the class results to those of Keppel and Underwood (1962). How do the results compare? Information in STM for last few items on list (recency). This disappears if S s have to count backwards after list..

8 29 Rehearsal Gets You Into LTM 30 Rehearsal Gets You Into LTM Environment Sensory (iconic, echoic..) Attention Short Term (STM) Rehearsal Retrieval Long Term (LTM) STM is the gateway to LTM: Rehearsal is the key. We ll talk a lot more about LTM later. Primacy effects: better memory for initial items. Due to extra chance to rehearse initial items. 31 STM Replaced by WM! 32 Evidence for the Phonological Loop Phonological Loop Central Executive Visuospatial Sketchpad Working model (Baddeley, 1986): Emphasizes use of memory for processing (not just storage). Two main modalities for storage: language, visuo-spatial. Executive is the biggest vacuum in cog. psych! Word span affected by number of syllables in words, reading rate! Phonological loop can replay & maintain 2sec of speech.

9 33 Working Working 34 Summary The most appealing aspect of WM theory is that we maintain information in an active state so we can work with it. STM = workspace of working memory theory. In the brain, WM depends critically on the frontal cortex we ll discuss this later when we talk about other frontal functions in higher-level cognition. Environment Sensory (iconic, echoic..) Attention Short Term (STM) Rehearsal Two kinds of memory, happens everywhere: Retrieval Long Term (LTM) Iconic/STM = Residual activation: lasts only as long as neurons fire.. (rehearsal keeps neurons firing) LTM = Synaptic changes: long-lasting encoding of memory (only strongly activated stuff is learned). Content of memory determined by where activations, synapses are. Residual activation lasts longer the higher in brain you go!