Memory
Information-Processing Model of Memory
* Sensory memory: it’s purpose is to hold an internal copy of physical information just long enough for the system to select something in particular to attend to; that information then gets transferred to  . . .
* STM: our conscious workspace
* Processes that control the flow and makeup of information have their locus in STM (e.g., coding, rehearsal, retrieval strategies…)
Sensory memory
* Representational format: Modality-specific
* Iconic memory: visual sensory memory
* Echoic memory: auditory sensory memory
* Haptic memory: touch sensory memory
* Duration
* Iconic memory: 250 ms
* Echoic memory: 2-3 seconds
* Capacity: Modality-dependent
* Forgetting: Information decays if not further processed
Testing the duration and capacity of iconic memory
* A letter array is displayed for 50 ms
* In the whole report condition, subjects try to report all the letters
* In the partial report condition, subjects report only a single row of letters
Duration and capacity of iconic memory
Short-term memory
* Duration: 20 sec when you are distracted and can’t rehearse
* Unlimited when maintaining information through repetition that you want to remember, like a phone number; termed “maintenance rehearsal”
* Format: Visual verbal stimuli are stored in STM in an acoustic format 
* Sound-alike errors: when they can’t remember, people might say V instead of E, but not F instead of E.
* Capacity: The magical number 7+2
* Chunking (1 4 9 2 1 7 7 6 1 9 4 5)
* Expertise
* Retrieval: We retrieve information from STM by using a serial exhaustive search, rather than a serial self-terminating search
Forgetting from Short-term memory
* Decay theory of forgetting
* Memory traces dissipate as time passes and those memories are not used (see sensory memory)
* Interference theory of forgetting
* Memories are lost when they are bumped out or replaced by the formation of new memories
* Experiment (for the result, see the next slide)
* Some subjects sees 12 items, at a rate of 1 item per second. Total time: 12 seconds
* Other subjects also see 12 items, but at a rate of 4 items per second. Total time: 3 seconds.
* Decay theory predicts more forgetting in the first condition because more time has gone by.
* Interference theory predicts equal forgetting in both conditions because the same number of new memories are being formed. 
Support for the interference theory of forgetting in STM
Working Memory
* STM was described as a single system responsible for information flow and control
* However, STM is also used for comprehension of language, problem solving, and visual imagery (e.g., mental rotation task)
* Baddeley revamped the idea of STM and renamed it  “working memory”
* Working memory is a set of independent subsystems that share attentional resources
Some working memory findings
* Memory span task: listen to simple elements and immediately report in the order of their presentation
* K.F.: memory span is impaired, but IQ is spared
* Dual task methodology: have subjects do two tasks concurrently, each of which taxes the interdependent systems (e.g., the auditory working memory slave system and the central executive)
* Findings
* (1) As auditory working memory load increases from saying “the the the …” (concurrent articulation task), to saying “1 2 3 4”, to holding six random digits in memory, reasoning task performance decreases 
* (2) If subjects do a memory span task and a concurrent articulation task, for which auditory working memory is responsible, memory span performance decreases
* (3) Concurrent articulation eliminates sound-alike errors for visually presented materials because the scratch-pad is used instead
* (4) Concurrent articulation does NOT affect memory span for visual objects that cannot be named because storage of the visual objects does not require auditory working memory
* (5) Word-length effect: Memory span is shorter for longer words because longer words more quickly consume the limited resources of auditory working memory
Mental rotation in visuo-spatial working memory
Serial position effect
* Since we cannot directly observe them, how do we know these two mental structures -- called STM and LTM -- actually exist?
* Experiment
* All subjects are presented 15 words, one at a time, for 2 seconds each.
* Some subjects are asked, immediately after the words have been presented, to recall as many words as they can, in any order.
* Serial position effect
* Memory performance is better for the first few words (the “primacy effect”) and the last few words (the “recency effect”) that have been presented.
* For other subjects, there is a delay of 30 seconds after the list has been presented.
* During this delay, the subject may, for example, be asked to count backwards by 4’s from 569. 
* See next slide for result
Short-term vs. long term memory
* The 30 s delay eliminated the recency effect, but did not impair the primacy effect.
* This indicated that the recency effect must be due to STM, while the primacy effect must be due to LTM.
Long-term memory (LTM)
* Memory for information that is no longer being rehearsed. 
* If a person is distracted for a couple minutes from rehearsing a new phone number, yet remembers the number, then it must have been stored in LTM. 
* Capacity: infinite
* Duration: permanent
* Forgetting: retrieval failure 
* Memories are available, but not necessarily accessible
* Format: meaning and visual
Long-term memory
Three key phases of the LTM process
* Encoding
* The mental processes we use to process information determine the strength and longevity of memory for that information.
* Storage
* There are many different types of long-term memory.
* Retrieval
* The circumstances under which one tries to retrieve memories, such as the nature of the memory test, influence the success of that retrieval.
Encoding into (explicit) LTM
* Four factors affecting the strength of (explicit) LTM
* Elaborative rehearsal (processing information for meaning) promotes better LTM for facts than rote rehearsal (repetition)
* Regardless of how you rehearse, spaced rehearsal is better than massed rehearsal 
* It’s better to study 1 hour of information for an hour at 3 different times than for 3 hours all at one time
* Dividing attention during encoding impairs LTM
* Use of imagery to code information in a visual format also promotes better LTM
* Picture superiority effect: pictures are remembered better than words
LTM Systems
Declarative (Explicit) Long-Term Memory
* Conscious retrieval and declaration of past events and known facts
* We often retrieve information from LTM into STM and then consciously respond in a particular manner
* Two forms of declarative memory
* Episodic memory and semantic memory
* Episodic memory
* Includes where, when, and to whom something happened 
* Reexperiencing, often in visual terms, of a past event
Semantic memory I
* Semantic memories are knowledge representations that are built through integrating similar experiences across time
* Each time you are told that the sun rises in the east leaves an episodic memory of that event
* But once you have many episodic memories of being told that fact, then you forget the episodes in which you learned that fact and you just remember the fact itself
* This process is sometimes termed “abstraction” and the memory left is sometimes described as an “abstract” form of memory
* Many different types of semantic memory
* Words and their meanings 
* Facts: “George Washington’s face is on a $1 bill.”
* Categories: “A canary is a type of bird.” 
* Schemas (see slide 27 for definition)
Semantic Memory II: Semantic Networks
* Our semantic memory is organized by meaning, like a thesaurus
* In contrast, a dictionary is organized alphabetically
* Each concept is represented as a node
* When the word “red” is presented, the node for red becomes activated and, if that activation is sufficient, you 
* Become conscious of that word
* Become conscious of the meaning of that word
* Are able to say that word or respond to that word
Semantic Memory III
* Spreading activation
* When red becomes activated, the activation spreads from red to other concepts that are connected to red
* Three examples of spreading activation at work
* Free association
* If you’re asked to say the first word that comes to mind when you’re presented the word red, you’ll say blood or roses or fire engine or apple or . . .; but you won’t say words that are unrelated to red
* Automatic activation of task relevant knowledge
* When someone says to you, “Please set the table for dinner.”, there are many things left unsaid, such as what to set on the table, in what arrangement to set those things, how many places to set, etc. Your semantic memory fills in that missing information when activation spreads from table and dinner to related concepts.
* Semantic priming (see next slide)
Semantic Memory IV: Semantic Priming
* Semantic priming 
* Imagine a task where you are presented two words in succession and your task is to say just the second word; the experimenter is going to measure how long it takes you to say the second word
* If a word unrelated to red, like the word box, is presented before   the word red, you will be relatively slow to say the word red (it will take you about ½ sec) 
* However, if  a word related to red, like the word apple, is presented before the word red, you will be relatively fast to say the word red (it will take you about 1/3 sec)
* The difference in speed is called a semantic priming effect
* The reason you’re faster to say red after apple than after box is because the activation of apple spread to red and, as a result, red already had a head start when the word red was actually presented.
Nondeclarative (implicit) memory
* Unconscious (automatic) retrieval of information that influences behavior; responses are, in some respects, not mediated by STM
* Skills and habits: reading, typing, bike riding, tying shoes, brushing teeth, washing dishes 
* Priming: any influence of a single past episode on current behavior that occurs without a person’s intentional retrieval or awareness 
* Simple conditioning: cat and can opener
* Nonassociative learning: Habituation and sensitization
Brain and Memory
* The limbic system is critical for memory formation and recall
* Hippocampus: Critical for forming new explicit (conscious) memories
* Amygdala: Important role in emotional memories
* H.M.’s hippocampus was removed and he suffered from anterograde amnesia
Explicit vs. Implicit memory
* Amnesic patients and normal controls tested for memory of words learned previously
* Amnesics performed poorly on explicit memory tasks
* Performance on implicit memory tasks was like control subjects
Encoding-Retrieval Similarity
* Enhancing the similarity between conditions at study and test can improve LTM. 
*  The physical environment 
*  Emotional state (mood)
*  Physiological state (drugs)
*  Psychological state (depression) 
*  Cognitive processes that are involved in processing information
Ebbinghaus’s Forgetting Curve
* Over the first three days, the rate of forgetting is very high
* % correct drops from 57% to 25%
* Over the next 27 days, the rate of forgetting is very low
* % correct drops from 25% to 21%
* In summary, the rate of forgetting is initially very high, but becomes very low
Interference and Forgetting
Schemas: Benefits and Costs
* Schema: Knowledge representations, built through integrating similar experiences across time, which allow us to predict the nature of repeated activities (e.g., birthday parties) and environments (e.g., offices)
* Schemas are used to construct long-term memories of the stimulus at encoding and to reconstruct long-term memories at retrieval 
* Sometimes this can be helpful, as in the following passage from Bransford & Johnson (1972)
* Sometimes this can be harmful, as in the following Brewer & Treyens (1981) picture of the office
Read this passage before going to the next slide 
* The procedure is actually quite simple. First you arrange items into different groups. Of course one pile may be sufficient depending on how much there is to do. If you have to go somewhere else due to lack of facilities that is the next step; otherwise, you are pretty well set. It is important not to overdo things. That is, it is better to do too few things at once than too many.  In the short run this may not seem important but complications can easily arise. A mistake can be expensive as well. At first, the whole procedure will seem complicated. Soon, however, it will become just another facet of life. It is difficult to foresee any end to the necessity for this task in the immediate future, but then, one never can tell. After the procedure is completed  one arranges the materials into different groups again. Then they can be put into their appropriate places. Eventually they will be used once more and the whole cycle will then have to be repeated. However, that is part of life. 
Schema benefits
* When subjects read the preceding passage without a title or when subjects were given a title to the passage after they had read it, comprehension scores and recall scores were low. 
* However, subjects given the title “Washing Clothes” before reading the passage scored twice as well in both comprehension and recall tests. 
Study this picture for 30 s before going to the next slide

Schema Costs
* Many subjects recall seeing books in the picture of the office, when there are no books in the picture.
* Another example
* Roediger & McDermott (1995) 
* Present subjects with lists of words (e.g., bed, rest, awake, tired, dream, wake, night, blanket, doze, slumber, snore, pillow, peace, yawn, and drowsy)
* Many subjects recall having heard the word “sleep” in the list, even though it was not presented
Other memory missteps
* The misinformation effect (Loftus)
* Subjects are shown a slide show in which a Datsun runs a stop sign and hits a pedestrian.
* Later they are asked “Did another car pass the Datsun as it reached the yield sign?”
* Later, 30% more of these subjects incorrectly said that they had been shown a slide with a yield sign than if they had not been asked the “leading question”, many with a high degree of confidence.
* In one study of 28 convicted felons that were proved innocent by DNA tests, all had been convicted on the basis of eyewitness testimony.
More memory missteps
* Recovered memories or false memories?
* According to Freud, repressed memories are memories of (typically) traumatic events that people have forced from their conscious memory into their unconscious
* People sometimes claim to recall traumatic events (such as childhood sex abuse) after having forgotten these events for many years
* If these events really occurred, were forgotten, and were later remembered, then these are called recovered memories.
* If the memories of these events were really the product of suggestions made by an unwitting therapist to the patient, then these are called false memories. 
More memory missteps
* Illusory memories
* Students (N = 24) were presented a booklet in which there were four stories of childhood events. 
* Three of these stories were true.
*  The three true stories had been gathered by previously contacting the family of the student. 
* One of the stories, about being lost in a mall, was false. 
* Subjects were asked to try to remember these events and to describe what they remembered in detail. 
* If they didn’t remember, they were told to say so.
* After first reading the booklet, 7 of 24 subjects “remembered” being lost in the mall.
* In follow-up interviews, 6 of 24 subjects continued to remember being lost in in the mall. 
Other important memory concepts
* Autobiographical memory
* Reminiscence peak of adolescence and early adulthood
* Transitional firsts, such as 1st and 4th years of college
* Flashbulb memories are very clear, visual, detailed memories of a new, important, emotional event.
* Childhood amnesia
* The past is distorted in a way that inflates our own self-importance and enhances our own self-image
* Hindsight bias is the after-the-fact feeling that some event was very predictable even though it wasn’t predicted beforehand.
Other important memory concepts, cont.
* Prospective memory
* Memory for things that need to be done in the future
* Remembering to do some thing at a particular time and remembering what to do at that time
* Keeping the script for the to-be-done activity in an activated state helps prospective memory
* Metamemory
* People’s knowledge of their own memory skills and abilities
* The accuracy with which people guess about how likely they are to be able to remember something or how effective some memory strategy or learning strategy may be for them