1. PSYCHOLOGY: Themes and Variations Weiten and McCann
Chapter 7 :
Human Memory
Copyright © 2007 by Nelson, a division of Thomson Canada Limited

2. Human Memory: Basic Questions
How does information get into memory?
How is information maintained in memory?
How is information pulled back out of memory?
Memory is much more than taking in information and putting it in some mental compartment…we have to get it back out, too. Many psychologists study factors that help or hinder memory storage and retrieval…thus attempting to answer 3 basic questions…
How does information get into memory?
How is information maintained in memory?
How is information pulled back out of memory?

3. Fig 7. 1 – Three key processes in memory
Fig 7.1 – Three key processes in memory. Memory depends encoding, storage, and retrieval. Some theorists have drawn an analogy between these 3 processes and elements of information processing by computers; however, the storage analogy is somewhat misleading. Stored on a hard drive, information remains unchanged indefinitely and you can retrieve an exact copy. Memory storage is a much more dynamic process. Our memories change over time and are rough reconstructions rather than exact copies of past events.

4. Encoding: Getting Information Into Memory
The role of attention
Focusing awareness
Selective attention = selection of input
Filtering: early or late?
The first step in getting information into memory is to pay attention to it.
Attention involves focusing awareness on a narrowed range of stimuli or events.
Selective attention is a term used by many psychologists to describe this paying-attention-to-something process; however, the word selective is really redundant…attention IS selection of input.
Usually, attention is likened to a filter in an information-processing model of memory…the filter screens out most stimuli, while allowing a select few to get by.
Much research has been done to determine whether this filtering process occurs early in the information processing sequence or later.
It appears that both may be at play…sometimes you are paying attention to someone talking with you at a party, and you suddenly hear your name from across the room.

5. Fig 7. 2 – Models of selective attention
Fig 7.2 – Models of selective attention. Early-selection models propose that input is filtered before meaning is processed. Late-selection models hold that filtering occurs after the processing of meaning. There is evidence to support early, late, and intermediate selection, suggesting that the location of the attentional filter may not be fixed.

6. Levels of Processing: Craik and Lockhart (1972)
Incoming information processed at different levels:
Deeper processing = longer lasting memory codes
Encoding levels:
Structural = shallow
Phonemic = intermediate
Semantic = deep
According to Craik and Lockhart, whether or not we will be able to remember something depends on how deeply we processed the information. Figure 7.4 illustrates different levels of processing.

7. Fig 7. 3 – Levels-of-processing theory
Fig 7.3 – Levels-of-processing theory. According to Craik and Lockhart (1972), structural, phonemic, and semantic encoding—which can be elicited by questions such as those shown on the right— involve progressively deeper levels of processing, which should result in more durable memories.

8. Fig 7. 4 – Retention at three levels of processing
Fig 7.4 – Retention at three levels of processing. In accordance with levels-of-processing theory, Craik and Tulving (1975) found that structural, phonemic, and semantic encoding led to progressively better retention.

9. Enriching Encoding: Improving Memory
Elaboration: linking a stimulus to other information at the time of encoding
Thinking of examples
Visual Imagery: creation of visual images to represent words to be remembered
Easier for concrete objects: Dual-coding theory
Self-Referent Encoding: Making information personally meaningful
Elaboration is a process by which a stimulus is linked to other information at the time of encoding…for example, you are studying phobias for your psychology test, and you apply this information to your own fear of spiders.
Elaboration often consists of thinking of examples…self-generated examples seem to work best.
Visual imagery involves the creation of visual images to represent the words to be remembered…concrete words are much easier to create images of (example, juggler vs. truth).
Dual-coding theory holds that memory is enhanced by forming semantic or visual codes, since either can lead to recall.
Self-referent encoding involves deciding how or whether information is personally relevant, that is, information that is personally meaningful is more memorable.

10. Storage: Maintaining Information in Memory
Analogy: information storage in computers ~ information storage in human memory
Information-processing theories
Subdivide memory into 3 different stores
Sensory, Short-term, Long-term
Plato and Aristotle compared memory to a block of wax that differed in size and hardness for various individuals…remembering was like stamping an impression into the wax…
Today, with technological advances, the analogies have become much more sophisticated...
Atkinson and Shiffrin, 1968, proposed an analogy between information storage by computers and information storage in human memory – the information processing approach.
Basically, this approach divides memory into 3 different stores: sensory, short-term memory, and long-term memory.
This is depicted in the following figures.

11. Fig 7. 7 – The Atkinson and Shiffrin model of memory storage
Fig 7.7 – The Atkinson and Shiffrin model of memory storage. Atkinson and Shiffrin (1971) proposed that memory is made up of three information stores. Sensory memory can hold information just long enough (a fraction of a second) for a small portion of it to be selected for longer storage. Short-term memory has a limited capacity, and unless aided by rehearsal, its storage duration is brief. Long-term memory can store an apparently unlimited amount of information for indeterminate periods.

12. Sensory Memory
Brief preservation of information in original sensory form
Auditory/Visual – approximately ¼ second
George Sperling (1960)
Classic experiment on visual sensory store
Sensory Memory is basically information preserved in its original sensory form for a brief time. This type of memory allows the sensation to linger briefly after the sensory stimulation is over…in the visual system, an afterimage.
The visual and auditory sensory stores appear to decay after about ¼ second
George Sperling (1960) performed a classic experiment on the visual sensory store, illustrating how brief the sensory store actually is…his experiment is depicted in the following figure.

13. Fig 7. 8 – Sperling’s (1960) study of sensory memory
Fig 7.8 – Sperling’s (1960) study of sensory memory. After the subjects had fixated on the cross, the letters were flashed on the screen just long enough to create a visual afterimage. High, medium, and low tones signaled which row of letters to report. Because subjects had to rely on the afterimage to report the letters, Sperling was able to measure how
rapidly the afterimage disappeared by varying the delay between the display
and the signal to report.

14. Short Term Memory (STM)
Limited capacity – magical number 7 plus or minus 2
Chunking – grouping familiar stimuli for storage as a single unit
Limited duration – about 20 seconds without rehearsal
Rehearsal – the process of repetitively verbalizing or thinking about the information
Short-term memory is defined as a limited-capacity store that can maintain unrehearsed information for up to about 20 seconds.
George Miller (1956) wrote a famous paper called “The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information," where he illustrated that the average person can hold between 5 and 9 chunks of information in STM.
A chunk of information is a group of familiar stimuli stored as a single unit…for example, the following numbers can be thought of as 7 individual numbers or they can be chunked together in groups of 2, 3, etc.
STM also has a limited duration…in other words, information can only be kept there for a brief time before it is lost, unless rehearsal occurs.
Rehearsal is the process of repetitively verbalizing or thinking about the information…keeping it in use.
Peterson and Peterson (1959) conducted a study illustrating how quickly information is lost from STM…this study is illustrated on the next slide.

15. Fig 7. 9 – Peterson and Peterson’s (1959) study of short-term memory
Fig 7.9 – Peterson and Peterson’s (1959) study of short-term memory. After a warning light was flashed, subjects were given 3 consonants to remember. Researchers prevented rehearsal by giving the subjects a 3-digit number at the same time and telling them to count backward by 3 from that number until given the signal to recall the letters. By varying the amount of time between stimulus presentation and recall, researchers were able to measure how quickly information is lost from short-term memory.

16. Short-Term Memory as “Working Memory”
STM not limited to phonemic encoding
Loss of information not due only to decay
Baddeley (1986) – 3 components of working memory
Phonological rehearsal loop
Visuospatial sketchpad
Executive control system
30 years of research eventually uncovered a number of problems with the original model of STM…STM is not limited to phonemic encoding, as originally thought, and decay is not the only process responsible for loss of information.
These and other findings indicated that STM might be a much more complicated aspect of memory.
Alan Baddeley ( ) proposed a more complex model of STM that characterizes it as “working memory," with 4 components.
The phonological rehearsal loop represented ALL of STM in the original model. This component is active when one uses recitation to temporarily hold on to information.
The visuospatial sketchpad allows temporary holding and manipulation of visual images (mentally rearrange the furniture in your bedroom).
The executive control system handles the limited amount of information juggled at one time as people engage in reasoning and decision making…at work when you weigh pros and cons of something.
The episodic buffer is a temporary, limited capacity store that allows the various components of working memory to integrate information, and that serves as an interface between working and LTM.

17. Fig 7. 11 – Short-term memory as working memory
Fig 7.11 – Short-term memory as working memory. This diagram depicts the revised model of the short-term store proposed by Alan Baddeley (1986), who views STM as a mental scratchpad or temporary workspace. According to Baddeley, working memory includes three components: a phonological rehearsal loop, a visuospatial sketchpad, and an executive control system.

18. Long-Term Memory: Unlimited Capacity
Permanent storage?
Flashbulb memories
Recall through hypnosis
Debate: are STM and LTM really different?
Phonemic vs. Semantic encoding
Decay vs. Interference based forgetting
While most researchers agree that LTM has an unlimited capacity; that is, our memory store never gets FULL, much debate remains over whether storage is permanent.
Flashbulb memory and hypnosis based memory suggest that LTM is indeed permanent, that the only reason we forget is that we aren’t able to access information that is still in LTM (interference theory). Research shows, however, that flashbulb and hypnosis based memories are not always accurate. Is the information still there, or does it decay over time, and we make up for this by building up decayed memories so that they make sense?
And are STM and LTM really different stores? We used to think that phonemic encoding occurred in STM and semantic (or meaning based) encoding in LTM. Now we know that both occur for both. We also used to think that decay occurred in STM and interference in LTM, with regard to forgetting. Now, it is unclear what exactly occurs in LTM, it may be both.
Some researchers argue that STM and LTM are the same thing, that STM is just a little part of LTM that is in a state of heightened activation, although the multiple stores view is still dominant.

19. How is Knowledge Represented and Organized in Memory?
Clustering and Conceptual Hierarchies
Schemas and Scripts
Semantic Networks
Connectionist Networks and PDP Models
Clustering is the tendency to remember similar or related items in groups.
Conceptual hierarchies are multilevel classification systems based on common properties among items.
Schemas are organized clusters of knowledge about a particular object or event abstracted from previous experience.
A script is a particular type of schema, organizing what a person knows about common activities…for example going to a restaurant. Research shows that people are more likely to remember things that are consistent with their schemas than things that are not…the reverse is also true – people sometimes exhibit better recall if information really clashes with a schema.
Semantic networks consist of nodes representing concepts, joined together by pathways that link related concepts….explains why thinking of butter makes bread easier to remember…depicted on following slide.
Connectionist, or parallel distributed processing models, assume that cognitive processes depend on patterns of activation in highly interconnected computational networks that resemble neural networks….that is, this model of memory uses as inspiration the way neurons appear to handle information through connections…according to this model, specific memories correspond to specific patterns of activation in these networks.

20. Retrieval: Getting Information Out of Memory
The tip-of-the-tongue phenomenon
A failure in retrieval
Retrieval cues
Recalling an event
Context cues
Reconstructing memories
Misinformation effect
Source monitoring, reality monitoring
The tip-of-the-tongue phenomenon shows that recall is often guided by partial information about a word….retrieval cues.
Memories can also be reinstated by context cues…easier to recall long-forgotten events if you return after a number of years to a place where you used to live.
Memories are reconstructions of the past, which may not be entirely accurate. Research shows that reconstructions can be influenced by new information…the misinformation effect. Elizabeth Loftus has shown that eyewitness testimony can be influenced by information presented to witnesses. Example…showed a video of two cars in an accident…asked some people how fast the cars were going when they HIT each other, asked others how fast the cars were going when the SMASHED INTO each other…a week later asked whether there was any broken glass in the video…the “smashed into” group said yes, the “hit” group said no.
The misinformation effect is explained in part by the unreliability of source monitoring…the process of making attributions about the origins of memories…people make decisions at the time of retrieval about where their memory is coming from (did I read that somewhere or think of it on my own?…cryptomnesia is inadvertent plagiarism that occurs when you think you came up with it but were really exposed to it earlier).
Reality monitoring is a type of source monitoring involving determining whether memories are based in actual events (external sources) or your imagination (internal sources)…kidnapped by aliens? Possible error in reality monitoring.

21. Forgetting: When Memory Lapses
Retention: the proportion of material retained
Recall
Recognition
Relearning
Ebbinghaus’s Forgetting Curve
To study forgetting empirically, psychologists must measure it precisely. To measure forgetting, we must measure memory.
Retention refers to the proportion of material remembered or retained. Three types of tasks are used to measure retention…recall, which involves requiring subjects to reproduce information on their own without any cues…recognition, which involves requiring subjects to select previously learned material from an array of options…and relearning, which involves requiring subjects to relearn previously learned information to see how much LESS time or effort it takes them.
Hermann Ebbinghaus studied forgetting using retention in the late 1800s, by using himself as a subject. He found that retention and forgetting occur over time and plotted his data…the famous forgetting curve depicted on the next slide. Current research suggests that this curve is unusually steep, probably due to the fact that Ebbinghaus was using nonsense syllables that are difficult to encode semantically.

22. Fig 7. 17 – Ebbinghaus’s forgetting curve for nonsense syllables
Fig 7.17 – Ebbinghaus’s forgetting curve for nonsense syllables. From his experiments on himself, Ebbinghaus concluded that forgetting is extremely rapid immediately after the original learning and then levels off. However, subsequent research has suggested that this forgetting curve is unusually steep. (Data from Ebbinghaus, 1885)

23. Fig 7. 18 – Recognition vs. recall in the measurement of retention
Fig 7.18 – Recognition vs. recall in the measurement of retention. Luh (1922) had subjects memorize lists of nonsense syllables and then measured their retention with either a recognition test or a recall test at various intervals up to two days. As you can see, the forgetting curve for the recall test was quite steep, whereas the recognition test yielded much higher estimates of subjects’ retention.

24. Why Do We Forget? Ineffective Encoding Decay theory
Interference theory
Proactive
Retroactive
Research indicates that forgetting may be related to encoding, storage, or retrieval processes.
Much forgetting may only look like forgetting…it may have never been inserted into memory in the first place…pseudoforgetting…usually due to lack of attention so that encoding does not occur. Ineffective encoding occurs when you encode on a more superficial level than you need to…for example, you are distracted when studying and encode what you are reading on a phonemic rather than a semantic level.
Decay theory proposes that forgetting occurs because memory traces fade with time.
The negative impact of competing information on retention is called interference. Interference theory holds that people forget information because of competition from other material.
Proactive interference occurs when previously learned information interferes with the retention of new information, while retroactive interference occurs when new information impairs the retention for previously learned information.
Figure 7.20, presented on the next slide, illustrates the two types of interference.

25. Fig 7. 20 – Retroactive and proactive interference
Fig 7.20 – Retroactive and proactive interference. Retroactive interference occurs when learning produces a “backward” effect, reducing recall of previously learned material. Proactive interference occurs when learning produces a “forward” effect, reducing recall of subsequently learned material. For example, if you were to prepare for an economics test and then study psychology, the interference from the psychology study would be retroactive interference. However, if you studied psychology first and then economics, the interference from the psychology study would be proactive interference

26. Fig 7.21 – Estimates of the prevalence of childhood physical and sexual abuse. In one of the better efforts to estimate the prevalence of child abuse, MacMillan and her colleagues (1997) questioned a random sample of almost 10,000 adults living in the province of Ontario about whether they had been abused during childhood. As you can see, males were more likely to have experienced physical abuse and females were more likely to have suffered sexual abuse. Moreover, the data support the assertion that millions of people have been victimized by childhood sexual abuse, which is far from rare. (Based on
data from MacMillan et al., 1997)

27. Retrieval Failure Encoding Specificity Transfer-Appropriate Processing
Repression
Authenticity of repressed memories?
Memory illusions
Controversy
The encoding specificity principle holds that the effectiveness of a retrieval cue depends on how well it corresponds to the memory code that represents the stored item…the closer a retrieval cue is to the way we encode the info, the better we are able to remember.
The transfer-appropriate processing theory holds that when the initial processing of information is similar to the type of processing required by the subsequent measure of retention, retrieval is easier.
Repression involves the motivated forgetting of painful or unpleasant memories. Recent years have seen a surge of reports of repressed memories of child sexual abuse. The authenticity of these repressed memories is challenged by empirical studies that show that it is not at all hard to create false memories and that many recovered memories are actually the product of suggestion.
Roediger and McDermott (2000) have shown that when participants are asked to learn a list of words, and another target word that is not on the list but is strongly associated with the learned words is presented, the subjects remember the non-presented target word over 50% of the time…on a recognition test, they remember it about 80% of the time…a memory illusion.
While research clearly shows that memories can be created by suggestion, in cases of child sexual abuse memories, for example, this issue becomes quite emotionally charged. Some cases of recovered memories are authentic, and we don’t yet have adequate data to estimate what proportion of recovered memories of abuse are authentic and what proportion are not. Still, this controversy has helped inspire a great deal of research that has increased our understanding of the fallibility and malleability of human memory.

28. Fig 7.23 – The prevalence of false memories observed by Roediger and McDermott (1995). The graph shown here summarizes the recognition test results in Study 1 conducted by Roediger and McDermott (1995). Participants correctly identified words that had been on the lists that they had studied 86% of the time and only misidentified unrelated words that had not been on the lists 2% of the time, indicating that they were paying careful attention to the task. Nonetheless, they mistakenly reported that they “remembered” related target words that were not on the lists 84% of the time—a remarkably high prevalence of false memories. (Data from Roediger & McDermott, 1995)

29. The Physiology of Memory
Biochemistry
Alteration in synaptic transmission
Hormones modulating neurotransmitter systems
Protein synthesis
Neural circuitry
Localized neural circuits
Reusable pathways in the brain
Long-term potentiation
Anatomy
Anterograde and Retrograde Amnesia
Cerebral cortex, Prefrontal Cortex, Hippocampus,
Dentate gyrus, Amygdala, Cerebellum
From a biochemical perspective, memory appears to be related to alterations in synaptic transmission at specific sites. Durable changes in synaptic transmission may be the building blocks of memories. Other research shows that learning causes hormonal changes which may modulate activity in a variety of neurotransmitter systems. Protein synthesis has also been shown to be necessary for memory formation…if you give drugs that interfere with protein synthesis, memory is impaired (at least in chicks and rats).
From a neural perspective, memories appear to depend on localized neural circuits in the brain. These are reusable pathways in the brain that may be specific for specific memories. Research indicates that long-term potentiation occurs with learning. Long-term potentiation is a long-lasting increase in neural excitability at synapses along a specific neural pathway. This supports the idea that memory traces consist of specific neural circuits.
The anatomy of memory is complex, and many brain structures have been shown to be important in memory. Figure 7.24, on the next slide, illustrates the brain structures involved in memory, while the following slide, Figure 7.25, illustrates the two types of amnesia, retrograde (for prior events) and anterograde (for subsequent events).

30. Fig 7. 24 – The anatomy of memory
Fig 7.24 – The anatomy of memory. All the brain structures identified here have been implicated in efforts to discover the anatomical structures involved in memory. Although its exact contribution to memory remains the subject of considerable debate,
the hippocampus is thought to play an especially central role in memory.

31. Fig 7. 25 – Retrograde versus anterograde amnesia
Fig 7.25 – Retrograde versus anterograde amnesia. In retrograde amnesia, memory for events that occurred prior to the onset of amnesia is lost. In anterograde amnesia, memory for events that occur subsequent to the onset of amnesia suffers.

32. Are There Multiple Memory Systems?
Implicit vs. Explicit
Declarative vs. Procedural
Semantic vs. Episodic
Prospective vs. Retrospective
Implicit memory involves incidental, unintentional remembering, whereas explicit memory involves intentional recall. Many theorists argue that implicit and explicit memory rely on different encoding and retrieval processes, while others argue that they are each handled by independent memory systems (procedural – which is memory for actions, skills, operations and conditioned responses, and declarative – which is memory for factual information).
It is suspected that the declarative memory system handles explicit memory and procedural implicit memory.
Declarative memory can be subdivided into memory for personal facts (episodic) and memory for general facts (semantic).
Retrospective memory is memory for past events, whereas prospective memory is remembering to do things in the future.

33. Fig 7. 26 – Theories of independent memory systems
Fig 7.26 – Theories of independent memory systems. There is some evidence that different types of information are stored in separate memory systems, which may have distinct physiological bases. The diagram shown here, which blends the ideas of several theorists, is an adaptation of Larry Squire’s (1987) scheme. Note that implicit and explicit memory are not memory systems. They are observed behavioural phenomena that appear to be handled by different hypothetical memory systems (the procedural and declarative
memory systems), which cannot be observed directly.

34. Improving Everyday Memory
Engage in adequate rehearsal
Distribute practice and minimize interference
Emphasize deep processing and transfer-appropriate processing
Organize information
Use verbal mnemonics
Use visual mnemonics