Chapter 6: Memory
Define and give examples of anterograde and retrograde amnesia.
Anterograde Amnesia - A loss of memory for events that occur after a brain injury. Ex. When H.M. was 27 years old, part of his hippocampus was removed in order to stop his severe epileptic seizures. After the operation, his LTM and STM appeared normal, but something was wrong. Two years later, he still believed that he was 27. The surgery had destroyed the mechanism that transfers information from STM to LTM. He was unable to recall events and facts he had experienced since he was 27. Retrograde Amnesia - A loss of memory for events that occured prior to a brain injury. Ex. In 1994, head injuries from a car crash led 36 year old Perlene GRiffith-Barwell with retrograde amnesia so severe that she forgot virtually everything she and learned about everything and everyone she had known over the previous 20 years. She thought she was still 16 and did recognize her husband, or her four children. Her memories never fully returned. Unlike, Perlene, most victims of retrograde amnesia gradually recover their memories.
Discuss the research examining constructing memories.
By constructing our own versions of what we have seen and heard, we may remember an event differently from the way it actually happened. These errors, called false memories, can occur in relation to anything from the objects present in a room to the identity of an armed robber. On each of sixteen trials, college students heard a different list of words. Each list to a particular theme. The students falsely, but confidently, recognized the theme words from twelve of the sixteen lists. The chance of accurately recognizing the listed words was greater when the students had been allowed to recall them shortly after hearing them. The results suggest that the participants could not always distinguish words they had heard from those they had not heard. The never-presented theme words "belonged" with the lists of presented words and apparently were "remembered" because they fit logically into the gaps in the students' memories. The students' knowledge of words that should have been included on the lists created a "memory" that they were presented. Studies such as this one make it clear that memory is constructive and that memory distortion and inaccuracy are commonplace.
Discuss the controversy surrounding repressed memories.
Cases in the 1990s have resulted in imprisonment as adult children claimed to have recovered childhood memories of physical or sexual abuse at the hands of their parents. The juries in these trials accepted the assertion that all memory of shocking events can be repressed, or pushed into an inaccessible corner of the mind where subconscious processes keep it out of awareness for decades yet potentially subject to accurate recall. A lot of mental activity occurs outside of awareness. Research on implicit memory shows that our behavior can be influenced by information of which we are not aware. Research on motivated forgetting suggests that people may sometimes be able to suppress information willfully, so that it is no longer accessible on a later memory test. Skeptical psychologists realize that subconscious memory and retrieval processes exist and that child abuse and other traumas are all too common. But to these psychologists, the available evidence is not strong enough to support the conclusion that traumatic memories can be repressed and then accurately recalled. Any given "recovered" memory, they say, may actually be a distorted or constructed memory. The recovery of traumatic memories is at least possible but that the implantation of false memories is also possible and has been demonstrated repeatedly in controlled experiments. It is not easy to decide whether any particular case is an instance of recovered memory or false memory, especially when there is no objective corroborating evidence to guide the decision. Repressed Memory: A painful memory that is said to be kept out of consciousness by psychological processes.
Describe and explain the brain structures and regions that are the bases for memory.
Communication among brain cells takes place at the synapses between axons and dendrites using chemicals called neurotransmitters that are released at the synapses. The formation and storage of new memories are associated with at least two kinds of changes in synapses. Repeatedly sending signals across a particular synapse increases the number of special little branches, called spines, that appear on the receiving cell's dendrites. When two neurons fire at the same time and together stimulate a third neuron, the other neuron will later be more responsive than before to stimulation by either neuron alone. This process of "sensitizing" synapses is called long-term potentiation. Other patterns of electrical stimulation can weaken synaptic connections, a process called long-term depression. Changes in the sensitivity of synapses could account for the development of conditional responses and other types of learning and for the operation of working memory. In the hippocampus, these changes appear to occur at synapses that use the neurotransmitter glutamate. Other neurotransmitters, such as acetylcholine, also play important roles in memory formation. Combined neural activity in many parts of the brain allow use to encode, store, and retrieve memories. The complexity of the biological bases of these processes is underscored by research showing that different aspects of a memory--such as the sights and sounds of some event--are stored in different parts of the cerebral cortex. The hippocampus and thalamus send nerve impulses to the cerebral cortex, and it is in and around the cortex that long-term semantic and episodic memories are probably store--but not just in one place. Specific aspects of an experience are stored in or near different regions of the cortex. A memory, however, involves more than one sensory system. So memories are both localized and distributed. Certain brain areas store specific aspects of each remembered event, but many brain systems are involved in experiencing a whole event. The cerebellum is involved in the storage of procedural knowledge, such as dance steps and other movements. The hippocampus and various regions of the cerebral cortex are active during memory retrieval. Retrieving memories of certain experiences, such as a conservation or a tennis game, reactivates the sensory and motor regions of the brain that had been involved during the event itself.
Define context-dependent and state-dependent memories and give examples of each. Explain the mood congruency effect.
Context-Dependent Memory - Memories that are helped or hindered by similarities or differences between the contexts which they are learned and recalled. Ex. Some students find it helpful to study for a test in the classroom where the test will be given. State-Dependent Memory - Memory that is helped or hindered by similarities or differences in a person's internal state during learning versus recall. Ex. If people learn new material while under the influence of marijuana, they tend to recall it better if they are tested on the material while under the influence of marijuana. Mood states can affect memory. College students are more likely to remember pleasant events when they're feeling good at the time of recall. Negative events are more likely to be recalled when people are feeling sad or angry. These mood congruency effects are strongest when people try to recall personally meaningful episodes. The more meaningful the experience, the more likely it is that the memory has been colored by their mood.
Explain the characteristics and coding of short-term memory (STM). Discuss the relationship between short-term memory and working memory.
Encoding information in STM is much more elaborate and varied than encoding in the sensory registers. Acoustic encoding (by sound) seems to dominate. This conclusion comes from research on the mistakes people make when encoding information in STM, which tend to involve the substitution of similar sounds. Studies in several cultures have also shown that items are more difficult to remember if they sound similar. Information in STM also can be encoded visually, semantically, and even kinesthetically (in terms of physical movements). STM is a component of working memory, and together these memory systems allow us to do many kinds of mental work. Working memory has at least two components: maintenance (holding information in STM) and manipulation (working on that information. Short-Term Memory (STM) - A stage of memory in which information normally lasts less than 20 seconds; a component of working memory. Working Memory - Memory that allows us to work with, or manipulate, information being held in STM.
Define and give examples of episodic, semantic, and procedural memories.
Episodic Memory: Memory for events in one's own past. Ex. It is a memory of an episode in your life. What you had for dinner yesterday, what you did last summer, or whether you've already told someone a story. Semantic Memory: Contains generalized knowledge of the world that does not involve memory of a specific event. Ex. The fact that twelve items make a dozen. Procedural Memory: A type of memory containing information about how to do things. Ex. Riding a bike, folding a map, or playing golf. It often consists of a sequence of movements that are difficult or impossible to put into words. Episodic Memory - Memory for events in one's own past. Procedural Memory - A type of memory containing information about how to do things.
Define and give examples of explicit and implicit memories.
Explicit: Information retrieved through a conscious effort to remember something. Ex. Where you went for vacation. Implicit: The unintentional recollection and influence of prior experiences. Ex. One can solve a puzzle faster if they've done it before. Explicit Memory - Information retrieved through a conscious effort to remember something. Implicit Memory - The unintentional recollection and influence of prior experiences.
Define and describe Ebbinghaus's method of savings.
He began the systematic study of memory and forgetting in the late 1800s, using only his own memory as his laboratory. He read aloud a list of nonsense syllables at a constant pace and then tried to recall them. He devised a special relearning method to measure how much he forgot over time. He compared the number of repetitions it took him to leans a list of items and the number of trials needed to relearn the same list late. Any reduction in the number of relearning trials represents the savings from one learning to the next. If it took Ebbinghaus ten trials to learn a list and another ten trials to relearn it, there would be no savings. Forgetting would have been complete. If it took him ten trials to learn the list and only five trials to relearn it, there would be a savings of 50 percent. Psychologists now know from the method of savings that information about everything from algebra to bike riding is often retained for decades. Relearning Method - A method for measuring forgetting.
Define the tip-of-the-tongue phenomenon.
In a typical experiment on this phenomenon, participants listen to dictionary definitions and then are asked to name the word being defined. If they can't recall the correct word, they are asked if they can recall any feature of it, such as its first letter or how many syllables it has. Most people experience the tip-of-the-tongue phenomenon about once a weak; older people tend to experience it more often than younger people. This is a type of incomplete knowledge.
Describe the semantic network theory of memory.
In general, semantic network theories suggest that information is retrieved from memory through the principle of spreading activation. When you think about some concept, it becomes activated in the network and this activation begins to "spread" down all the paths that are related to it. Because of the tight organization of semantic networks and the speed at which activation spreads through them, we can gain access to an enormous body of knowledge about the world quickly and effortlessly. We can retrieve not only facts we have learned from others but also knowledge that allows us to draw our own conclusions and inferences. Spreading Activation - In semantic network theories of memory, a principle that explains how information is retrieved.
Define the levels-of-processing model of memory. Define maintenance and elaborative rehearsal and explain how these concepts relate to the levels-of-processing model.
Levels-of-processing Model of Memory: A model that suggests that memory depends on the degree or depth to which we mentally process information. Maintenance Rehearsal: A memorization method that involves repeating information over and over to keep it in memory. Elaborative Rehearsal: A memorization method that relates new information to information already stored in memory. The levels-of-processing memory model suggests that memory depends on the extent to which you encode and process information when you first encounter it. For example, the task of remembering a phone number you just heard on the radio. If you were unable to write it down, you would probably repeat the number over and over to yourself until you could find a pen or get to your phone. This repetition process is called maintenance rehearsal. It can be effective for encoding information temporarily, but what if you need to remember something for hours, months, or years? In the case, you would be better off using elaborative rehearsal, a process in which you relate new material to information you already have stored in memory. According to the levels-of-processing model of memory, the reason that elaborative rehearsal improves memory is that when you use elaborative rehearsal you process material more "deeply." The more you think about new information, organize it, and relate it to something you already know, the "deeper" the processing and the better your memory of the information becomes. Levels-of-Processing Model of Memory - A model that suggests that memory depends on the degree or depth to which we mentally process information. Maintenance Rehearsal - A memorization method that involves repeating information over and over to keep it in memory. Elaborative Rehearsal - A memorization method that relates new information to information already stored in memory.
Discuss explanations for forgetting.
One process is described by decay theory, which suggests that information gradually disappears from memory. Decay occurs in memory in much the same way that the inscription on a ring or bracelet wears away and fades over time. Through interference, either the storage or the retrieval of information is impaired by the presence of other information. Interference might occur because one piece of information actually displaces other information, pushing it out of memory. It might also occur because one piece of information makes storing or recalling other information more difficult. The memory for an item in STM decreases consistently over the course of about 18 seconds if it isn't rehearsed or thought about. So decay appears to play the main role in forgetting in STM. But interference through displacement can also be operating. Displacement is one reason why the phone number you just looked up is likely to drop out of STM if you read another number immediately afterward. Rehearsal prevents displacement by continually reentering the information in STM. Forgetting from LTM appears to be more directly tied to interference. Sometime the interference is due to retroactive inhibition, in which learning new information interferes with our ability to recall older information. Interference can also occur because of proactive inhibition, a process by which old information interferes with our ability to learn or remember new information. Putting more and more information in LTM may be like putting more and more items in a suitcase or a refrigerator. Although none of the items disappears, it becomes increasingly difficult to find the one you are looking for. Decay Theory - A description of forgetting as the gradual disappearance of information from memory. Interference - The process through which storage or retrieval of information is impaired by the presence of other information. Retroactive Inhibition - A cause of forgetting whereby new information placed in memory interferes with the ability to recall information already in memory. Proactive Inhibition - A cause of forgetting whereby previously learned information interferes with the ability to remember new information.
Explain the techniques for improving your memory.
One way to improve your memory is the use of mnemonic strategies. They are ways to put information into an organized framework in order to remember it more easily. Verbal organization is the basis for many mnemonic strategies. You can link items by weaving them into a story, a sentence, or a rhyme. One simple but powerful mnemonic strategy is called the method of loci, or the "method of places." To use this method, first think about a set of familiar locations. Use your home, for example. You might imagine walking through the front door, around all four corners of the living room, and through each of the other rooms. Imagine that each item you want to remember is in one of these location. Creating vivid or unusual images of how the items appear in each location seems to be particularly effective. Whenever you want to remember new images using the same locations in the same order. Remembering lists of items: use mnemonic strategies/look for meaningful acronyms/try the method of loci. Remembering textbook material: follow the PQ4R system/allocate your time to allow for distributed practice/read actively, not passively/test yourself repeatedly as you read. Taking lecture notes: takes notes, but record only the main points/think about the overall organization of the material/review your notes as soon after the lecture as possible in order to fill in missing points. Studying for exams: write a detailed outline of your lecture notes rather than passively reading them. Mnemonic Strategies: Methods for organizing information in order to remember it.
Describe how PDP memory models explain the formation of constructive memories.
PDP models of memory offer one way of explaining how semantic and episodic information become integrated in constructive memories. PDP models suggest that newly learned facts later our general knowledge of the world. In these network models, learned associations between specific facts come together. PDP networks also produce spontaneous generalizations. Spontaneous generalizations are obviously helpful, but they can also create significant errors if the network is based on limited or biased experience with a class of objects or people.
Define retrieval cues and encoding specificity principle.
Retrieval Cues - Stimuli that allow or help people to recall information. Encoding Specificity Principle - A principle stating that the ability of a cue to aid retrieval depends on how well it taps into information that was originally encoded.
Define sensory memory and sensory registers.
Sensory Memory - A type of memory that is very brief but lasts long enough to connect one impression to the next. Sensory Registers - Memory systems that briefly hold incoming information.
Explain the characteristics and coding of long-term memory (LTM).
Some information is encoded into LTM even if we make no conscious effort to memorize it. However, putting information into LTM is often the result of more elaborate and more conscious processing that usually involves semantic encoding. Semantic encoding often leaves out details in favor of the more general underlying meaning of the information. When people encode the general meaning of information they hear or read, they can make mistakes about the details. People encode into LTM not only the general meaning of information but also what they think and assume about that information. People encode the general meaning of visual stimuli rather than specific details. Long-Term Memory (LTM) - The stage of memory that researchers believe has an unlimited capacity to store new information.
Describe the differences between STM and LTM.
Some psychologists argue the STM and LTM have different features and obey different laws. Evidence that information is transferred from STM to a distinct storage system comes primarily from experiments on recall. You can conduct your own recall experiment by reading aloud a list of words at a slow pace. After reading the list just once, look away and write down as many of the words as you can. Memory researchers have found that recall tends to be very good for the first 2 or 3 words in a list. This result is called primacy effect. The probability of recall decreases for words in the middle of the lists and then rises dramatically for the last few words. The ease of recalled words near the end of the list is called the recency effect. The primacy effect may reflect the rehearsal that puts early words into LTM. The recency effect may occur because the last few words are still in STM when you try to recall the list. Primacy Effect - A characteristic of memory in which recall is particularly good for the first two or three items in a list. Recency Effect - A characteristic of memory in which recall is particularly good for the last few items in a list.
Discuss the storage capacity and duration of short-term memory.
The "magic number," which is seven plus or minus two, appears to be the immediate memory span or capacity of STM, at least for most adults in laboratory settings. In addition, the "magic number" refers not only to discrete elements, such as words or digits, but also to chunks, meaningful groupings of information that are produced by a process called chunking. Unless you do something to retain a piece of information, that information in STM is soon forgotten. This feature of STM is adaptive because it gets rid of a lot of useless information; indeed, there are rare cases of people whose inability to forget interferes with their ability to concentrate. The Brown-Peterson distractor technique revealed that after only 18 seconds, participants could remember almost nothing from the activity. Evidence from other such experiments also suggests that unrehearsed information can be held in STM for no more than about 18 seconds. Immediate Memory Span - The maximum number of items a person can recall perfectly after one presentation of the items. Chunking - Organizing individual stimuli so that they will be perceived as larger units of meaningful information. Brown-Peterson Distractor Technique - A method for determining how long unrehearsed information remains in STM.
Describe the storage capacity of long-term memory. Discuss the studies illustrating the distortion of long-term memories.
The capacity of LTM is extremely large. Many psychologists believe that it is literally unlimited. People store vast quantities of information in LTM that can be remembered remarkably well after long periods of time. But LTM is also subject to distortion. Students tested on their memories of 9/11 were not entirely correct. Most of the students whose memories had be substantially distorted over time were unaware that this distortion had occured. In fact, they were very confident that their reports were accurate.
Explain the basic memory processes.
The three basic processes are encoding, storage, and retrieval. First, information must be put into memory, a step that requires encoding. Encoding is a process that puts information to be remembered into a form that our memory system can accept and use. The second basic memory process is storage. Storage refers to the holding of information in your memory over time. The third memory process - retrieval - occurs when you find information stored in memory and bring it into consciousness. Encoding - The process of putting information into a form that the memory system can accept and use. Storage - The process of maintaining information in the memory system over time. Retrieval - The process of finding information stored in memory.
Describe the different models of memory transfer-appropriate processing, parallel distributed processing (PDP), and information-processing. Name the three stages of processing.
Transfer-Appropriate Processing: It suggests that another critical factor is the match between how we try to retrieve information and how we originally encoded it. How well the encoding method aligns with the retrieval task is just as important as the depth of processing. Parallel Distributed Processing: These models suggest that new experiences do more than provide specific facts that are stored and later retrieved one at a time. Those facts are also combined with what you already know so that each new experience changes your overall understanding of the world and how it operates. PDP models of memory see each unit of knowledge as connected to every other unit. The connections between units become strong as they are experienced together more frequently. Your PDP network allows you to quickly and efficiently draw inferences and generalizations about the world, including how you can get information that is not already in you knowledge base. Information Processing: It suggests that for information to be firmly implanted in memory, it must pass through three states of mental processing sensory memory, short-term memory, and long-term memory. Sensory Memory - Briefly retains the information picked up by the sensory organs (information lost after about one second). Short-Term Memory - Temporarily holds information in consciousness (information stored for about 18 seconds). Long-Term Memory - Can retain information for long periods of time, often for life. PDP Models of Memory - Memory models in which new experiences are seen as changing one's overall knowledge base. Transfer-Appropriate Processing Model of Memory - A model that suggests that memory depends on how the encoding process matches up with what is later retrieved. Information-Processing Model of Memory - A model that suggests that information must pass through sensory memory, short-term memory, and long-term memory in order to become firmly embedded in memory.