I. Memory: Processes, Models, Sensory Memory, Short-Term Memory A. Memory processes
1. Memory and Its Processes
Memory – an active system that receives information from the senses, organizes and alters it as it stores it away, and then retrieves the information from storage. Processes of Memory:
Encoding – converting sensory information into a form that is usable in the brain’s storage systems. Storage – holding onto information for some period of time. Retrieval – getting information that is in storage into a form that can be used. B. Models of memory
1. Models of Memory
assumes the processing of information for memory storage is similar to the way a computer processes memory in a series of three stages (encoding storage retrieval) [graphic] Three-Stage Process of Memory
Information enters through the sensory system, briefly registering in sensory memory. Selective attention filters the information into short-term memory, where it is held while attention (rehearsal) continues. If the information receives enough rehearsal (maintenance or elaborative), it will enter and be stored in long-term memory. Levels-of-processing model
assumes information that is more “deeply processed,” or processed according to its meaning rather than just the sound or physical characteristics of the word or words, will be remembered more efficiently and for a longer period of time. The deeper we process information, the more meaning it will have for us, the longer it will stay with us, and the easier it will be to pull it up from long-term memory Parallel distributed processing (PDP) model
memory processes are proposed to take place at the same time over a large network of neural connections. C. Sensory memory
1. Sensory Memory
Sensory memory – the very first stage of memory, the point at which information enters the nervous system through the sensory systems. [graphic]
Iconic Memory Test
Sample grid of letters for Sperling’s test of iconic memory. To determine if the entire grid existed in iconic memory, Sperling sounded a tone associated with each row after the grid’s presentation. Participants were able to recall the letters in the row for which they heard the tone. The graph shows the decrease in the number of letters recalled as the delay in presenting the tone increased. Iconic memory – visual sensory memory, lasting only a fraction of a second (about ¼ to ½ a second). Capacity – everything that can be seen at one time.
Duration – information that has just entered iconic memory will be pushed out very quickly by new information, a process called masking. Eidetic imagery – the rare ability to access a visual memory for 30 seconds or more. Echoic memory – the brief memory of something a person has just heard. Capacity – limited to what can be heard at any one moment and is smaller than the capacity of iconic memory Duration – lasts longer that iconic — about 2 to 4 seconds D. Short-term memory
1. Short-Term Memory
Short-term memory (STM) (working memory) – the memory system in which information is held for brief periods of time while being used. Selective attention – the ability to focus on only one stimulus from among all sensory input. Digit-span test
Conclusions are that the capacity of STM is about seven items or pieces of information, plus or minus two items, or from five to nine bits of information. “magical number” = 7 +/- 2
[graphic] Digit-Span Test
Instructions for the digit-span test: Listen carefully as the instructor reads each string of numbers out loud. As soon as each string is ended (the instructor may say “go”), write down the numbers in the exact order in which they were given. Chunking – bits of information are combined into meaningful units, or chunks, so that more information can be held in STM. To recall information, we break up the chunks into smaller units in a reverse chunking process Duration of STM – lasts from about 12 to 30 seconds without
rehearsal. STM is susceptible to interference (e.g., if counting is interrupted, have to start over).
Maintenance rehearsal – practice of saying some information to be remembered over and over in one’s head in order to maintain it in short-term memory (STMs tend to be encoded in auditory form). Elaborative rehearsal – a method of transferring information from STM into LTM by making that information meaningful in some way Combining new information with already-known information
II. Long-Term Memory: Types of Long-Term Memory, Organization of Memory, Retrieval A. Types of long-term memory
1. Long-Term Memory
Long-term memory (LTM) – the system of memory into which all the information is placed to be kept more or less permanently. Information stored on basis of meaning and importance
Capacity: theoretically limitless
Duration: relatively permanent
2. Types of LTM
Procedural (nondeclarative) memory – memory for skills, procedures, habits, and conditioned responses. Declarative memory – type of long-term memory containing information that is conscious and known (memory for facts). 3. Procedural (Nondeclarative) LTM
Skills that people know how to do.
These memories are known as implicit memory – they are not conscious but are implied to exist because they affect conscious behavior. Also include emotional associations, habits, and simple conditioned reflexes that may or may not be in conscious awareness. [graphic] Tower of Hanoi
The Tower of Hanoi is a puzzle that is solved in a series of steps by moving one disk at a time. The goal is to move all of the disks from peg A to peg C; the rules are that a larger disk can not be moved on top of a smaller one and a disk can not be moved if there are other disks on top of it. Amnesia patients were able to learn the procedure for solving the puzzle but could not remember that they knew how to solve it. 4. Declarative LTM
All the things that people know.
Semantic memory – memory containing general knowledge, such as knowledge of language and information learned in formal education. Episodic memory – memory containing personal information not readily available to others, such as daily activities and events. Semantic and episodic memories are forms of explicit memory – memory that is consciously known. [graphic] Types of Long-Term Memories
Long-term memory can be divided into declarative memories, which are factual and typically conscious (explicit) memories, and nondeclarative memories, which are skills, habits, and conditioned responses that are typically unconscious (implicit). Declarative memories are further divided into episodic memories (personal experiences) and semantic memories (general knowledge). B. How memory is organized
1. Organization of Memory
LTM organized in terms of related meanings and concepts.
Semantic network model – assumes information is stored in the brain in a connected fashion, with concepts that are related stored physically closer to each other concepts that are not highly related. [graphic] An Example of a Semantic Network
In the semantic network model of memory, concepts that are related in meaning are thought to be stored physically near each other in the brain. In this example, canary and ostrich are stored near the concept node for “bird,” whereas shark and salmon are stored near “fish.” But the fact that a canary is yellow is stored directly with that concept. 2. Cues to Help Remember
Retrieval cue – a stimulus for remembering.
Encoding specificity – the tendency for memory of information to be improved if related information available when the memory is first formed is also available when the memory is being retrieved. State-dependent learning – memories formed during a particular physiological or psychological state will be easier to recall while in a similar state. [graphic] Recall of Target Words in Two Contexts
The retrieval of words learned while underwater was higher when the retrieval also took place underwater. Similarly, words learned while out of the water (on land) were retrieved at a higher rate out of the water. Reproduced with permission from the British Journal of Psychology, © The British Psychology Society. 3. Formation of LTMs
Consolidation – the changes that take place in the structure and functioning of neurons when an memory is formed. Hippocampus – area of brain responsible for the formation of LTMs. Case of H.M. “…remembering is more like making up a story than it is like reading one printed in a book.” Constructive processing – retrieval of memories in which those memories are altered, revised, or influenced by newer information. Hindsight bias – the tendency to falsely believe, through revision of older memories to include newer information, that one could have correctly predicted the outcome of an event. 4. Automatic Encoding and Flashbulb Memories
Automatic encoding – tendency of certain kinds of information to enter long-term memory with little or no effortful encoding. Flashbulb memories – type of automatic encoding that occurs because an unexpected event has strong emotional associations for the person remembering it. C. Memory retrieval
Recall – type of memory retrieval in which the information to be retrieved must be “pulled” from memory with very few external cues. Retrieval failure – recall has failed (at least temporarily). Tip of the tongue phenomenon.
[graphic] Mr. Total Recall
Serial position effect – tendency of information at the beginning and end of a body of information to be remembered more accurately than information in the middle of the body of information. Primacy effect – remember information at the beginning of a body of information better than the information that follows. Recency effect – remember information at the end of a body of information better than the information ahead of it. [graphic] Serial Position Effect
In the serial position effect, information at the beginning of a list will be recalled at a higher rate than information in the middle of the list (primacy effect), because the beginning information receives more rehearsal and may enter LTM. Information at the end of a list is also retrieved at a higher rate (recency effect), because the end of the list is still in STM, with no information coming after it to interfere with retrieval. 2. Recognition
Recognition – the ability to match a piece of information or a stimulus to a stored image or fact. False positive – error of recognition in which people think that they recognize some stimulus that is not actually in memory. 3. Eyewitness Testimony
Elizabeth Loftus study.
Showed that what people see and hear about an event after the fact can easily affect the accuracy of their memories of that event. Eye witness testimony not always reliable.
III. Forgetting: Theories of Forgetting, Medical Factors
A. Theories of forgetting
1. Memory Retrieval Problems
Misinformation effect – the tendency of misleading information presented after an event to alter the memories of the event itself. 2. Reliability of Memory Retrieval
False memory syndrome – the creation of inaccurate or false memories through the suggestion of others, often while the person is under hypnosis. Evidence suggests that false memories cannot be created for just any kind of memory. The memories must at least be plausible.
3. Forgetting – Ebbinghaus
Curve of forgetting – a graph showing a distinct pattern in which forgetting is very fast within the first hour after learning a list and then tapers off gradually. Distributed practice will produce better retrieval than massed practice [graphic] Curve of Forgetting
Ebbinghaus found that his recall of words from his memorized word lists was greatest immediately after learning the list but rapidly decreased within the first hour. After the first hour, forgetting leveled off. 4. Forgetting: Encoding Failure
Encoding failure – failure to process information into memory. [graphic] Which Penny Is Real?
Most people do not really look at the face of a penny. Which of these pennies represents an actual penny? The answer can be found in the text book. 5. Forgetting: Memory Trace Theory
Memory trace – physical change in the brain that occurs when a memory is formed. Decay – loss of memory due to the passage of time, during which the memory trace is not used. Disuse – another name for decay, assuming that memories that are not used will eventually decay and disappear. 6. Forgetting: Interference Theory
Proactive interference – memory retrieval problem that occurs when older information prevents or interferes with the retrieval of newer information. Retroactive interference – memory retrieval problem that occurs when newer information prevents or interferes with the retrieval of older information. [graphic] Proactive and Retroactive Interference
If a student were to study for a French exam and then a Spanish exam, interference could occur in two directions. When taking the Spanish exam, the French information studied first may proactively interfere with the learning of the new Spanish information. But when taking the French exam, the more recently studied Spanish information may retroactively interfere with the retrieval of the French information. [graphic] Reasons for Forgetting
B. Medical factors affecting retrieval
Retrograde amnesia – loss of memory from the point of some injury or trauma backwards, or loss of memory for the past. Anterograde amnesia – loss of memory from the point of injury or trauma forward, or the inability to form new long-term memories (“senile dementia”). Case of H.M. Infantile amnesia – the inability to retrieve memories from much before age 3. Autobiographical memory – the memory for events and facts related to one’s personal life story (usually after age 3). 2. Alzheimer’s Disease
The primary memory difficulty in Alzheimer’s is anterograde amnesia, although retrograde amnesia can also occur as the disease progresses. There are various drugs in use or in development for use in slowing or stopping the progression of Alzheimer’s disease.