Memory and its Processes
Memory – system that senses, organizes, alters, stores, and retrieves information
- Encoding – the set of mental operations that people perform on sensory information to convert that 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.
Models of Memory
Information-processing model – model of memory that assumes the processing of information for memory storage is similar to the way a computer processes memory in a series of three stages.
Levels-of-processing model – model of memory that 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.
Parallel distributed processing (PDP) model – a model of memory in which memory processes are proposed to take place at the same time over a large network of neural connections.
Sensory memory – the very first stage of memory, the point at which information enters the nervous system through the sensory systems.
Iconic memory – visual sensory memory, lasting only a fraction of 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
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 – memory test in which a series of numbers is read to subjects in the experiment who are then asked to recall the numbers in order.
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
Chunking – bits of information are combined into meaningful units, or chunks, so that more information can be held in STM.
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).
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).
Long-term memory (LTM) – the system of memory into which all the information is placed to be kept more or less permanently.
Elaborative rehearsal – a method of transferring information from STM into LTM by making that information meaningful in some way.
Types of LTM
Procedural (nondeclarative) memory – type of long-term memory including memory for skills, procedures, habits, and conditioned responses. These memories are not conscious but are implied to exist because they affect conscious behavior.
Declarative memory – type of long-term memory containing information that is conscious and known (memory for facts).
Procedural (Nondeclarative) LTM
Skills that people know how to do.
Also include emotional associations, habits, and simple conditioned reflexes that may or may not be in conscious awareness.
Anterograde amnesia – loss of memory from the point of injury or trauma forward, or the inability to form new long-term memories. Usually does NOT affect procedural LTM.
Procedural memory often called implicit memory – memory that is not easily brought into conscious awareness.
All the things that people know.
- Semantic memory – type of declarative memory containing general knowledge, such as knowledge of language and information learned in formal education.
- Episodic memory – type of declarative 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.
Organization of Memory
LTM organized in terms of related meanings and concepts.
Semantic network model – model of memory organization that assumes information is stored in the brain in a connected fashion, with concepts that are related stored physically closer to each other than retrieval cue a stimulus for remembering.
Cues to Help Remember
Retrieval cue – a stimulus for remembering.
Encoding specificity – the tendency for memory of information to be improved if related information (such as surroundings or physiological state) 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.
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.
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 – tendency to remember information at the beginning of a body of information better than the information that follows.
- Recency effect – tendency to remember information at the end of a body of information better than the information ahead of it.
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.
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.
- Eyewitness testimony not always reliable.
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.
How LTMs Are Formed
“. . . remembering is more like making up a story than it is like reading one printed in a book.”
Constructive processing – referring to the 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.
Memory Retrieval Problems
Misinformation effect – the tendency of misleading information presented after an event to alter the memories of the event itself.
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.
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
Forgetting: Encoding Failure
Encoding failure – failure to process information into memory.
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.
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.
Formation of LTMs
Engram – the physical change that takes place in the brain when a memory is formed.
Consolidation – the changes that take place in the structure and functioning of neurons when an engram is formed.
Hippocampus – area of brain responsible for the formation of LTMs.
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”).
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).
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.