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Transcript of Chp 7
What is stored in your head is not just facts and figures but also the experiences that make up your life.
Memory lets us have a past and a future. Our lives can be very hard without it.
It is an ability we develop in childhood. Before it is developed, you do not even know who you are.
Your memory is you.
Since late 1960s, with the rise of cognitive psychology, psychologists viewed memory as a form of information processing as it occurs in computers.
Just like a computer, we receive the information, process, store and retrieve it.
Even though now psychologist believe that there are multiple memory systems that do not follow these stages, information processing models have been very influential in memory studies and the terminology is still widely used.
Role of Attention
What determines what gets into memory? "Attention does."
And attention can viewed as a flashlight on experience. It makes us focus on something and makes it memorable.
It might be an automatic, effortful, or involuntary process.
Our attention is limited. As a result our memory is limited, too.
Change blindness: it occurs due to a failure to store the information in
the first place or to a failure to compare the relevant information.
Levels of Processing & Elaboration
Attention is critical for encoding of memories, but how you attend also matters in creating lasting memory codes.
Semantic coding enriches the encoding process and improves the memory.
Semantic encoding is supported by elaboration-thinking how that information is related to other things, thinking about one or more examples on that idea.
Self-relevant examples and visual cues increase your chances to remember even more.
Sensory memory allows us store sensory information briefly.
Sensory memory is a remainder in your senses.
When you see a flash of lightning. You might see an afterimage. That afterimage is your sensory memory.
Your sensory memory is somewhat longer for sounds. So as somebody is talking to you even if you're not paying attention you'll store a few seconds of what they're saying.
Short term memory can maintain information for up to 20 seconds; it then disappears unless you think about it or repeat it.
Short-term memory is also limited in the number of items it can hold: 7 items, plus or minus two.
However, you can increase the capacity of your short term memory by organizing, grouping this information into larger units. This organization is known as chunking. Chunking works in two ways:
First, memory span is limited to seven or less items; but items can be letters, numbers,
words or concepts.
Second, meaningful units are easier to remember than nonsense units. How much you
know affects how much you memorize--how much you could store in memory. This is
the expertise effect.
It became apparent that short-term memory is not a single storage system but rather an active processing unit that deals with multiple types of information, such as sounds, images, and ideas. Most theorists today use the concept of working memory instead of short-term memory.
The information coded meaningfully or semantically and rehearsed becomes long-term memory.
Long-term memory is an unlimited capacity store that can hold information over long periods of times, ranging from a few days to many years.
However, information in long term memory becomes less detailed and complete with time and they are often inaccurate.
By the 80’s, memory started to be seen as a process that involves a number of interacting systems.
Although the systems share a common function- to retain and use information- they encode and store different types of information in different ways.
Scientists do not yet agree on the number of human memory systems. Some classifies according to the process (explicit vs. implicit), while some refers to the content (declarative vs. procedural) of memory in their classification.
-intentional recollections of previous experiences
- Can be accessed directly, and best assessed with recall or recognition measures of retention.
-remembering without deliberate effort
-Studies on implicit memories started a few decades ago with the studies conducted on people with memory disorders.
-Even though these patients cannot remember the words with conscious efforts, when asked indirectly (when words are primed) they are able to recollect them.
-involves motor skills, habits, actions and operations.
-Examples of procedural memory are riding a bike, playing piano, playing tennis, driving a car
It is the factual information, knowledge that can be declared.
A further distinction in declarative memory was suggested and it is divided into:
Our personal past experiences such as the day you started university, or your last summer vacation.
Episodic memory holds a chronological order of personal experiences. This gives us the opportunity for time travel, both in the past and future.
Our knowledge of general facts independent of personal experiences such as there are twelve months in a year; Ottawa is the capital city of Canada.
It is not tied to the time when the information is learned
The main aim of encoding and storing information is to recall it when needed.
First of all, the information should be available and accessible when we are trying to recall.
How knowledge is represented and organized in memory?
Given the vast amount of material in memory, it is amazing how quickly we can search for and obtain needed memories from storage.
For this to occur, the information needs to be organized in some way.
-Clustering: grouping similar items in a category
-Schemas: mental set/representations based on our previous experiences about a particular object or an event
-Conceptual hierarchies: multilevel classification system based on common properties.
Each unit of information in the network is known as a node.
Semantically related items (nodes) are linked together.
These connections between the items form a semantic network.
Once a node is activated in working memory, it will also activate related nodes in the long-term memory. This will increase the ease of access to that material and facilitate the retrieval.
Recalling can be still a hard task for us even with an organized memory system.
Another important factor in retrieval, in accessing information from long-term memory is a retrieval cue. When we are given retrieval cues, it is easier to recognize or identify the info.
Partial information may be a retrieval cue:
“What is the capital city of Manitoba?”
Retrieval cue: It starts with "w"
Most people will find it easier to remember that Winnipeg is Manitoba’s capital, if they are given the first letter of the answer.
Contextual information may be a retrieval cue, as well. Recollection of information is also facilitated when recall situation is similar to encoding situation.
Is everything we recall accurate?
Flashbulb memories: vivid, detailed memories for the circumstances when you first learned about a surprising or very important event.
Research showed even memories for such important events might be inaccurate and change with time.
The most well-known effect in the reconstruction of memories is misinformation effect. It occurs when people’s recall of an event they witnessed is altered by post-event misleading information.
One reason that we are very likely to reconstruct our memories is that we cannot remember or identify the source of the information. We cannot remember the origin of the memories and start to make attributions or assumptions about the source of the information.
When very important decisions are given such as accusing someone with a serious crime, accuracy of memories becomes a major issue.
After the findings of psychologists on the accuracy of memory and the malleable nature of memory, many practices were changed in the criminal system and cautions are taken.
Still, many people suffer from the consequences of errors in eyewitness testimonies.
Why do we forget?
Even though it is adaptive to be able to forget at certain times, it is not very adaptive to forget important information, so scientists have been trying to understand why we forget.
The first studies about forgetting were back in 1885, conducted by Ebbinghaus. According to Ebbinghaus, forgetting occurs very fast.
Fortunately, other studies showed that we do not forget the meaningful and autobiographical information that fast.
Also, the way we measure forgetting affects the results as well. Retention rate is higher in recognition measurements (such as multiple choice questions) compared to recall measurements (such as essay questions).
This type of forgetting occurs when we fail to encode the information at the first place. While trying to remember, we actually try to recall information that has never been effectively coded.
Passage of time and physiological decay of our minds produce forgetting. Every time we form a memory a memory trace is formed. Over time, this trace disintegrates if it is not used. Decay theory alone cannot explain forgetting in long term memory. Some old memories were found to be more resistant than recent memories.
Your ability to remember something can be impaired by learning more things which are related or similar to it, because certain information interferes with the other information during retention.
Sometimes we cannot remember something due to lack of proper retrieval cues. The information still exists, but without these cues retrieval is unlikely.
Motivated Forgetting (repression):
Final explanation for forgetting comes from Freud. When we do not want to remember unpleasant, painful or embarrassing memories, we unconsciously block the retrieval of these memories.
There is still a big debate going on about the validity of this argument.
Physiology of Memory
We are still trying to understand physiological basis of memory and the chemical code for memory.
We know that:
Memories are not stored in any one specific brain location. Rather, memories are stored in multiple regions of the brain and linked together through memory circuits.
Neural specialization occurs in different brain regions and these regions become responsible for storing different aspects of information.
Biochemistry of Memory
Learning and memory formation occurs by the changes in the release of certain neurotransmitters depending on the experience. These durable changes lead to a stronger or weaker connection between neurons.
Certain drugs and hormonal changes can also affect the release of neurotransmitters and memory formation.
Neural Circuitry of Memory
Researchers think that memories create unique neural pathways to represent a memory.
Studies on Long-term potentiation (LTP) support this argument. In these studies, a high-frequency electrical stimulation given to a neuron produced a long-lasting increase in neural excitability at synapses along a specific neural pathway.
In other words, neurons wire together fire together.
We still do not know which pathway represents which memory.
Anatomy of Memory
These specialized neuron circuits are in different regions of the brain and these brain regions become responsible for storing different aspects of information.
Indeed, different memory systems, such as declarative and procedural memories, use different brain regions.
Hippocampus and nearby structures (hippocampal region) are critical for many types of long-term memory.
Importance of hippocampal region does not come from storing long-term memories but from consolidation of memories. Researchers believe that by consolidation, information is transformed into long-term memories in hippocampal region and then stored and distributed in various areas of cortex.
Another brain region that is important in the formation of emotionally intense memories is amygdala.
Sensory memory allows us store sensory information briefly.
Sensory memory is a remainder in your senses.
If you see a flashlight moving in the dark, you will see an afterimage. That afterimage is your sensory memory.
This brief preservation of sensations in sensory memory gives you additional time to try to recognize stimuli.
Compared to visual sensory memory your sensory memory is somewhat longer for sounds. So as somebody is talking to you even if you're not paying attention you'll store a second of what they're saying.