Short Term Memory

Short-Term Memory(STM)


STM is characterized by:

• Capability such that only seven pieces of independent information can be stored
• A brief duration of these items last from 3 to 20 seconds.

How and where Brain stores information

WHERE THE INFORMATION IS STORED IN THE BRAIN

Like hard disc in computers, we have brain to store the information. Mind and memory are stored in it as software. Scientists have done many experiments in finding where exactly this software is stored in brain.

Some of the results are given below :

• Karl Lashley, a behavioral psychologist made different experiments to know about the part of the brain where the memory is stored. In the 1920s, trained rats to find their way through a maze, then made lesions in different parts of the cerebral cortex in an attempt to erase what he called the "engram," or the original memory trace. Lashley failed to find the engram even after placing lesions every possible places in the brain, however the experimental animals are able to solve the maze. He therefore concluded that memories are not stored in any single area of the brain, but are distributed throughout the brain.

• Brenda Milner—proposed that a part of the brain called the hippocampus as being prominent in memory formation. More recently, it was established that the frontal cortex is also involved; current thinking holds that new memories are encoded in the hippocampus and then eventually transferred to the frontal lobes for long-term storage.

Actually the location of a recollection in the brain varies based on how old that recollection is.

Smith and Squire assessed the brain activity associated with the recollection of old and new memories. They functional magnetic resonance imaging (fMRI) to scan 15 patients' brains while they answered 160 questions about news events that took place at different periods of time during the past 30 years. The experiment is quite simple but for it to produce any conclusion is pretty hard tasks, like creating the non visible relation among the memories of different timelines etc., 

Few inferences made:

First, when one is asked to recall any given memory, the brain encodes not only the questions that were asked to cue the retrieval, but also the resulting recollection, so the associated activity could therefore interfere with that which is being assessed.  Second, more recent memories are likely to be richer and more vivid than older ones, so the strength of the fMRI(functional MRI) signal could be related not just to the time at which a recalled event occurred but also to the richness of the participants' recollection of it.

Finally, recalled memories could be strongly associated with their personal life, which make them easier to be remembered.

Smith and Squire therefore designed their experiments so that they could assess the effects  of the age of a memory independently of both the encoding of the test questions and richness of the recollection of the memory. At the beginning of the task, the researchers gave a set of questions and asked the patients whether or not they knew the answer. And about few minutes later the patients were asked three questions about each news event. 

• First, they were asked to recall the question that had been asked about the event (to know how well they had encoded the information). 
• Then, they were asked the answer to that question (to know the accuracy of recall) and, 
• finally, how much they knew about each of the events (to know the richness of each memory).

 In cognitive psychology, there is one memory system, but it is normally divided into three functions for storage (Anderson, 2000): sensory, short-term often called working), and long- term (often called permanent).

Sensory Memory: The sensory memory retains an exact copy of what is seen or heard

(visual and auditory). It only lasts for a few seconds, while some theorize it last only 300

milliseconds. It has unlimited capacity. It is like when you move on the road you see many things may be humans, animals, objects or even the feel you get, they are momentary and they reach the next level(STM) if it catches your interest like a beautiful girl. 

Short-Term Memory (STM) - Selectively few information enters into this stage. STM is most often stored as sounds, especially in recalling words, but may be stored as images. It works basically the same as a computer's RAM (Random Access Memory) in that it provides a working space for short computations and then transfers it to other parts of the memory system or discards it. It is thought to be about seven bits in length, that is, we normally remember seven items. STM is vulnerable to interruption or interference.Read more..

Long-Term Memory - This is something like a permanent storage. Information is stored on the basis of meaning and importance. There is more to this. Read more..

Tags: Short Term Memory, Log term memory, How brain store the information, brain, memory, chunking, improve memory, improve memory power, Experiments on rats, lesion

Long Term Memory

Check some related posts:

• Short Term Memory
• How information is stored in brain

Long-Term Memory (LTM)


The knowledge we store in LTM affects our perceptions of the world, and influences what information in the environment we attend to. LTM gives the framework and we develop with more knowledge. It takes the priority over the STM and other memories, that is where people make their decisions. The limit of LTM is not known.

Schemas are mental models of the world. Information in LTM is stored in interrelated networks of these schemas. These, in turn, form intricate knowledge structures. Related schemas are linked together and loading one schema retrieves all the related schemas. This is how we recall relevant knowledge when similar information is presented. These schemas guide us by diverting our attention to relevant information and allow us to ignore the rest.

Since LTM storage is organized into schemas, instructional designers activate existing schemas and present it in a structured and interesting manner. This can be done in a many ways, including graphic organizers, movies, etc.


LTM also has a strong influence on perception through top-down processing - our prior knowledge affects how we perceive sensory information. We interpret an experience by the expectations and satisfaction attained. We develop bias from this. Also, most optical illusions take advantage of this fact.
An important factor for retention of learned information in LTM is rehearsal that provides transfer of learning.



Tags:Brain, Long term memory, short term memory, how brain store information,