Encoding (memory)

Encoding allows a perceived item of use or interest to be converted into a construct that can be stored within the brain and recalled later from long-term memory.

Using himself as a subject he studied how we learn and forget information by repeating a list of nonsense syllables to the rhythm of a metronome until they were committed to his memory.

[3] This model also suggested that information not present at the time of encoding would be added to memory if it was based on schematic knowledge of the world.

In 1956, George Armitage Miller wrote his paper on how short-term memory is limited to seven items, plus-or-minus two, called The Magical Number Seven, Plus or Minus Two.

In 1974, Alan Baddeley and Graham Hitch proposed their model of working memory, which consists of the central executive, visuo-spatial sketchpad, and phonological loop as a method of encoding.

Various strategies can be applied such as chunking and mnemonics to aid in encoding, and in some cases, allow deep processing, and optimizing retrieval.

According to Baddeley, processing of auditory information is aided by the concept of the phonological loop, which allows input within our echoic memory to be sub vocally rehearsed in order to facilitate remembering.

[18] The hippocampus is responsible for analyzing these inputs and ultimately deciding if they will be committed to long-term memory; these various threads of information are stored in various parts of the brain.

For that to happen, NMDA receptor, which influences the flow of information between neurons by controlling the initiation of long-term potentiation in most hippocampal pathways, need to come to the play.

[18] Positron emission tomography (PET) demonstrates a consistent functional anatomical blueprint of hippocampal activation during episodic encoding and retrieval.

One study used PET to measure cerebral blood flow during encoding and recognition of faces in both young and older participants.

[21] Recent findings in studies focusing on patients with post traumatic stress disorder demonstrate that amino acid transmitters, glutamate and GABA, are intimately implicated in the process of factual memory registration, and suggest that amine neurotransmitters, norepinephrine-epinephrine and serotonin, are involved in encoding emotional memory.

[25] Synaptic plasticity is the ability of the brain to strengthen, weaken, destroy and create neural synapses and is the basis for learning.

This shows that the synaptic modifications that occur can operate either way, in order to be able to make changes over time depending on the current situation of the organism.

[25] A significant short-term biochemical change is the covalent modification of pre-existing proteins in order to modify synaptic connections that are already active.

These changes include new protein synthesis, the formation of new synaptic connections, and finally the activation of gene expression in accordance with the new neural configuration.

In fact, variations within these genes appear to be associated with memory capacity and have been identified in recent human genetic studies.

A study done in 2009 shows encoding success and novelty detection activity within the task-positive network have significant overlap and have thus been concluded to reflect common association of externally oriented processing.

[27] It also demonstrates how encoding failure and retrieval success share significant overlap within the task negative network indicating common association of internally oriented processing.

According to Craik and Lockhart, the encoding of sensory information would be considered shallow processing, as it is highly automatic and requires very little focus.

In general, however previous learning by maintenance rehearsal is not apparent when memory is being tested directly or explicitly with questions like " Is this the word you were shown earlier?"

This effect called context reinstatement was demonstrated by Fisher and Craik 1977 when they matched retrieval cues with the way information was memorized.

An experiment conducted by Morris and coworkers in 1977 proved that successful retrieval was a result of matching the type of processing used during encoding.

[60] Studies have shown that an effective tool to increase encoding during the process of learning is to create and take practice tests.

Using retrieval in order to enhance performance is called the testing effect, as it actively involves creating and recreating the material that one is intending to learn and increases one’s exposure to it.

[61] The benefits of using retrieval practice have been demonstrated in a study done where college students were asked to read a passage for seven minutes and were then given a two-minute break, during which they completed math problems.

Later all participants were given a recall test at various increments (five minutes, 2 days, and one week) after the initial learning had taken place.

Because the items in the memory matrix contain noise in their values, this model can account for incorrect recalls, such as mistakenly calling a person by the wrong name.

There are currently two main computational memory models that can be applied to sequence encoding: associative chaining and positional coding.

Although the models of associative chaining and positional coding are able to explain a great amount of behavior seen for sequence memory, they are far from perfect.