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--- outreach:formsofforgetting [2023/07/16 15:09] – [Trace Decay] ohardt
+++ outreach:formsofforgetting [2024/07/23 14:15] (current) – ohardt
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 ====== Forgetting processes ======
-There are two phases in research on forgetting.  During the first phase, lasting until the first decade of the 21st century, forgetting was largely regarded as a shortcoming of memory, as a malfunction of actual memory processes, such as memory formation or retrieval.  There were some notable exceptions to this view, for example the idea prominently formulated by Freud that some forgetting results from targeted repression, or inhibition, of memory.  In the laboratory, this form of forgetting has been studied with intentional forgetting tasks, or directed forgetting, where human participants are instructed to forget some of the material presented to them, while remembering others.  Outside this context, however, forgetting was not understood as a true function of the brain, as the result of innate, or constitutive, processes that are part of normal brain function.
+There are two phases in research on forgetting.  During the first phase, lasting until the first decade of the 21st century, forgetting was largely regarded as a shortcoming of memory, as a malfunction of actual memory processes, such as memory formation or retrieval.  There were some notable exceptions to this view, for example the idea prominently formulated by Freud that some forgetting results from targeted repression, or inhibition, of memory.  In the laboratory, this form of forgetting has been studied with intentional forgetting tasks, or directed forgetting, where human participants are instructed to forget some of the material presented to them, while remembering others.  Outside this context, however, forgetting was not understood as a true function of the brain, as the result of innate, or constitutive, processes that are part of normal brain function.  Forgetting was not seen as adaptive behaviour, but quite the opposite, and even in Freud's view that saw forgetting as a function of the mind, repression eventually brought people onto his couch.
 This view changed during the second phase, marked by discoveries of mechanisms in the brain dedicated to erase memories.  This was observed relatively independent of each other in invertebrate and vertebrate animals.  In fruit flies, it was found that certain neurons use dopamine signalling to eliminate memories, so that increasing the activity of these neurons accelerated forgetting, while blocking their activity prevented forgetting.  About the same time it was found in rodents that the natural loss of memory over days can be prevented by interrupting the removal of parts of neurons required for neurons to communicate with each other (receptors).  Notably, this form of removal requires a signal initiating it, and it was later found that other receptors may provide this signal.  Just as in the fruit fly, increasing the activity of these receptors sped up natural forgetting, while blocking their activity preserved memory from obliteration.  The conclusion from these findings is that certain forms of forgetting are not the result of failures of other memory mechanisms, but the outcome of dedicated processes, which are now collectively called //active forgetting// processes, to distinguish them from the view that dominated the first phase of research into forgetting.
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 ==== Trace Decay ====
-The idea that memories result from structural changes has been proposed already by Réné Descartes. Using the analogy of a wax tablet, he argued that memories are akin to markings engraved on malleable, plastic matter.  Just as imprints on a wax tablet, experiences leave their traces on the mind, and just like the traces on a wax tablet, these impressions may fade over time.  It is perhaps no accident that words referring to memory resonate this concept.  We are told to //mark// what someone said, we claim that something is //stuck// in our mind, we note that an event left an //impression// on us, and so forth.  The idea that memory may result from structural changes to mind or brain is intuitive, as we have many examples of long-lasting records of human thought in the engravings left behind on rocks and stones by ancient cultures.
+The idea that memories result from structural changes has been proposed by Plato. Using the analogy of a wax tablet, he argued that memories are akin to markings engraved on malleable, plastic matter.  Just as imprints on a wax tablet, experiences leave their traces on the mind, and just like the traces on a wax tablet, these impressions may fade over time.  It is perhaps no accident that words referring to memory resonate this concept.  We are told to //mark// what someone said, we claim that something is //stuck// in our mind, we note that an event left an //impression// on us, and so forth.  The idea that memory may result from structural changes to mind or brain is intuitive, as we have many examples of long-lasting records of human thought in the engravings left behind on rocks and stones by ancient cultures.
 In 1913, Edward Thorndike suggested trace decay as a reason why we forget.  His idea was formulated in behaviourist terminology, arguing that if we talk about memory, we are talking about the fact that a certain situation (or stimulus) produces a certain response.  This is possible because the stimulus is connected to the response, which allows the former to trigger the latter.  Forgetting, according to Thorndike, serves an adaptive function.  Specifically, he proposed that when the connection between a stimulus and a response is not activated for a certain time, the strength of this connection is decreased, and, eventually, the stimulus can no longer produce the response.  This version of trace decay is often summarized as the principle "if you don't use it, you loose it", and Thorndike may have found this view intuitive from his practice as an educator, where regular repetition of learned material promotes its long-term retention.  Consequently, he named his explanation for forgetting the "Law of Disuse".