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Short term memory decays and high presentation rates hurry this decay: The Murdock free recall experiments interpreted in the Tagging/Retagging model

By Dr. Eugen Tarnow


I show that the curious free recall data of Murdock (1962) can be explained by the Tagging/Retagging model of short term memory (Tarnow, 2009 and 2008) in which a short term memory item is a tagged long term memory item. The tagging (linear in time) corresponds to the synaptic process of exocytosis and the loss of tagging (logarithmic in time) corresponds to synaptic endocytosis. The Murdock recent item recall probabilities follow a logarithmic decay with time of recall. The slope of the decay increases with increasing presentation rate. This is consistent with endocytosis since higher presentation rates lead to a higher frequency of exocytosis which increases the intracellular concentration of Ca ions which in turn increases the speed of the endocytosis process (Sankaranarayanan and Ryan, 2001). The initial Murdock items, with an effective low presentation rate, decay with the slowest logarithmic slope.\ud If short term memory decays and this decay is hurried by increases in the item presentation rates, a slower presentation rate leads to a slower decaying short term memory. Presentation rate is then presumably an important factor in determining the probability of items entering long term memory. It suggests a basis for memory loss in busy adults, a basis for the importance of slow music practice, a basis for long term memory deficiencies for people with attention deficits who may be artificially increasing the presentation rates of their surroundings

Topics: Cognitive Psychology
Year: 2009
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