How Does The Brain Work?
For years, researchers delineated memory into two types: short term and long term. More recently, after the advent of LaBerge and Samuels Automaticity Theory (1974) and Perfetti's Verbal Efficiency Theory (1988), this construct was re-imagined as working memory--which adds the dimension of processing to the function of storage (Daneman & Carpenter, 1980). As they explain, "Working memory is assumed to have processing as well as storage functions; it serves as the site for executing processes and for storing the products of these processes" (p. 450). Working memory is active rather than passive.
Tanabe, Azumi, Osaka, & Naoyuki (2009) explain that working memory consists of at least two domains, the verbal domain and the visuospatial. They note that there is not a sufficient test for visuospatial working memory, and set out to create one, entitled the Picture Span Test. They explain that these two aspects of working memory perform different functions. It is the visuospatial aspect of working memory that allows for "reading comprehension, reasoning, language learning, and so on" (p. 1). Because working memory involves processing information, the authors argue that other tests of short term memory have been insufficient (such as the digit span test and the word span test), as noted also by Daneman and Carpenter (1980): Perhaps "digit span and word span tests do not sufficiently tax the processing component of working memory," which would explain why there was little correlation between these measures and reading comprehension (p. 451). These tests simply required the memorization of words or numbers, but no processing, no comprehension, occurred. With the conceptualization of working memory, a more complex test was needed, a test that required the processing of information. The Picture Span Test satisfies that requirement.
Adams (1990) would argue that working memory is comprised of different domains but that they interact with one another. These domains loop, each informing the other and allowing the reader to encode propositions more efficiently. The verbal domain and the visuospatial domain are interconnected, especially when one performs the difficult task of reading. Subvocalization is a rehearsal method of storing the words in working memory as the next word is read and phrases and propositions are encoded or translated into meaning. Of course, these loops occur simultaneously and with little effort as a reader becomes more advanced. The orthographic processor would be situated in the visuospatial domain of working memory, and the phonological domain would be in the verbal domain of working memory. Where then would the meaning and context processors reside?
I argue that these processors are in both areas of working memory. Depending on the stimuli, the context and memory processors operate in either area of working memory. Take, for example, listening. If a person is to comprehend something they hear, these processors are activated verbally. If they comprehend something they read, these processors are activated visually. It depends on the input. This theory explains why a student's listening comprehension can be much higher than reading comprehension if the student has a reading disability rather than a cognitive one.
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