<Li> On the other hand, patients with dysarthria, whose speech problems are secondary, show a normal capacity for rehearsal . This suggests that it is the subvocal rehearsing that is crucial . </Li> <P> An accumulation of literature across decades has lent strong support to the theory of phonological STS . In a 1971 study, Stephen Madigan demonstrated that a larger recency effect is seen during forward serial recall when people are presented a list auditorally as opposed to visually . (A smaller effect is seen in backwards serial recall .) In his study, auditory presentation led to greater recall of the most recently studied items . Catherine Penney expanded on this discovery to observe that modality effects can also be found in the case of free recall tasks . In 1965, Dallett had discovered that this observed modality effect is greatly reduced by the addition of a "suffix" item to the presented list; this suffix is a distractor item that is not to be recalled . Robert Greene utilized this observation in 1987 to discover that this suffix effect has a larger impact on lists learned auditorally as opposed to visually . The culmination of all of these findings results in strong support of the theory that there is a short - term store that phonologically stores recently learned items . In addition, Bloom and Watkins found that the suffix effect is greatly diminished when the suffix is not interpreted as linguistic sound, which agrees with the phonological short term store theory as it would be largely unaffected by non-linguistic distractors . </P> <P> Alan Baddeley's theory of working memory has yet another aspect to which memory can be stored short term . The visuo - spatial sketchpad is this store that holds visual information for manipulation . The visuo - spatial sketchpad is thought to be its own storage of working memory in that it does not interfere with the short term processes of the phonological loop . In research, it has been found that the visuo - spatial sketchpad can work simultaneously with the phonological loop to process both auditory and visual stimuli without either of the processes affecting the efficacy of the other . Baddeley re-defined the theory of short - term memory as a working memory to explain this phenomenon . In the original theory of short - term memory, it is understood that a person only has one store of immediate information processing which could only hold a total of 7 items plus or minus two items to be stored in a very short period of time, sometimes a matter of seconds . The digit - span test is a perfect example of a measurement for classically defined short - term memory . Essentially, if one is not able to encode the 7 plus or minus two items within a few minutes by finding an existing association for the information to be transferred into long - term memory, then the information is lost and never encoded . </P> <P> However, visuo - spatial short - term memory can retain visual and / or spatial information over brief periods of time . When this memory is in use, individuals are able to momentarily create and revisit a mental image that can be manipulated in complex or difficult tasks of spatial orientation. There are some who have disparities in the areas of the brain that allow for this to happen from different types of brain damage . There can also be a misunderstanding here in the differences between transient memories such as the visual sensory memory . A transient memory is merely a fleeting type of sensory memory . Therefore, as the visual sensory memory is a type or sensory memory, there is a store for the information, but the store last for only a second or so . A common effect of the visual sensory memory is that individuals may remember seeing things that weren't really there or not remembering particular things that were in their line of sight . The memory is only momentary, and if it isn't attended to within a matter of seconds, it is gone . </P>

What are the 4 main components of baddeley’s wm model (as of 2000 or later)