Memory span

In psychology and neuroscience, memory span is the longest list of items that a person can repeat back in correct order immediately after presentation on 50% of all trials. Items may include words, numbers, or letters. The task is known as digit span when numbers are used. Memory span is a common measure of short-term memory. It is also a component of cognitive ability tests such as the WAIS. Backward memory span is a more challenging variation which involves recalling items in reverse order. In psychology and neuroscience, memory span is the longest list of items that a person can repeat back in correct order immediately after presentation on 50% of all trials. Items may include words, numbers, or letters. The task is known as digit span when numbers are used. Memory span is a common measure of short-term memory. It is also a component of cognitive ability tests such as the WAIS. Backward memory span is a more challenging variation which involves recalling items in reverse order. Functionally, memory span is to measure the number of discrete units over which the individual can successively distribute his attention and still organize them into a working unit. To generalize, it refers to the ability of an individual to reproduce immediately, after one presentation, a series of discrete stimuli in their original order. Experiments in memory span have found that the more familiar a person is with the type of subject matter presented to them, the more they will remember it in a novel setting. For example, a person will better remember a sequence in their first-language than their second-language; a person will also remember a sequence of words better than they would a sequence of nonsense syllables. According to a theory by Alan Baddeley and Graham Hitch, working memory is under the influence of three key mechanisms: the visuospatial sketchpad, the central executive, and the phonological loop. A mechanism called the episodic buffer was later added to the model. The phonological loop is the mechanism that facilitates learning and memory by storing information (in the articulatory loop) and refreshing or rehearsing it in our memory (in the acoustic store). The phonological similarity effect is when items in a list have similar features (e.g. similar sound), they are more difficult to remember. Likewise, the more different the items in a list are, the easier it is to recall them. Memory span tasks since the formulation of Baddeley and Hitch's theory have been helpful as support for the phonological loop as part of the working memory. A structural definition of memory span is difficult to give, for one immediately is faced by the distinctions between the prerequisites for memory span, and the actual processes involved. 'Associability” is required in memory span. This term refers to the ability of the subject to group the series of elements together: to perceive relationships among the series in order to better reproduce them.Still another process involved in memory span is that of imagery. The subject, in order to be able to reproduce the series presented, must be able to image the series. The actual reproducing of the series of stimuli involves the process of memory. If the individual possessed no memory at all, reproduction of the series would be impossible. It is also known that memory span and memory are different in the length of time over which reproduction is possible. Memory span is transitory; memory is fairly permanent. In addition, the amount of material involved in memory span is ordinarily much less than the amount of material involved in memory. Reproduction of the series also involves certain other 'reproduction factors,' such as language ability and arithmetical proficiency. A digit-span task is used to measure working memory's number storage capacity. Participants see or hear a sequence of numerical digits and are tasked to recall the sequence correctly, with increasingly longer sequences being tested in each trial. The participant's span is the longest number of sequential digits that can accurately be remembered. Digit-span tasks can be given forwards or backwards, meaning that once the sequence is presented, the participant is asked to either recall the sequence in normal or reverse order. Digit-span tasks are the most commonly used test for memory span, partially because performance on a digit-span task cannot be affected by factors such as semantics, frequency of appearance in daily life, complexity, etc. Verbal working memory is involved in many everyday tasks, such as remembering a friend's telephone number while entering it into a phone and understanding long and difficult sentences. Verbal working memory is also thought to be one of the elements underlying intelligence (often referred to as 'IQ,' meaning 'intelligence quotient'); thus, the digit span task is a common component of many IQ tests, including the widely used Wechsler Adult Intelligence Scale (WAIS). Performance on the digit span task is also closely linked to language learning abilities; improving verbal memory capacities may therefore aid mastery of a new language. There are a number of factors which affect memory span. Some of the factors are extrinsic, or present in the testing situation itself. These factors, if not carefully controlled, cause the memory span test to be statistically unreliable. While the existence of many of these factors have been recognized, extensive studies on their importance have yet to be done. Some of these extrinsic factors include stimulus grouping, response grouping, presentation rate, and S-R compatibility. Other factors are intrinsic in the individual, and it is these factors which are the basis of 'true' memory span. Though numerous factors affect memory span, the test is one that shows surprisingly high reliability. Results obtained by different investigators show that the reliability coefficients for memory span are quite high.