Measuring Verbal Working Memory Span
Source: Laboratory of Jonathan Flombaum—Johns Hopkins University
Why is it relatively hard to remember everything on a shopping list if it includes more than just a handful of items? Why is it possible to remember a phone number that one just heard, but not two or three phone numbers at once? Why is it difficult to remember names when several new people are introduced at the same time?
The answer has to do with the fact that over short-durations people rely on a specialized memory system called working memory. Unlike long-term memory, working memory has a very limited capacity. It is there so that information can be kept in mind, studied, manipulated, and then transferred to other memory and cognitive systems. But in order to serve in this active role, it needs to be selective, admitting only limited amounts of information at a time.
Experimental psychologists tend to think that people possess independent working memory systems for different kinds of information, with a major division between verbal and visual information. Each of these systems has an independent capacity limit.
To measure a person’s verbal working memory capacity limit—often called, his or her memory span—experimental psychologists often use a verbal list paradigm.
This video will demonstrate the measurement of verbal working memory span using a verbal list paradigm.
1. Make a set of word lists.
- To make stimuli for this experiment, gather 40 index cards and a pen.
- Generate a random list of 210 common nouns, words like, car, dog, pen, boat, chair, and hammer.
- Each index card will include three, four, five, six, seven, eight, or nine common nouns on it. Make five cards with each number. Don’t repeat nouns from list to list, and try not to have them group together by category. For example, avoid lists with only animals or tools or foods. Instead, tr
In terms of verbal memory span, one way to classify a person’s ability is as the longest list for which he/she performs better than 75% correct for all word positions. For this participant, that seems to be a list with five words (Figure 1), which makes the verbal working memory span five.
Figure 1. List learning accuracy as a function of word position a
Measures of verbal working memory, including list learning, are used in a variety of contexts as a quickly and easily obtainable measure of an individual’s cognitive ability. This is because memory span is known to correlate very reliably with IQ. In fact, memory span is a sub-test on many IQ tests. In clinical settings, verbal span can thus be used to determine whether illness or brain damage has had an effect on cognitive functioning in general, and as indicator of degenerative diseases such as Alzheimer’s.
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