Retention of Verbal and Nonverbal Serial Information in Working Memory

This article presents the results of an experimental study of retention in working memory (WM) and subsequent motor reproduction of two types of serial information, verbal ( sequence of letters) and non-verbal (broken lines). Series of elements were presented in two modes: statically (all elements are shown simultaneously) and dynamically (the sequence is shown element by element). We investigated the influence of the sequence presentation mode, the sequence complexity (number of its elements) and WM delay period on the accuracy and the latent time (reaction time) of reproduction of the memorized series of elements. The study involved 33 adult right-handed subjects. The following results were obtained. It turned out that the accuracy of reproduction of both types of sequences in a qualitatively similar way depends on the presentation mode and the number of elements: the reproduction is less accurate in the dynamic mode as compared to the static mode, and the accuracy decreases with increasing sequence length in both modes. The use of the dynamic presentation mode has a greater effect on the accuracy of reproduction of broken lines than letter sequences. In contrast, increasing the number of elements reduces the accuracy of letter sequences reproduction more than the accuracy of broken lines reproduction. It was revealed that WM delay period significantly affected the latent time of the motor response only when broken lines but not letter sequences were reproduced. The latent response time increases with an increase in the length of the sequence of letters but does not change with an increase in the number of segments of the broken line. These results points to some differences in the mechanisms of encoding and storage of the verbal and nonverbal serial information in working memory. It seems that verbal information, when compared to non-verbal information, is represented internally to a greater extent as a sequence of elements and, at the same time, undergoes less changes during retention in working memory in the tasks where reproduction of the order of elements is required.