Working memory for sequences of verbal stimuli: The impact of stimulus type and presentation mode

Previous studies have shown that the use of a static or dynamic mode of presenting a non-verbal series (a sequence of strokes that make up a broken line, like an open polygonal chain), as well as varying the retention time of this information in working memory, can affect the accuracy and temporal characteristics of the sequence reproduction. The present study aims to investigate the effects of the presentation mode and the retention time on the memorization and reproduction of a sequence of verbal items. For this purpose, adult subjects were asked to memorize and reproduce sequences of letters and digits which were visually presented either simultaneously (statically) or sequentially (dynamically). The response delay time (500 or 3000 ms) and the length of the sequences (from 3 to 5 elements) were varied. As dependent variables, the accuracy of stimulus reproduction and the reaction time were computed. It turned out that the memorization of verbal sequences depended on the presentation mode (static or dynamic), and the static mode seemed to lead to a more complete representation of the memorized sequences. It was shown that the sequences of letters and digits are memorized differently. It is assumed that, unlike sequences of letters, sequences of digits are stored in working memory not as a sequence of individual elements but as shorter sequences of larger chunks or even as a whole. In contrast to the situation of reproducing a broken line, in the case of reproducing verbal sequences, no significant change in the reaction time was revealed when the time of information retention in working memory was varied