| Popis: |
Serial order information is critical in our daily life, as in recalling a phone number, producing a sequence of phonemes when saying a word out loud, or writing down a sequence of letters when spelling. In the current study, we use a multiple case study approach to investigate the extent to which a common serial order system is shared in these daily activities. Three individuals with brain damage due to stroke completed a series of working memory (WM) tasks in both verbal and nonverbal (visuospatial) domains to assess whether they had a WM impairment specific to the capacity to maintain serial order. In addition, participants were administered a series of spoken production and spelling tasks, and the error corpus produced by these three individuals was analyzed to assess whether there was a tendency to produce the correct phonemes/letters in the wrong order. M.B. showed a serial order impairment with verbal but not visuospatial stimuli in WM tasks, whereas the other two participants did not exhibit any serial order impairment in either domain. This dissociation between verbal and nonverbal serial order WM systems provides clear evidence for the domain-specific nature of serial order WM. In both spoken and written production tasks, M.B. had a tendency to make errors that involved producing serial order errors, or errors in which the right segments were produced in the wrong order, whereas the other two participants did not produce serial order errors at rates different than would be expected by chance. The association between M.B.’s serial order impairments in verbal WM, spoken production, and spelling, along with the other two patients’ preserved serial order performance, supports a shared system for processing serial order information in verbal WM and language production. |
