Objectives: The current study investigated whether there are differential patterns in verbal working memory (WM) tasks between a normal control group and individuals with mild cognitive impairment (MCI) depending on the manipulation of processing load. Methods: Sixteen individuals with MCI and 16 normal controls participated in the study. The verbal WM tasks consisted of the two types (semantic vs. phonological). The processing load consisted of two types of manipulations (time-interval vs. interference). In the semantic WM task, participants read the target word and judged, after a certain inter-stimuli interval (ISI), whether following words belong to the same category or not. For the phonological WM condition, participants judged whether the following words rhymed with the target words in a final syllable. Results: Results from time-related processing load (ISI 1s vs. ISI 5s) revealed that the MCI group showed significantly lower accuracy and longer response time on the WM tasks than the normal group. A significant two-way interaction between the group and WM task types suggested that the MCI group presented significantly longer response time in the semantic WM task than the phonological WM task compared to the normal group. Results from interference-related processing load (interference vs. no interference) revealed that the MCI group showed significantly lower accuracy and longer response time than the normal group. Conclusion: The results suggested that the manipulation of the processing load condition showed greater effects on WM task for the MCI group both in accuracy and response time. The study indicates that the type of cognitive processing load may differentially affect different domains of WM.
- Cognitive processing load
- Mild Cognitive Impairment (MCI)
- Verbal working memory
- Working memory tasks