Abstract
Visual working memory relies heavily on the active maintenance of representations. However, it is unclear whether this active maintenance can co-occur with other concurrent processing of stimuli. Sparked by this question, we used event related potentials (ERPs) - specifically contralateral delay activity (CDA) - to create a continuous marker of active maintenance of lateralized stimuli during the processing of lexical stimuli. Participants were asked to remember four colored items presented on the right or left side of the screen for a change detection task. A lexical item (word or consonant string) was presented during the 1500 ms retention interval on a subset of trials. Participants were instructed to either ignore these items and focus entirely on the memory task (single-task condition), or to indicate whether the item presented was a word or consonant string (dual-task condition). A CDA to the lateralized memory items was observed for both conditions prior to, or in the absence of, an intervening stimulus. However, the CDA was disrupted by the processing of the lexical items during the duals task condition, but not the single task condition. A larger N400 - a component associated with semantic and orthographic processing - was found for words compared to consonant strings in both conditions, indicating that participants differentiated between words and consonant strings in both conditions. Thus, during the single-task condition, the CDA was not disrupted by the lexical stimuli even though the N400 data indicate that these stimuli were discriminated. Taken together, these finding suggest that active maintenance is unimpeded by automatic lexical processing but fails when this same processing must be tied to a non-automated task. Interestingly, behavioral measures show only a minor decrease in change-detection performance in the dual-task condition, providing evidence of a secondary working memory process that can support the memory task when the CDA has been disrupted.
Meeting abstract presented at VSS 2017