Abstract
Electrophysiological studies have demonstrated that the maintenance of items in visual working memory is indexed by the contralateral delay activity (CDA). The CDA is modulated by the set size of the memory array, with larger CDA amplitudes as set size increases, plateauing at visual working memory capacity. Investigations of the CDA have primarily utilized simple visual items, such as colored squares, or picture stimuli. Despite the frequent use of letter stimuli in seminal investigations of visual attention and memory, it is unknown whether visual working memory for letters also elicits a typical load-sensitive CDA. Given their close associations with language and phonological codes, it is possible that participants store letter stimuli phonologically, and not visually. The purpose of this study was to use the CDA to determine whether letter stimuli tend to be stored visually or verbally in a change-detection task. Participants completed a standard visual change-detection task while their electroencephalography (EEG) was recorded. Stimuli comprised either colored squares or uppercase consonants. Behavioral accuracy of change detection decreased with increasing set size for both colored squares and letter stimuli. The ERPs showed that a CDA was present for both colored squares and letter memory arrays, as were the capacity limited set-size effects for both types of stimuli, suggesting that letters did not appear to be phonologically recoded. These results suggest that, despite their verbal associations, letters also elicit the electrophysiological marker of visual working memory encoding and storage.
Meeting abstract presented at VSS 2018