Work Memories Reflecting Change Detection
Anka Slana Ozimic
Progress in Machines and Systems, Vol. 8, No. 1, 2019.
DOI: 
Link: http://www.dline.info/pms/fulltext/v8n1/pmsv8n1_2.pdf
Abstract:
The capacity of working memory to maintain visual information is highly limited and varies significantly across
individuals. An important research effort is to understand the mechanisms of its limitation, one being the efficient selection of
the relevant items from the immediate external environment to encode and maintain in working memory stores, while preventing
the irrelevant items to occupy itâ€™s capacity. Recently, a series of EEG studies using lateralized change detection task, in which
the participants only have to maintain items presented on one visual hemifield, while irrelevant items are also presented on
the opposite hemifield, identified a neurophysiological correlate of storage capacity in the form of contralateral delay
activity (CDA) wave. Moreover, studies revealed that low-capacity participants maintain irrelevant items along the target
items, when both are presented in the same visual hemifield, indicating a reduced ability to filter irrelevant stimuli from visual
working memory. These studies, however, do not consider the possibility that participants might also maintain the irrelevant
items presented to the opposite visual hemifield. To address this concern, we designed an experiment in which we directly
manipulated the presence of distractors in the irrelevant visual hemifield to estimate and control for their effect. Twenty-eight
participants took part in a visual working memory experiment in which they were asked to maintain orientation of items
presented to the left or right visual hemifield, while the distracting items were either present or absent in the opposite visual
hemifield. The results revealed significantly lower estimates of the capacity in the presence vs. absence of distractors,
suggesting that participants were not able to ignore the distracting items presented to the opposite visual hemifield, challenging
the validity of the estimates of visual working memory capacity in CDA and other studies employing lateralized change
detection task.