Working memory for movements, positions and colors - behavioral studies

A number of behavioral and neurocognitive studies have shown that visuo-spatial and visual-object information in working memory can be dissociated. However, as reflected in the variety of operationalizations, there is no consensus on the definition and delineation of these two types of information. In particular, the role of dynamic aspects in spatial information is not clear. We hypothesize that static-spatial information (i.e. absolute position), dynamic-spatial information (i.e. movement), and visual-object features (e.g. color) are separable features and can be retained selectively in working memory. We conducted three behavioral studies within the framework of an S1-cue-S2-paradigm. Participants were presented with a first stimulus and were required to compare it to a second stimulus that was presented a few seconds later. In order to enable selective rehearsal, in a part of the trials we presented a cue after S1-offset indicating the specific to-be-evaluated feature. In the unspecific condition the cue specified two features. We expected that specific cues lead to better memory performance than unspecific cues because the former but not the latter allow selective rehearsal. Stimuli were either two moving colored dots or a static layout of four colored dots. Participants' performances were higher in the specific than in the unspecific condition. We take this as evidence that selective rehearsal of movement, position, and color information is possible and that these features are separable in visual working memory. In two further experiments we modified the perceptual stimulus qualities in order to equate difficulty across tasks and to make the tasks suitable for a planned fMRI study.