Abstract
Previous visual working memory (VWM) research suggests that encoding and processing of ensembles is similar to processing of individual objects, and has similar attentional and WM limitations, even though capacity estimates for objects are usually established at 4-5 items, and for ensembles – at 2 structural units. However, available findings do not allow direct comparison of the mechanisms and limitations of object and ensemble encoding, as experimental paradigms used for assessment of VWM for objects and ensembles are distinctly different. We systematically examined VWM capacity and precision for objects and ensembles using two methods, change detection (CD) and continuous report (CR). Participants were briefly presented with sets of 1 to 5 objects or spatially intermixed ensembles of different colors (Experiments 1-3), or ensembles of different colors and shapes (Experiment 4), and tasked to memorize them. During CD task they were asked to identify whether two sequentially presented sets were identical, or the color of one element has changed. During CR task they had to adjust the color of the follow-up probe to match the item previously presented at the same location. In Experiment 1 objects and ensembles were distributed randomly. In Experiment 2 objects were presented at the same distance from the fixation point. In Experiment 3 objects were scaled up to have the same area as ensembles, to control for total retinal stimulation area. Experiment 4 included two CR tasks; in one of the conditions ensembles had another unique feature (shape, irrelevant to the task). We found that VWM estimates for objects and ensembles do not differ significantly within the same set size conditions, nor between the experiments, which is in line with the notion that ensemble representations boost memory capacity for objects, and indicates that there is no decrease in precision when memorizing ensembles, as compared to objects.
Meeting abstract presented at VSS 2016