Summary: How Many Locations Can Be Selected at Once?
Steven L. Franconeri
George A. Alvarez
Massachusetts Institute of Technology
James T. Enns
University of British Columbia
The visual system uses several tools to select only the most relevant visual information for further
processing, including selection by location. In the present study, the authors explored how many locations
can be selected at once. Although past evidence from several visual tasks suggests that the visual system
can operate on a fixed number of 4 objects or locations at once, the authors found that this capacity varies
widely in response to the precision of selection required by the task. When the authors required precise
selection regions, only 23 locations could be selected. But when the selection regions could be coarser,
up to 67 locations could be selected. The authors discuss potential mechanisms underlying the selection
of multiple locations and review the evidence for fixed limits in visual attention.
Keywords: visual attention, selection, capacity, span, location
At any moment in time, the visual world presents a vast array of
visual information to the eyes. The visual system has several tools
available to help it select the information that is most relevant to
current goals and behavior. One such tool is selection by features.