Although maintaining situation awareness (SA) is a critical skill for many complex tasks, there have thus far beenfew rigorous computational approaches to modeling SA behavior and performance. We developed a preliminary computationalmodel of SA focused on remembering the locations of static objects in the visual field. We built this model on the foundationof the ACT-R cognitive architecture, using its declarative memory and vision modules to specify the process of scanning thefield and remembering object locations. In the current work, we demonstrate how this model accounts for human behavior andperformance in two recent experiments: one, a study of object location memory with identities similar to air-traffic control callsigns; and another, a study of remembering the location of shapes of varying size, color, and pattern.