Three key issues with respect to decision aiding interface design were investigated within a tactical situation assessment paradigm: aiding type (situation assessment vs. response), display formats (verbal vs. spatial), and performance under stress (4-second vs. 8-second presentation). It was hypothesized that aiding would improve performance, particularly under conditions of time stress. Further, it was hypothesized that the spatial format would be more compatible with the cognitive demands of the spatially-demanding situation assessment paradigm, and therefore performance would benefit more from these formats. Results indicated a strong detrimental effect of time stress (lower optimality and confidence ratings). No difference was found between the two types of aiding (situation assessment vs. response). However, a clear advantage for the spatial format was observed. Responses for the spatial formats were faster and confidence ratings were higher, particularly in the situation assessment condition. Under high time stress, spatial aiding improved performance over both the verbal aiding and unaided formats. In fact, spatial aiding under time stress improved performance to equal that of the low-stress condition. Collectively, these results provide support for display format/task processing compatibility, particularly where task performance is time-limited.