Figure 1.

Pictorial experimental design. The trial structure (shown at left) was the same across both conditions. Subjects first saw a critical shape (either a colored picture or an outline on a colored background) and were asked to judge if a following test shape matched the initial stimulus. On Outline trials (A), only the shape was required to match. On Colored Shape trials (B), both the color and shape were required to match. Only activity evoked during the viewing of the critical stimuli was subject to analysis. Subjects saw an equal number of matching and non-matching trials in both conditions.