Figure 2. Experimental design.

(a) Counterbalancing of object category to task relevance across participants. The assignment of the three object categories to their levels of behavioral relevance was counterbalanced across participants, creating three different participant groups. For group 1 (black), people and cars were the target and distracter categories and trees were the neutral category. For group 2 (light grey) cars and trees were assigned to be the target and distracter categories while people constituted the neutral category. For group 3 (dark grey), people and trees were the target and distracter categories while cars constituted the neutral category. (b) Trial structure. Participants indicated on each trial with a button press whether or not the target category was present in the photograph.