Error rates were analyzed using the same design as for RTs. There were significant main effects of distractors, F(1, 22) = 13.4, p < 0.005; target presence, F(1, 22) = 25.3, p < 0.001; display size, F(3, 66) = 4.6, p < 0.01; and task, F(1, 22) = 55.6, p < 0.001. These indicate greater error rates with conjunction than with nonconjunction distractors (3.1% vs. 1.9%), on target-present than on target-absent trials (3.4% vs. 1.6%), and in the experimental task than in the control task (2.8% vs. 2.2%), as well as increasing error rates as a function of display size, except for a dip with five-item displays (2.4%, 1.8%, 2.7%, and 2.9% with display sizes of 3, 5, 7, and 9, respectively). The two-way Target presence × Task interaction was significant, F(1, 22) = 5.0, p < 0.001, indicating that the effect of target presence was greater in the experimental than in the control task (effect size of 2.5% vs. 1.0%). The significant Display size × Task interaction, F(3, 66) = 3.7, p < 0.05, shows that the pattern of error rates as a function of display size varied according to task (roughly, increasing with display size for the experimental task and trending irregularly downward with increasing display size for the control task). There were significant two-way interactions of Distractors × Display size, F(3, 66) = 3.5, p < 0.05, and Target presence × Display size, F(3, 66) = 11.3, p < 0.001, but they were qualified by the three-way Distractors × Target presence × Display size interaction, F(3, 66) = 3.2, p < 0.05.