Average (±standard error of the mean) DT (A) and RT (B) of 18 smokers performing the SDT, the angle discrimination (Sel-A), color discrimination (Sel-C), or combined angle and color discrimination task (divided attention, DIV) while wearing a nicotine or placebo patch. Significant differences between the nicotine and placebo session (**P < 0.01, ***P < 0.001, paired t-test) and between task conditions (###P < 0.001, paired t-test) are indicated.