*2.1. Participants*

Eighteen students (9 male) of the University of Lübeck participated. This sample size was well in the range of our previous studies using this task where consistent behavioral and ERP effects had been obtained. Informed written consent was obtained and 7 € per hour were paid. All participants reported normal or corrected-to-normal vision, normal color vision, and no history of neurological disorders. Four of those 18 participants turned out to be unable to identify T2 reliably above chance, with mean identification rates markedly below 20%, and were excluded from analysis. The remaining 14 participants (7 males) were aged 20 to 29 years (M = 25, SD = 2.7). One was left-handed (laterality score −100), the others were right-handed, with a mean score of +94 (SD 9) in the Edinburgh Handedness Inventory [27].

#### *2.2. Stimuli and Apparatus*

The task is illustrated in Figure 1. Two simultaneous sequences of black capital letters of the Latin alphabet were rapidly (9/s) presented left and right from fixation. The 17" screen had a white background (120 cd/m2) and was driven with 100 Hz at about 1.2 m from participants' faces. Letters were 8.5 mm wide and 11 mm high (0.5◦ × 0.6◦ visual angle) with their inner edges 10 mm from fixation (0.6◦). Fixation was marked by a small red cross (0.1◦ × 0.1◦) at screen center. In each trial, two targets had to be identified. The first target (T1) was a red letter (24 cd/m2; D, F, G, J, K, or L). The second target (T2) was a blue digit (18 cd/m2; 1, 2, 3, 4, 5, 6, 7, 8, or 9). Background stimuli consisted of all other letters in black (standard), or in blue (color lures) or of the digits 1–9 in black (digit lures). Presentation® software, version 14.5, was used for experimental control (Neurobehavioral Systems Inc., Berkeley, CA, USA).
