To obtain baseline EEG at both the 5- and 10-month visits, infants sat on their mothers’ laps and watched a research assistant manipulate a toy containing brightly colored balls on a testing table 1.1 meters in front of them. This baseline procedure quiets the infant, yields minimal eye and gross motor movements, and allows the infant to tolerate the EEG cap (e.g. Bell, 2001, 2012). Recordings were made from 16 left and right scalp sites: frontal pole (Fp1/Fp2), medial frontal (F3/F4), lateral frontal (F7/F8), central (C3/C4), temporal (T7/T8), lateral parietal (P7/P8), medial parietal (P3/P4), and occipital (O1/O2). All electrode sites were referenced to Cz during recording. The electrical activity from each lead was amplified using separate James Long Company Bioamps (Caroga Lake, NY). During data collection, the high pass filter was a single pole RC filter with a 0.1 Hz cut-off (3 dB or half-power point) and 6 dB per octave roll-off. The low pass filter was a two-pole Butterworth type with a 100 Hz cut-off (3 dB or half-power point) and 12 dB octave roll-off. Activity for each lead
