ERP data were collected over the course of more than 20 years using two different systems. For older- and younger-cohort MTFS participants1 (74% of the sample), electroencephalogram (EEG) was recorded via Grass Neurodata 12 systems (256-Hz sampling rate, pass-band from .01 to 30 Hz with a roll-off of 6 dB). For each trial, 2 s of EEG, including a 500-ms prestimulus baseline, were written to disk. Hardware constraints limited the number of signals recorded to three: one from midline parietal scalp and two from left and right parietal cortex, respectively. Signals were referred to linked ear electrodes. Eye blinks and other eye movements were recorded by means of a transverse electrode arrangement, with one superior to the eye and one next to the outer canthus. For MTFS enrichment sample (ES) participants, a BioSemi ActiveTwo system was used to collect continuously recorded EEG data with a sampling rate of 1024 Hz. Stimulus delivery was controlled by a script written in E-Prime software 1.1 (Psychology Software Tools, Pittsburgh, PA) to mimic the original program and pass event triggers to the recording system.
