Due to the lower stimulus power in Magno stimuli and the reduced amplitude of response in the periphery, participants underwent an additional three runs for the Magno VESPA in the periphery, whenever possible. The average number of Magno VESPA runs in the periphery was 4.48 for TD and 4.41 for ASD. The participants were instructed to maintain fixation on the center of the screen for the duration of each run. To increase the likelihood that participants fixated on the center of the

screen and to decrease boredom, they completed the following tasks. For the centrally presented stimuli, the task was to detect the occurrence of an ‘X’ of mean luminance in the center of the screen. For peripherally presented stimuli, Proteasome activity participants had to detect a subtle luminance buy Osimertinib change in a fixation cross presented in the center of the screen (this cross was

not present for the centrally presented stimuli). The inter-stimulus interval for the targets was set to random values between 6 and 24 s. Seventy-channel scalp EEG was recorded, amplified and digitized at 512 Hz using Biosemi ActiveTwo amplifiers, with a low-pass filter at 103 Hz. The acquisition of the data occurs relative to an active two-electrode reference, which drives the average potential of the participant as close as possible to the analog to digital (AD) conversion reference voltage of the AD box (for a description of the Biosemi active electrode system referencing and grounding conventions, see www.biosemi.com/faq/cms&drl.htm). Eye movements were recorded using an EyeLink 1000 system in head-free mode. In this setting, the eye-tracker corrects for small head movements and remains very accurate even with changing head position. Eye position was recorded

at 500 Hz, synchronized with the EEG recording using triggers every second. Every five blocks, or more frequently if necessary, the eye-tracker was calibrated using a nine-point grid. The recorded EEG data were filtered between 0.8 and 50 Hz using 6th order Chebyshev filters with zero phase-shift. These filters have the advantage of very high attenuation in the stop band with minimal attenuation in the pass-band (< 0.1 dB). Bad Uroporphyrinogen III synthase channels were determined using statistics of neighboring channels and interpolated using linear, distance-weighted interpolation. The EEG data were then referenced to the average. The raw eye-tracking data were filtered using a 4th order Butterworth low-pass filter with 15 Hz cut-off. Due to calibration error, the eye-tracker may represent the participant’s horizontal gaze position up to 1° to the left or right of the intended position. This ‘misrepresentation’ will be consistent for all blocks during a calibration period.