There are a number of implications from this work for existing EEG studies in those with ASD. Consistent with previous reports, these data provide no evidence for difference in P1 amplitude in participants with ASD. Although there is one report of reduced P1 amplitude in children/adolescents with pervasive developmental disorder, including ASD (Hoeksma et al., 2004), this may have been due to latency jitter, as ERP amplitude (when calculated from the peak of the averaged single-trials) is intrinsically related to latency variability. Conversely, the suggestion that individuals with ASD may have hyper-responsive visual cortices would predict increased P1 amplitude in those with ASD, and increased latency jitter may mask this potential outcome. However, the data did not support this prediction, as when P1 amplitude was calculated as the median of the single-trial peaks, there was still no group difference in P1 amplitude. The data reported here indicate that establishing degree of latency jitter within each participant is possible, and should be an essential part of ERP analysis if conclusions are to be drawn to regarding the origin of observed group
