Herbal Extracts That Reduce Ocular Oxidative Stress May Enhance Attentive Performance in Humans

Figure 3

Procedure for cluster-based permutation test in ERP (spatiotemporal data) analysis. First, -tests were conducted for each channel and time point for all subjects. Then, we obtained an uncorrected spatiotemporal -value map. Second, we clustered the selected samples in connected sets based on spatiotemporal adjacency. Positive or negative -values in a cluster were summed separately. Third, we permuted the ERP without condition; the condition was the circle, star, or bat image. After the permutation, we performed -tests for each channel and time point. Fourth, we iterated the third procedure 1000 times to obtain 1000 -value maps. Fifth, we determined the largest of the cluster-level statistics for each of the 1000 -value maps. Sixth, we constructed a histogram of the largest values and a probability density function based on the cluster-level statistics. Finally, we obtained a value that was approximated and corrected by this nonparametric permutation test from the probability density function. Reprinted from [18]. Copyright 2016 by the Neurosignals.