function [Amp, Latency] = ave_peak(Datastack,sign,t1,t2,pre);
% averages over all locations. finds positive or negative peak of this
% average timecourse for each epoch.
% if sign is 1, find the positive peak. if sign is -1, finds negative peak.
MeanData = mean(Datastack);
MeanData = permute(MeanData,[2,3,1]);
MeanData = sign*MeanData;
[Amp, Latency] = peak(MeanData,t1,t2,pre);
end