remove baseline correction

Author: GRousselet

mi50it.m

@@ -0,0 +1,67 @@
+function it = mi50it(data,xf,pts,plotit)
+% it = mi50it(data,xf,pts,plotit)
+%
+% Computes the 50% integration time of mutual information data.
+% 50it is a measure of processing speed that alleviates the need to consider peaks,
+% by considering the shape of a time-course in a time-window of interest.
+% The measure was introduced in this paper:
+% Rousselet, G.A., Gaspar, C.M., Pernet, C.R., Husk, J.S., Bennett, P.J. & Sekuler, A.B. (2010)
+% Healthy aging delays scalp EEG sensitivity to noise in a face discrimination task.
+% Front Psychol, 1, 19.
+% http://www.frontiersin.org/perception_science/10.3389/fpsyg.2010.00019/abstract
+% The current version is slightly different, starting with a baseline correction
+% so as to not integrate MI values around baseline level.
+%
+% data      = a column vector or time x participant matrix of positive only observations, e.g. mutual information
+% xf        = time vector - default -300:2:600
+% pts       = points at which to estimate the time-course - default [0 500]
+% plotit    = 1 to get a figure, 0 otherwise
+
+% Copyright (C) 2016 Guillaume Rousselet - University of Glasgow
+
+if nargin < 2
+    xf = -300:2:600;
+end
+if nargin < 3
+    pts = [0 500];
+end
+if nargin < 4
+    plotit = 0;
+end
+
+[nf,np] = size(data);
+frame_selec = xf>=pts(1) & xf<=pts(2);
+xf50it = xf(frame_selec);
+nf50it = numel(xf50it);
+
+% baseline correction
+% data = data - repmat( median(data(xf<0,:),1), [nf 1] );
+
+% cumulative sum
+data = data(frame_selec,:);
+data = cumsum( data, 1 );
+
+% normalization
+data = data - repmat(min(data,[],1), [nf50it 1]); % figure;plot(Xf0500,cs1)
+data = data ./ repmat(max(data,[],1), [nf50it 1]); % figure;plot(Xf0500,cs1)
+it = zeros(np,1);
+for P = 1:np % for every participant
+    it(P) = interp1(data(:,P),xf50it,.5,'linear');
+end
+
+if plotit == 1
+    
+    cc = parula(np);
+    figure('Color','w','NumberTitle','off','Name','50% integration time')
+    hold on
+    for P=1:np
+        plot(xf50it,data(:,P),'Color',cc(P,:),'LineWidth',2)
+        plot([it(P) it(P)],[0 1],'Color',cc(P,:),'LineWidth',1)
+    end
+    set(gca,'LineWidth',2,'YLim',[0 1],'XLim',pts,'XTick',pts(1):50:pts(2))
+    set(gca,'FontSize',14,'Layer','Top')
+    xlabel('Time in ms','FontSize',16')
+    ylabel('Normalised MI','FontSize',16')
+    box on
+    
+end