diff --git a/tt.m b/tt.m
index e6ee1207eace460346c414d164627de2541d8fbc..b7a8b40d2439f78b14e9c34fce537acfde879a23 100644
--- a/tt.m
+++ b/tt.m
@@ -27,6 +27,9 @@ function [a_out, b_out, c_out]=tt(x)
 % $Revision$
 %
 % $Log$
+% Revision 3.8  2013/08/22 06:35:01  marwan
+% bugfix in estimation black and white vertical lines
+%
 % Revision 3.7  2010/06/30 12:02:52  marwan
 % Help text modified
 %
@@ -123,7 +126,7 @@ try
 
         if nargout==3
            c_out=zeros(length(tw),1);
-           c_out=tw;
+           c_out=tw+1; % +1 correction to get the correct RT
         end
 
         if nargout>=2