diff --git a/bin/synchronize-private.sh b/bin/synchronize-private.sh
index 11bdfbf62..877bc2d18 100755
--- a/bin/synchronize-private.sh
+++ b/bin/synchronize-private.sh
@@ -1213,6 +1213,7 @@ sync ${ARRAY[*]}
 # istrue.m
 
 ARRAY=()
+ARRAY+=(connectivity/private/istrue.m)
 ARRAY+=(engine/private/istrue.m)
 ARRAY+=(fileio/private/istrue.m)
 ARRAY+=(forward/private/istrue.m)
@@ -1220,6 +1221,8 @@ ARRAY+=(peer/private/istrue.m)
 ARRAY+=(plotting/private/istrue.m)
 ARRAY+=(preproc/private/istrue.m)
 ARRAY+=(qsub/private/istrue.m)
+ARRAY+=(specest/private/istrue.m)
+ARRAY+=(statfun/private/istrue.m)
 ARRAY+=(utilities/istrue.m)
 sync ${ARRAY[*]}
 
diff --git a/connectivity/private/istrue.m b/connectivity/private/istrue.m
new file mode 100644
index 000000000..8148923f3
--- /dev/null
+++ b/connectivity/private/istrue.m
@@ -0,0 +1,42 @@
+function y = istrue(x)
+
+% ISTRUE ensures that a true/false input argument like "yes", "true"
+% or "on" is converted into a boolean
+
+% Copyright (C) 2009-2012, Robert Oostenveld
+%
+% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org
+% for the documentation and details.
+%
+%    FieldTrip is free software: you can redistribute it and/or modify
+%    it under the terms of the GNU General Public License as published by
+%    the Free Software Foundation, either version 3 of the License, or
+%    (at your option) any later version.
+%
+%    FieldTrip is distributed in the hope that it will be useful,
+%    but WITHOUT ANY WARRANTY; without even the implied warranty of
+%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+%    GNU General Public License for more details.
+%
+%    You should have received a copy of the GNU General Public License
+%    along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.
+%
+% $Id$
+
+true_list  = {'yes' 'true' 'on' 'y' };
+false_list = {'no' 'false' 'off' 'n' 'none'};
+
+if ischar(x)
+  % convert string to boolean value
+  if any(strcmpi(x, true_list))
+    y = true;
+  elseif any(strcmpi(x, false_list))
+    y = false;
+  else
+    ft_error('cannot determine whether "%s" should be interpreted as true or false', x);
+  end
+else
+  % convert numerical value to boolean
+  y = logical(x);
+end
+
diff --git a/specest/private/istrue.m b/specest/private/istrue.m
new file mode 100644
index 000000000..8148923f3
--- /dev/null
+++ b/specest/private/istrue.m
@@ -0,0 +1,42 @@
+function y = istrue(x)
+
+% ISTRUE ensures that a true/false input argument like "yes", "true"
+% or "on" is converted into a boolean
+
+% Copyright (C) 2009-2012, Robert Oostenveld
+%
+% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org
+% for the documentation and details.
+%
+%    FieldTrip is free software: you can redistribute it and/or modify
+%    it under the terms of the GNU General Public License as published by
+%    the Free Software Foundation, either version 3 of the License, or
+%    (at your option) any later version.
+%
+%    FieldTrip is distributed in the hope that it will be useful,
+%    but WITHOUT ANY WARRANTY; without even the implied warranty of
+%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+%    GNU General Public License for more details.
+%
+%    You should have received a copy of the GNU General Public License
+%    along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.
+%
+% $Id$
+
+true_list  = {'yes' 'true' 'on' 'y' };
+false_list = {'no' 'false' 'off' 'n' 'none'};
+
+if ischar(x)
+  % convert string to boolean value
+  if any(strcmpi(x, true_list))
+    y = true;
+  elseif any(strcmpi(x, false_list))
+    y = false;
+  else
+    ft_error('cannot determine whether "%s" should be interpreted as true or false', x);
+  end
+else
+  % convert numerical value to boolean
+  y = logical(x);
+end
+
diff --git a/statfun/private/istrue.m b/statfun/private/istrue.m
new file mode 100644
index 000000000..8148923f3
--- /dev/null
+++ b/statfun/private/istrue.m
@@ -0,0 +1,42 @@
+function y = istrue(x)
+
+% ISTRUE ensures that a true/false input argument like "yes", "true"
+% or "on" is converted into a boolean
+
+% Copyright (C) 2009-2012, Robert Oostenveld
+%
+% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org
+% for the documentation and details.
+%
+%    FieldTrip is free software: you can redistribute it and/or modify
+%    it under the terms of the GNU General Public License as published by
+%    the Free Software Foundation, either version 3 of the License, or
+%    (at your option) any later version.
+%
+%    FieldTrip is distributed in the hope that it will be useful,
+%    but WITHOUT ANY WARRANTY; without even the implied warranty of
+%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+%    GNU General Public License for more details.
+%
+%    You should have received a copy of the GNU General Public License
+%    along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.
+%
+% $Id$
+
+true_list  = {'yes' 'true' 'on' 'y' };
+false_list = {'no' 'false' 'off' 'n' 'none'};
+
+if ischar(x)
+  % convert string to boolean value
+  if any(strcmpi(x, true_list))
+    y = true;
+  elseif any(strcmpi(x, false_list))
+    y = false;
+  else
+    ft_error('cannot determine whether "%s" should be interpreted as true or false', x);
+  end
+else
+  % convert numerical value to boolean
+  y = logical(x);
+end
+