/usr/share/psychtoolbox-3/PsychFiles/ is in psychtoolbox-3-common 3.0.9+svn2579.dfsg1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/psychtoolbox-3/PsychFiles/BreakLines.m
/usr/share/psychtoolbox-3/PsychFiles/CheckDirs.m
/usr/share/psychtoolbox-3/PsychFiles/Contents.m
/usr/share/psychtoolbox-3/PsychFiles/DirList.m
/usr/share/psychtoolbox-3/PsychFiles/FileFromFolder.m
/usr/share/psychtoolbox-3/PsychFiles/FindFolder.m
/usr/share/psychtoolbox-3/PsychFiles/FolderFromFolder.m
/usr/share/psychtoolbox-3/PsychFiles/LiteralUnderscore.m
/usr/share/psychtoolbox-3/PsychFiles/LogVar.m
/usr/share/psychtoolbox-3/PsychFiles/PsychHomeDir.m
/usr/share/psychtoolbox-3/PsychFiles/PsychSaveAsEps.m
/usr/share/psychtoolbox-3/PsychFiles/PsychtoolboxConfigDir.m
/usr/share/psychtoolbox-3/PsychFiles/QuoteString.m
/usr/share/psychtoolbox-3/PsychFiles/ReadStructsFromText.m
/usr/share/psychtoolbox-3/PsychFiles/ReplaceLineTerminators.m
/usr/share/psychtoolbox-3/PsychFiles/Var2Str.m
/usr/share/psychtoolbox-3/PsychFiles/WriteStructsToText.m