/usr/share/psychtoolbox-3/Psychometric/FindEpsWeibTAFC.m is in psychtoolbox-3-common 3.0.11.20140816.dfsg1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | function epsilon = FindEpsWeibTAFC(pCorrect,beta)
% epsilon = FindEpsWeibTAFC(pCorrect,beta)
%
% Compute the epsilon corresponding to a particular
% percent correct. Mainly used with quest.
%
% Note that this is a less flexible version of the
% computation performed by QUEST('Epsilon'). This
% routine does not allow variations in gamma, delta
% or the psychometric function. It agrees with
% what QUEST('Epsilon') computes for gamma = 0.5,
% delta = 0, Weibull function.
%
% It would not be hard to fix this to include delta
% and gamma as parameters, but QUEST('Epsilon') seems
% to do the trick.
%
% 8/26/94 ccc, dhb Wrote it.
% 8/30/94 dhb Comment comparing to QUEST('Epsilon').
% Set gamma value for TAFC
gamma = 0.5;
if (pCorrect == 1)
pCorrect = 1-1e-15;
end
factor1 = - log( (1-pCorrect)/(1-gamma) );
epsilon = (1/beta)*log10(factor1);
|