[R] psychometric functions

[Mario Maiworm]

Hi,
I want to fit some psychophysical data with cumulative gaussians. There is
quite a convenient toolbox for matlab called 'psignifit' (formerly known as
'psychofit'). It allows the lower bound of the sigmoid to vary slightly from
zero, aswell as the upper bound to vary from one. with these two free
parameters, the fitted function is less sensitive to noisy data and
outliers.
Apart from advertising this toolbox I want to ask for possibilities in R to
fit psychometric functions, as I would rather use R than matlab. Is there a
comparable package specific for psychophysics in R? otherwise: which
function would be a good choice? Can I have functionality equal to
'psignifit' with glm() from MASS. I would be grateful for some suggestions
of people who have experience in sigmoid-fitting in R.
Best,
Mario.


__________________________________________________________________

Mario Maiworm
Biological Psychology and Neuropsychology
University of Hamburg
Von-Melle-Park 11
D-20146 Hamburg

Phone: +49 40 42838 8265
Fax: +49 40 42838 6591

http://bpn.uni-hamburg.de/Maiworm_e.html
http://cinacs.org