Table 1.

Variables and methods for the UML object

Variables	Comments
uml.x	Signal intensity
uml.xnext	Next signal intensity, based on previous trials
uml.p	Current estimate of the posterior parameter distribution
uml.phi	Estimates of the psychometric- function parameters
uml.r	Subject’s binary responses in terms of correctness
uml.par	Data structure containing parameter space configuration
uml.n	Current trial number
uml.phi0	Parameters of the psychometric function for a virtual observer (used for simulation only)
uml.userdata01	Reserved for user-defined data
uml.userdata02	Reserved for user-defined data
uml.userdata03	Reserved for user-defined data
uml.userdata04	Reserved for user-defined data
Methods	Comments
Initialization:
uml = UML(par)	Construct a UML object
uml.setNdown(ndown)	Set the n-down, 1-up sweet-point selection rule
uml.setX0(x0)	Set the initial presentation level
Iteration:
uml.update(r)	Update the stimulus strength x, depending on response correctness r
Simulation:
uml.setPhi0(phi0)	Set the parameter uml.phi0
r = uml.simulateResponse(x)	Generate a response, and indicate correctness (r) from the virtual observer
Other:
conf = uml.getConf(percent)	Return the confidence limits of the parameters
uml.plotP()	Plot the posterior parameter distribution