categorical perception/goodness of fit

[silvadmr <silvadmr@xxxxxxxxxx>]

Hi all! 

Could anybody help me?

In categorical perception research one generally looks for relations between categorization and discrimination tasks... 
As far as I know, the categorization task is always the same: the subject hears a sound and chooses one among two or more labels. Goodness of fit procedures are never employed (related studies in which goodness of fit tasks are employed are the studies on the "perceptual magnet effect").

Why not? Is there a reason? or is this just "praxis"?

As I understand it, goodness of fit results provide the same and more information! (at least if we have a reasonably small number of response categories, and assume that a criterion point reflected in the results of a simple classification task must be reflected in the results of  a "goodness of fit" task). 

For example, the subjects are presented with sounds drawn from a /u/-/o/ continuum. Is there any motive for using two rather than, say, four response categories(from "certainly 'u'" to "certainly 'o'")?
The predicted discrimination curve could be calculated considering only the critarion point separating "poor 'u'" and "poor 'o'".
I can not see disadvantages.

thaks in advance!