[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: identification task...negative d' values.
Negative values simply mean that the listener consistently used the
wrong label. Quite reasonable in an identification task, I
suppose. If the values are small (less than the variability of the
measure) I would chalk it up to random variability. If they are
large, then it is a meaningful result that should be interpreted. I
wonder, though, how are you calculating d' from three phoneme
labels? Feel free to contact me off-list.
Hearing Research Center
At 01:22 PM 5/2/2006, silvadmr wrote:
I have some few small negative values of d' obtained from an
identification task in witch subjects label vowel sounds from a
continuum with tree phoneme labels. Generally, the graphs and tables
in the literature never show negative values of d' ( i think
it occurs here and there).
The interpretation of such values from an identification task of
that kind must not be the same as the interpretation of negative
values obtained in a yes-no experiment...cause in the case of
indentification we have "different sounds" rather then a "signal
stimulus" and a "signal plus noise stimulus".
What is the usually adopted procedure?
Should I take the absolute values (given the nature of the
identification task)?...should I convert them to 0? should I keep
them as negative values?