MBS 93-24
Parallel Shift of Psychometric Function in Cutaneous and Color Discrimination
Tarow Indow
A model on latent processes is discussed as to judgments in the method
of constant stimuli when the following condition occurs. According to the
context, the psychometric function changes its location parameter but not
its slope. The interval of uncertainty for pressure stimuli applied to
the tips of left and right hand fingers increases as stated above when
their distances are increased by changing the position of the arms. Just-noticeable
differences in various directions from a color stimulus form an ellipsoid
in a color space and, when the mode of appearance is changed, its form
and orientation remain the same but its size is changed. In the respective
situation, the local stimulation in the sense organ is the same but, according
to the context, there is something different in perception. Correspondingly,
there must be some difference in excitations in the brain, which reflects
on the location parameter but not on the internal noise in the process.