The subject will receive a single conditioning stimulus (which should be ignored) followed by a pair of simultaneous vibrations which they will be asked to compare. Determine which of the simultaneous vibrations is larger / stronger / more intense and click on the corresponding box on the computer screen*.
This test is similar to the Amplitude Discrimination protocol, with the addition of a confounding pretest stimulus. Try to ignore the conditioning stimulus, but do not remove your finger from the tip. If you cannot detect a difference between the two stimuli, make the best guess possible.
*When hardware response is enabled, you may respond to each question by depressing the corresponding stimulus tip.