Adjustment steps sized near the JND prevent subjects overestimating imperceptible changes

Evidence

The subject must be instructed to adjust the attribute value to one higher and lower than the reference before picking the final value. If possible, the adjustment is made in steps that are of the order of the JND to avoid the subject overestimating the change in the auditory event due to a minimal adjustment, the effect of which is actually not perceivable (Cardozo, 1965). — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 920