The fact that one sample is preferred over the other does not mean
that it has a positive acceptance, i.e., an acceptance evidenced on the
positive region of the hedonic scale. However, in the method for measuring
the rejection threshold proposed by Prescott et al. (2005), preference
is compared between samples subjected to increasing intensities
of a stimulus (treatment) and a control sample. To correctly execute
the methodology, the control sample chosen by the researcher usually
exhibits a positive acceptance by the consumer. That minimises the
probability that a sample that did not statistically differ from the control
with regard to preference would have a negative acceptance or rejection.