The stimulus intensity that is detected half the time, on average, is called the threshold. difference adaptation weber absolute

the answer to the question is absolute threshold. In neuroscience and psychophysics an absolute threshold was defined as the lowest level of a stimulus i.e light, sound, touch e.t.c that an organism could detect. It can be influenced by several different factors such as the subjects motivations and expectations, cognitive processes and whether the subject is adapted to the stimulus.