According to the LC-NE hypothesis, when a salient, or meaningful stimulus is presented, neurons in the locus coeruleus release norepinephrine, a neurotransmitter that benefits the detection of the stimulus. The effect of this release lasts for 100 ms after the salient stimulus is presented and benefits the second target when presented immediately after the first one, accounting for lag 1 sparing. Eventually the neurons in the locus coeruleus enter a refractory period, due to the auto-inhibitory effect of norepinephrine. According to the hypothesis, targets presented during this refractory period cannot trigger a release of norepinephrine, resulting in the attentional blink. The episodic distinctiveness hypothesis of the ST2 model suggests that the attentional blink reflects a limitation of the visual system attempting to allocate unique episodic contexts to the ephemeral target stimuli presented in RSVP.