Question: Neutral Stimulus (NS) Definition: A neutral stimulus is something that, at first, does not cause any automatic (reflex) response. It is just "there" and does not naturally trigger the behaviour. In the Video: At the beginning, the father's hand movement is a neutral stimulus. When he moves his hand, it does not automatically make his daughter blink. It has no special meaning yet and is not linked to the puff of air. It is only after he repeatedly pairs the hand movement with the air puff that the gesture starts to make her blink. Need Assignment Help?