Pupillary dilation as an index of the orienting reflex.
D000161:Acoustic Stimulation; D006185:Habituation, Psychophysiologic; D006801:Humans; D009949:Orientation / Q000502:physiology*; D011680:Pupil / Q000502:physiology*; D012018:Reflex / Q000502:physiology*; D012025:Reflex, Pupillary