Using this technique, it has been shown the pupil is smaller when a bright stimulus dominates awareness, relative to when a dark stimulus dominates awareness.[3][4] This shows that the pupillary light reflex is modulated by visual awareness. Similarly, it has been shown that the pupil constricts when you covertly (i.e., without looking at) pay attention to a bright stimulus, compared to a dark stimulus, even when visual input is identical.[5][6][7] Moreover, the magnitude of the pupil light reflex following a distracting probe is strongly correlated with the extent to which the probe captures visual attention and interferes with task performance.[8] This shows that the pupillary light reflex is modulated by visual attention and trial-by-trial variation in visual attention. Finally, a picture that is subjectively perceived as bright (e.g. a picture of the sun), elicits a stronger pupillary constriction than an image that is perceived as less bright (e.g. a picture of an indoor scene), even when the objective brightness of both images is equal.[9][10] This shows that the pupillary light reflex is modulated by subjective (as opposed to objective) brightness.