minimum difference in magnitude that a signal will be noticed.
The JND and magnitude of a signal are proportional. Keep in mind this is proportion, not a set difference. So if it is 50% then .5 of 100hz is 50hz difference, and .5 of 1000hz means a difference of 500hz.
Signal Detection Theory
effects of non-sensory factors (such as experiences, motives, and expectations) on perceptions of stimuli. For example, it may affect response bias ( hits, misses, false alarms, and correct negatives)
gathers and filters incoming light
muscular structure that controls the amount of light entering the pupil. It has a dilator and constrictor pupillae that do this.
refracts incoming light to focus it on the retina and is held in place by suspensory ligaments.
creates aqueous humor that drains into the canal of Schlemm