Pupillary response Pupillary response Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve. A constriction response (miosis), is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates/opioids or anti hypertension medications. Constriction of the pupil occurs when the circular muscle, controlled by the parasympathetic nervous system (PSNS), contracts. A dilation response (mydriasis), is the widening of the pupil and may be caused by adrenaline, anticholinergic agents or drugs such as MDMA, cocaine, amphetamines and some hallucinogenics. Dilation of the pupil occurs when the
Sum of normally distributed random variables variables is normal, with its mean being the sum of the two means, and its variance being the sum of the two variances (i.e., the square of the standard deviation is the sum of the squares of the standard deviations). If one is to get the conclusion that the sum is normally distributed, the assumption that "X" and "Y" are independent cannot be dropped, although it can be weakened to the assumption that "X" and "Y" are jointly, rather than separately, normally distributed. (See here for an example.) The result about the mean holds in all cases, while the result