The way our body identifies the physical energy around us consists of two interdependent processes - sensation and perception. Sensation is the way our sense organs like eyes, nose, ears, skin, and tongue detect physical surroundings. Once detected, these organs send raw information to our brain where inputs are interpreted - this process is called perception.
Our visual system - the eye - consists of lens, cornea, iris, pupil, sclera, eye muscle, retina, optic nerve, and fovea. The most fascinating part of the eye, I believe, is the pupil. Our pupils, circular holes through which the light enters our eyes, have two purposes: visionary and psychological. Visionary significance of pupils is the reflex response to light - they decrease or increase amount of light allowed into our eyes (pupillary reflex).
The psychological significance of pupils, on the other hand, is absolutely fascinating: our pupils expand when we are trying to process complex information or when we are physically attracted to someone! Pupil dilation happens unconsciously and uncontrollably. According to Psychology Today, dilated pupils are an honest indicator of interest and attraction. Interestingly, when women and infants see babies, their pupils spontaneously dilate. This, however, does not apply to men. Furthermore, according to News Softpedia, recent research indicated that women, when they are in the fertile phase of their menstrual cycle, are more attracted to men with large pupils. Dilated pupils signaled women that men are interested in them this, in turn, made those men stand out as more noticeable partners because the attraction is mutual.