This is because the ability to decode pupil dilation is hardwired in our brains and subconsciously when looking into a pair of enlarged pupils in advertising (or in person), we think that we are looking at eyes that find us attractive.Īccording to some studies, the harder your brain works, (for example when you're calculating a tricky equation) the more your pupils will enlarge. For those who have darker coloured irises, this pupil size change would be less noticeable.įor this reason, often in advertising, the models' are photoshopped to have enlarged pupils, making the models look more attractive and alluring. When our gaze falls on a someone of interest to us, the brain releases a surge of dopamine, which triggers a pupil dilation. Studies have shown that pupil dilation correlates with arousal.

On the other hand, narcotics are known to cause 'pinpoint pupils'. Marijuana is a good example of this, as it triggers a release of dopamine, which excites the adrenergic receptors and induces mydriasis (dilation of the pupils).

Similarly, in order for the eye doctor to view the back of the eye during an eye exam, dilation eye drops work by relaxing the muscles in the iris that are responsible for constricting the pupils.įor example, 'Atropine' is a medication that enlarges the pupil and comes from a plant called Belladonna which is Italian for 'beautiful woman' (because historically the herb was used by women to make them appear more seductive).Ĭertain illegal drug can temporarily affect the ability of the iris to contract, which is why enlarged pupils can sometimes be an indication that someone has used illegal drugs.

This will pull on the lens, causing it to flatten and create a thinner contour allowing you to see distant objects in focus.Ī few medicines can affect the muscles that control your pupils preventing your pupils from getting smaller when the light shines in. Conversely, when you when you look at something further out into the distance, the diameter of your pupil will increase and muscles will relax in order to stretch the ligaments inside your eyes. When focusing your eyes on a near object your pupils will constrict to increase the depth of focus in the eye by blocking the light scattered by the periphery of the cornea. Conversely, in darker conditions, the pupil will enlarge as your eye will try to let in more light to see things you otherwise would have easily seen during the daytime. During the day less light is needed to see things around you, which is why the iris narrows and the pupil constricts and gets visibly smaller. Just as a camera requires the correct amount of light to capture vivid images - your eyes also need the correct amount of light to see properly.

However, there are a range of other emotional or physical environmental triggers which can cause your pupils to change in size which include. The pupil changes involuntarily, which is known as the pupil reflex. Nerve impulses travel down the optic nerve after light enters the eye, which affects the size of the pupil. This is controlled by muscles in the iris which will constrict or enlarge the pupil. The iris (the coloured part of the eye) plays an important role in the proper functioning of the eye, as it's primary job is to regulate how much (or how little) light enters the eye.

One pupil larger than other