Research in 2014 showed that people can sometimes dilate their pupils by imagining dark shapes or dark scenes. Think of those black bears assaulting a black campground at midnight, and your eyes may widen temporarily. Your pupils will get bigger as your eyes adjust to a further viewing distance. Another way to approach this is to suddenly unfocus your eyes, blurring your vision as much as you can. If you're doing this correctly, your eyes will feel very relaxed; if you start to see double, you've probably crossed your eyes and need to start over. With these techniques, you won't be able to observe your own eyes, so you'll need to record yourself or have a friend watch. As you probably know, pupils grow to let in more light. If you aren't able to dim the surrounding lighting, you can still dilate your pupils by turning to face away from windows and light source. Suck your stomach in and keep the muscles tight as you watch yourself in a mirror, to see whether your pupils increase. Some people can dilate their pupils in this way, although the underlying mechanism is unidentified. If you see no change after repeated tensing and bending, move on to a  different technique. Your pupils can dilate dramatically when you are excited, or especially when sexually stimulated, due to the release of oxytocin and adrenaline. In addition to dilated pupils, these chemicals also causes your mind to race, muscles to tense up, and breathing to go faster. Through biofeedback, people can learn to "drive" their adrenaline levels up or down.
تخيل غرفة مظلمة. ركز على الأجسام البعيدة أو ألغِ تركيز عينيك. انظر إلى جانب مظلم من الغرفة. جرب شد عضلات بطنك. تخيل شيئاً يحفز إفراز الأدرينالين.