Eye twitching is causes blepharospasm. There are many causes of eye twitching. The common ones are alcohol, caffeine, fatigue, lack of sleep, physical exertion, smoking, stress, and irritation to the eye or eyelid. Chronic causes include inflamed eyelids, dry eyes, light sensitivity, and pink eye.
Deception involves acting in such a way which leads another person to believe something, that you, yourself, do not believe to be true (see Ekman; Miller & Stiff). The following example helps illustrate this point: Brad and Spencer. Brad and Spencer are both part of the same circle of friends.
Others believe deception is necessary, because it allows participants to engage in a research study without behaving in an unnatural way; when conducting psychological research, it is important that participants behave the way they normally would if not being observed or studied.