A blink is a fast narrowing of the palpebral fissure, involving the activity of the orbicularis oculi muscle and, in those species with a nictitating membrane, of the retractor bulbi motor system and most extraocular eye muscles. Reflex blinks can be triggered by stimuli of different sensory modalities (trigeminal, visual, acoustic, and vestibular). Blinks are not exclusively related to corneal protection and wetting, but are also associated with some stages of visual processing and with the complex motor displays involved in the expression of emotional states. Lid movements also accompany eye displacements, as during vertical eye saccades and fixations. Moreover, eyelid movements can be easily evoked using classical conditioning procedures. 1‐9 Because of the technical facilities available for the quantitative evoking and recording of nictitating membrane and/or eyelid movements, 3 this motor system has become an excellent experimental model for the study of learned motor responses. In addition, available relevant information on this motor system can be used as a very useful tool for the understanding of the different pathologies related to facial kinematics and expression in humans.