The method involves verifying the correct application of electrical stimuli through electrodes (11) placed in contact to the skin of the animal or human subject, where the electrical stimuli are pulses forming a signal whose frequency is greater than 10 Hertz. The increase in the intensity of the electrical stimuli is provided to detect the significant modification of the size or the shape of the pupil. The increase in the intensity of the electrical stimuli is stopped when the modification of the size or the shape of the pupil is detected. An independent claim is also included for a device for controlling the stimuli applied to the animal or human subject.
