Their structure is similar to that of the visual system of a human being, which could be said to consist of a pair of sensors (the eyes) mounted on a carrier (the body) and connected to a processor (the brain) that rapidly compares incoming images to others in memory to identify distinguishing features.
舉例來說，當眼睛（感測器）隨著身體（載體）移動，看到遠方有人走過來時，視覺會立即將影像傳至大腦記憶區（處理系統），經過快速比對後，就可以判斷來人是誰、高矮、美醜等。