The tongue display unit is a version of a tactile aid device that helps visually impaired individuals in conveying visual material by using the tongue. Tactile aid devices developed after the invention of the video camera, and the original development was made in the 1960s. It included a video camera that converted its images through an array of 400 small electrodes that were placed on the back of a user. The posts would vibrate depending on what was being shown on the screen, they would have a specific pattern of vibration for specific images. The subject would then guess what was being shown through the camera based off the vibrations on their back. To begin, the subjects were not able to decipher what the vibrations meant, they were just vibrations. With as little as a few hours, the subjects were able to analyze the patterns and create a mental image of what is being "shown" to them. It is not only able to work when the electrodes are on the subjects back, it is able to be moved around the exterior of their body and it would have no effect on their analyzation of the image. this goes to show that the brain portrays the skin as a sense organ that can distinguish patterns of touch.