Other Minds: The Octopus and the Evolution of Intelligent Life

by Peter Godfrey-Smith

Consider the case of tactile vision substitution systems (TVSS), a technology for the blind. A video camera is attached to a pad that sits on the blind person’s skin (for example, on their back). Optical images picked up by the camera are transformed into a form of energy (vibrations, or electrical stimulation) that can be felt on the skin. After some training with this device, the wearers start to report that the camera gives them an experience of objects located in space, not just a pattern of touches on their skin. If you are wearing such a system and a dog walks past, for example, the video system will make a moving pattern of presses or vibrations on your back, but under some circumstances this will not be experienced as vibrations on your back; instead you’ll experience an object moving out in front of you. This happens, though, only when the wearer is able to control the camera, to act and influence the incoming stream of stimulation. The user of the device has to be able to move the camera closer, change its angle, and so on. The simple way to do this is to attach the camera to the person’s body. Then the wearer can make objects loom, and come and go from the visual field. Subjective experience is intimately tied here to the interaction between behavior and sensory input. The moment-to-moment feedback between sensing and acting affects how sensory input itself feels.