human-machine relationships can be characterised in a number of ways which relate to the function that the technology performs (Gray et al., 1995):

• Restorative Tools or machines that restore lost functions or limbs. Artificial hearts and prosthetic limbs are examples.
• Normalising Technologies that return existing limbs or organs to normality, such as hearing aids, spectacles, pacemakers or reconstructive surgery.
• Enhancing Technologies that improve human performance, such as night vision goggles, forklifts or communication technologies.
• Reconfiguring Technologies that create differences, but do not enhance human bodies, such as cosmetic breast implants, collagen injections, tattooing and body modification.

From: Miller, V. (2011) The Body and Information Technology. In: Understanding digital culture. London: Sage. pp. pp. 207–223.