The designer uses a simulation device to gain first-hand insights into particular impairments or disabilities, for example clouded glasses to simulate sight loss or weighted gloves to reduce dexterity. The experience of using such a device can prompt an empathic understanding of users with disabilities or special conditions, and a greater appreciation of how inappropriate design can disable. Clients as well as designers can benefit from such tools. However this method complements but does not replace speaking to real people with disabilities. Also described as role playing.